biosystems PhD Lite User manual

Reference Manual
PhD Lite
Multi Gas Detector
651 South Main Street
Middletown, CT 06457 USA
[phone] [phone]
Fax [phone]
http://www.biosystems.com
Version 4.11 p/n 13-088
19APR2007

1

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THE PhD LITE PERSONAL PORTABLE GAS DETECTOR HAS BEEN DESIGNED FOR
THE DETECTION OF DEFICIENCIES OF OXYGEN, ACCUMULATIONS OF FLAMMABLE
GASES AND VAPORS AND ACCUMULATIONS OF TOXIC VAPORS.
IN ORDER TO ASSURE THAT THE USER IS PROPERLY WARNED OF
POTENTIALLY DANGEROUS ATMOSPHERIC CONDITIONS, IT IS
ESSENTIAL THAT THE INSTRUCTIONS IN THIS REFERENCE MANUAL
BE READ, FULLY UNDERSTOOD, AND FOLLOWED.
PhD Lite Reference Manual
Version 4.11
Copyright 2007
by
Biosystems
Middletown, Connecticut 06457
All rights reserved.
No page or part of this operation manual may be reproduced in any form
without written permission of the copyright owner shown above.
All rights reserved to correct typographical errors.

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Table of Contents
Chapter 1. Description ---------------------------------------------------------------------------------------7
1.1 PhD Lite capabilities------------------------------------------------------------------------------------------------------------7
1.2 Methods of sampling-----------------------------------------------------------------------------------------------------------7
1.3 Multi-sensor capability---------------------------------------------------------------------------------------------------------7
1.4 Calibration-------------------------------------------------------------------------------------------------------------------------7
1.5 Alarm logic-------------------------------------------------------------------------------------------------------------------------7
1.5.1 Alarm latch -------------------------------------------------------------------------------------------------------------------------------7
1.5.2 Atmospheric hazard alarms-----------------------------------------------------------------------------------------------------------8
1.5.3 Sensor overrange alarms.-------------------------------------------------------------------------------------------------------------8
1.5.4 Low battery alarms----------------------------------------------------------------------------------------------------------------------8
1.5.5 Other alarms and special microprocessor features ------------------------------------------------------------------------------9
1.6 Other electronic safeguards -------------------------------------------------------------------------------------------------9
1.6.1 Security beep ----------------------------------------------------------------------------------------------------------------------------9
1.7 Classification for intrinsic safety-------------------------------------------------------------------------------------------9
1.8 Sensors-----------------------------------------------------------------------------------------------------------------------------9
1.9 Continuous sample draw pump --------------------------------------------------------------------------------------------9
1.10 Black box data recorder----------------------------------------------------------------------------------------------------9
1.11 Remote Vibrating Alarm ----------------------------------------------------------------------------------------------------9
1.12 PhD Lite design components------------------------------------------------------------------------------------------- 10
1.13 PhD Lite standard accessories----------------------------------------------------------------------------------------- 10
1.13.1 Alkaline PhD Lite detectors ------------------------------------------------------------------------------------------------------ 10
1.13.2 NiMH PhD Lite detectors ---------------------------------------------------------------------------------------------------------10
1.14 PhD Lite kits------------------------------------------------------------------------------------------------------------------ 10
1.14.1 PhD Lite Confined Space Kits -------------------------------------------------------------------------------------------------- 10
1.14.2 PhD Lite Value Packs ------------------------------------------------------------------------------------------------------------- 10
Chapter 2. Basic operation--------------------------------------------------------------------------------11
2.1 Operational warnings and cautions ------------------------------------------------------------------------------------- 11
2.2 On and off sequences-------------------------------------------------------------------------------------------------------- 11
2.2.1 Start-up sequence -------------------------------------------------------------------------------------------------------------------- 11
2.2.1.1 Other start-up screens --------------------------------------------------------------------------------------------------------- 12
2.2.1.1.1 Non-standard alarms------------------------------------------------------------------------------------------------------- 12
2.2.1.1.2 “Warning Sensor Needs Cal”---------------------------------------------------------------------------------------------- 13
2.2.2 Shut-down sequence----------------------------------------------------------------------------------------------------------------- 13
2.3 Operating modes -------------------------------------------------------------------------------------------------------------- 13
2.3.1 Text Only mode------------------------------------------------------------------------------------------------------------------------ 13
2.3.2 Basic mode----------------------------------------------------------------------------------------------------------------------------- 14
2.3.3 Basic/Peak mode --------------------------------------------------------------------------------------------------------------------- 14
2.3.3.1 Peak readings-------------------------------------------------------------------------------------------------------------------- 14
2.3.3.2 To reset peak readings--------------------------------------------------------------------------------------------------------- 14
2.3.4 Technician mode---------------------------------------------------------------------------------------------------------------------- 14
2.3.4.1 STEL ------------------------------------------------------------------------------------------------------------------------------- 15
2.3.4.2 TWA readings--------------------------------------------------------------------------------------------------------------------15
2.3.4.3 Average readings----------------------------------------------------------------------------------------------------------------15
2.3.5 Changing operating modes --------------------------------------------------------------------------------------------------------- 15
2.4 Batteries-------------------------------------------------------------------------------------------------------------------------- 16
2.4.1 Alkaline batteries ---------------------------------------------------------------------------------------------------------------------- 16
2.4.1.1 Replacing alkaline batteries--------------------------------------------------------------------------------------------------- 16
2.4.2 NiMH rechargeable battery --------------------------------------------------------------------------------------------------------- 16
2.4.2.1 Storage guidelines for the NiMH battery.----------------------------------------------------------------------------------- 16
2.4.2.2 Charging guidelines for NiMH battery--------------------------------------------------------------------------------------- 16
2.4.2.3 Charging procedure for NiMH battery--------------------------------------------------------------------------------------- 16
2.4.3 Low battery alarms-------------------------------------------------------------------------------------------------------------------- 17
2.5 Methods of sampling--------------------------------------------------------------------------------------------------------- 17
2.5.1 Using the hand-aspirated sample draw kit--------------------------------------------------------------------------------------- 17
2.5.2. Motorized sample draw pump ------------------------------------------------------------------------------------------------------18
2.5.2.1 Using the continuous sample draw pump ---------------------------------------------------------------------------------- 18
2.5.2.2 Protective “low flow” shut-downs--------------------------------------------------------------------------------------------- 19

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2.5.2.3 Resuming diffusion monitoring ----------------------------------------------------------------------------------------------- 19
2.5.3 Sample probe assembly------------------------------------------------------------------------------------------------------------- 19
2.5.3.1 Changing sample probe filters------------------------------------------------------------------------------------------------ 20
2.5.3.2 Changing sample probe tubes------------------------------------------------------------------------------------------------ 20
2.6 Biosystems EEPROM equipped “Smart Sensors” ----------------------------------------------------------------- 20
2.6.1 Identification of type of sensor by instrument ----------------------------------------------------------------------------------- 20
2.6.2 Other information stored with the sensor EEPROM --------------------------------------------------------------------------- 20
2.6.3 Sensor removal and replacement ------------------------------------------------------------------------------------------------- 20
2.6.4 Missing sensor------------------------------------------------------------------------------------------------------------------------- 21
2.6.5 “Sensor not found” -------------------------------------------------------------------------------------------------------------------- 21
Chapter 3. Advanced Functions-------------------------------------------------------------------------22
3.1 The Main Menu ----------------------------------------------------------------------------------------------------------------- 22
3.1.1 Entering the Main Menu ------------------------------------------------------------------------------------------------------------- 22
3.2 The Alarm Menu---------------------------------------------------------------------------------------------------------------- 22
3.2.1 Entering the Alarm Menu ------------------------------------------------------------------------------------------------------------ 22
3.2.2 Custom alarm settings --------------------------------------------------------------------------------------------------------------- 22
3.2.3 Alarm and OK latches---------------------------------------------------------------------------------------------------------------- 23
3.2.3.1 Alarm latch settings ------------------------------------------------------------------------------------------------------------- 23
3.2.3.2 OK latch settings ---------------------------------------------------------------------------------------------------------------- 23
3.2.4 Default alarm settings ---------------------------------------------------------------------------------------------------------------- 24
3.2.4.1 Restore factory default alarm settings -------------------------------------------------------------------------------------- 24
3.2.5 Temperature alarm ------------------------------------------------------------------------------------------------------------------- 24
3.2.5.1 Enable/disable temperature alarms ----------------------------------------------------------------------------------------- 24
3.2.6 Warning alarms.----------------------------------------------------------------------------------------------------------------------- 25
3.2.6.1 Access warning alarm settings ----------------------------------------------------------------------------------------------- 25
3.2.6.2 Enable/disable warning alarms----------------------------------------------------------------------------------------------- 25
3.2.6.3 Adjust warning alarm levels --------------------------------------------------------------------------------------------------- 25
3.2.6.4 The warning alarm timeout function ----------------------------------------------------------------------------------------- 25
3.2.6.4.1 Adjust timeout interval ------------------------------------------------------------------------------------------------------ 25
3.2.6.4.2 Disabling the timeout interval---------------------------------------------------------------------------------------------- 26
3.3 The Calibration Menu -------------------------------------------------------------------------------------------------------- 26
3.4 The Options Menu------------------------------------------------------------------------------------------------------------- 26
3.4.1 Entering the Options Menu---------------------------------------------------------------------------------------------------------- 26
3.4.2 User Modes ---------------------------------------------------------------------------------------------------------------------------- 26
3.4.2.1 Overview of user modes ------------------------------------------------------------------------------------------------------- 26
3.4.2.2 Text Only Mode------------------------------------------------------------------------------------------------------------------26
3.4.2.3 Basic Mode ----------------------------------------------------------------------------------------------------------------------- 27
3.4.2.4 Basic/Peak Mode---------------------------------------------------------------------------------------------------------------- 27
3.4.2.4.1 Peak readings ---------------------------------------------------------------------------------------------------------------- 27
3.4.2.5 Technician Mode ---------------------------------------------------------------------------------------------------------------- 27
3.4.2.5.1 STEL--------------------------------------------------------------------------------------------------------------------------27
3.4.2.5.2 TWA readings ---------------------------------------------------------------------------------------------------------------- 27
3.4.2.5.3 Average readings ------------------------------------------------------------------------------------------------------------ 28
3.4.2.6 Changing the user mode------------------------------------------------------------------------------------------------------- 28
3.4.3 Security beep -------------------------------------------------------------------------------------------------------------------------- 28
3.4.3.1 Adjusting the security beep---------------------------------------------------------------------------------------------------- 28
3.4.4 Passcode ------------------------------------------------------------------------------------------------------------------------------- 29
3.4.4.1 Enable/Disable passcode------------------------------------------------------------------------------------------------------ 29
3.4.4.2 Changing the passcode-------------------------------------------------------------------------------------------------------- 29
3.4.4.3 Span Lock------------------------------------------------------------------------------------------------------------------------- 29
3.4.5 Language ------------------------------------------------------------------------------------------------------------------------------- 30
3.4.5.1 Changing the readout language---------------------------------------------------------------------------------------------- 30
3.4.6 DECIMAL: Changing the precision of the toxic sensor readout ------------------------------------------------------------- 30
3.4.7 Temperature units: Changing the temperature scale-------------------------------------------------------------------------- 30
3.5 The Screen Menu-------------------------------------------------------------------------------------------------------------- 31
3.5.1 Entering the Screen Menu ---------------------------------------------------------------------------------------------------------- 31
3.5.2 Adjusting the contrast ---------------------------------------------------------------------------------------------------------------- 31
3.5.3 Adjusting the backlight --------------------------------------------------------------------------------------------------------------- 31
3.5.3.1 Backlight ON Always ----------------------------------------------------------------------------------------------------------- 31
3.5.3.2 Adjusting the backlight interval ----------------------------------------------------------------------------------------------- 32
3.5.4 Adjusting the screen orientation---------------------------------------------------------------------------------------------------- 32

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3.5.4.1 Flip Display ----------------------------------------------------------------------------------------------------------------------- 32
3.5.4.2 Invert text color ------------------------------------------------------------------------------------------------------------------ 32
3.6 The View Menu ----------------------------------------------------------------------------------------------------------------- 32
3.6.1 Entering the View Menu ------------------------------------------------------------------------------------------------------------- 33
3.6.2 View alarm levels --------------------------------------------------------------------------------------------------------------------- 33
3.6.3 View battery voltage------------------------------------------------------------------------------------------------------------------ 33
3.6.4 View service information------------------------------------------------------------------------------------------------------------- 33
3.6.5 View Software Version--------------------------------------------------------------------------------------------------------------- 33
3.7 The Time Menu----------------------------------------------------------------------------------------------------------------- 33
3.7.1 Entering the Time Menu ------------------------------------------------------------------------------------------------------------- 33
3.7.2 Time and date settings--------------------------------------------------------------------------------------------------------------- 34
3.7.3 Service date settings ----------------------------------------------------------------------------------------------------------------- 34
3.7.3.1 Enable/Disable sensor service due dates---------------------------------------------------------------------------------- 34
3.7.3.2 Change sensor service due date settings---------------------------------------------------------------------------------- 34
Chapter 4. Calibration --------------------------------------------------------------------------------------36
4.1 Verification of accuracy ----------------------------------------------------------------------------------------------------- 36
4.2 Effect of contaminants on PhD Lite sensors------------------------------------------------------------------------- 36
4.2.1 Effects of contaminants on oxygen sensors------------------------------------------------------------------------------------- 36
4.2.2 Effects of contaminants on combustible sensors------------------------------------------------------------------------------- 36
4.2.3 Effects of high concentrations of combustible gas on the combustible sensor------------------------------------------- 37
4.2.4 Effects of contaminants on toxic gas sensors----------------------------------------------------------------------------------- 37
4.3 Single sensors capable of monitoring for two different gases------------------------------------------------- 37
4.3.1 Using one sensor to monitor for Carbon Monoxide and Hydrogen Sulfide------------------------------------------------ 38
4.3.1.1 Biosystems Duo-Tox dual purpose Carbon Monoxide/Hydrogen Sulfide sensor ---------------------------------- 38
4.3.1.2 Biosystems “CO Plus” dual purpose carbon monoxide/hydrogen sulfide sensor ---------------------------------- 38
4.3.1.2.1 Relative response of the CO Plus sensor to carbon monoxide and hydrogen sulfide------------------------- 38
4.3.2 Cl2and ClO2Non-Specific sensors------------------------------------------------------------------------------------------------ 38
4.3.2.1 Cl2 Non-Specific ----------------------------------------------------------------------------------------------------------------- 38
4.3.2.2 ClO2Non-Specific --------------------------------------------------------------------------------------------------------------- 38
4.4 Automatic calibration -------------------------------------------------------------------------------------------------------- 39
4.4.1 Automatic fresh air/zero calibration sequence ---------------------------------------------------------------------------------- 39
4.4.1.1 Reading “Too High” or “Too Low” for zero adjust------------------------------------------------------------------------- 39
4.4.2 Automatic span calibration sequence---------------------------------------------------------------------------------------------39
4.4.3 Automatic span calibration with more than one gas cylinder----------------------------------------------------------------- 40
4.5 Manual calibration------------------------------------------------------------------------------------------------------------- 41
4.5.1 Manual fresh air calibration procedure-------------------------------------------------------------------------------------------- 41
4.5.1.1 Shortcuts to the manual fresh air calibration procedures --------------------------------------------------------------- 41
4.5.1.1.1 Shortcut to fresh air calibration while in normal operation----------------------------------------------------------- 41
4.5.1.1.2 Shortcut to Main Menu while turning the PhD Lite on---------------------------------------------------------------- 42
4.5.2 Manual span calibration procedures ---------------------------------------------------------------------------------------------- 42
4.6 Functional (bump) test------------------------------------------------------------------------------------------------------- 42
4.7 The Calibration Menu -------------------------------------------------------------------------------------------------------- 43
4.7.1 Entering the Calibration Menu------------------------------------------------------------------------------------------------------ 43
4.7.2 Gas values ----------------------------------------------------------------------------------------------------------------------------- 43
4.7.2.1 Changing the combustible gas readout from LEL to CH4--------------------------------------------------------------- 43
4.7.2.2 Changing the direct reading setting of the CO Plus sensor from CO to H2S---------------------------------------- 44
4.7.3 Calibration reminder: ----------------------------------------------------------------------------------------------------------------- 45
4.7.3.1 Changing the calibration reminder ------------------------------------------------------------------------------------------- 45
4.7.3.2 Disabling the calibration reminder ------------------------------------------------------------------------------------------- 46
4.7.4 Calibration history--------------------------------------------------------------------------------------------------------------------- 46
4.7.5 Last calibration------------------------------------------------------------------------------------------------------------------------- 47
4.7.6 IQ Link----------------------------------------------------------------------------------------------------------------------------------- 47
Chapter 5. Record Keeping -------------------------------------------------------------------------------48
5.1 Overview of record keeping options------------------------------------------------------------------------------------ 48
5.2 Black box data recorder----------------------------------------------------------------------------------------------------- 48
5.3 Datalogger upgrade----------------------------------------------------------------------------------------------------------- 48
5.3.1 BioTrak database software---------------------------------------------------------------------------------------------------------- 48
5.3.2 IQ System ------------------------------------------------------------------------------------------------------------------------------ 49
5.4 Datalogger menu -------------------------------------------------------------------------------------------------------------- 49
5.4.1 Setting the datalogging interval ---------------------------------------------------------------------------------------------------- 49

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5.4.1.1 Enable/disable datalogger ---------------------------------------------------------------------------------------------------- 50
5.4.2 Clearing the datalogger -------------------------------------------------------------------------------------------------------------- 50
5.4.3 Sessions -------------------------------------------------------------------------------------------------------------------------------- 51
5.4.4 Communications mode -------------------------------------------------------------------------------------------------------------- 51
5.4.5 ID information -------------------------------------------------------------------------------------------------------------------------- 51
5.4.5.1 User and location lists---------------------------------------------------------------------------------------------------------- 51
5.4.5.2 User and location ID’s---------------------------------------------------------------------------------------------------------- 52
5.4.5.3 Touch ID option------------------------------------------------------------------------------------------------------------------ 53
5.4.5.3.1 Touch ID menu--------------------------------------------------------------------------------------------------------------- 53
5.4.5.3.1.1 Location memory ------------------------------------------------------------------------------------------------------- 53
5.4.5.3.1.2 User ID memory -------------------------------------------------------------------------------------------------------- 53
5.4.5.3.1.3 Clear ID button---------------------------------------------------------------------------------------------------------- 54
Chapter 6. Basic maintenance---------------------------------------------------------------------------55
6.1 Sensors--------------------------------------------------------------------------------------------------------------------------- 55
6.1.1 Sensor replacement ------------------------------------------------------------------------------------------------------------------ 55
6.1.2 New sensor releases ----------------------------------------------------------------------------------------------------------------- 56
6.1.3 Troubleshooting sensor problems ------------------------------------------------------------------------------------------------- 56
6.1.3.1 Can’t make automatic fresh air/zero calibration adjustment------------------------------------------------------------ 56
6.1.3.2 Can’t make span calibration adjustment.----------------------------------------------------------------------------------- 56
6.2 Motorized pump---------------------------------------------------------------------------------------------------------------- 56
6.2.1 Pump performance ------------------------------------------------------------------------------------------------------------------- 57
6.2.1.1 Verifying pump performance-------------------------------------------------------------------------------------------------- 57
6.2.1.2 Pump test failed ----------------------------------------------------------------------------------------------------------------- 57
6.2.1.3 Low flow pump failure ---------------------------------------------------------------------------------------------------------- 58
6.2.2 Internal pump filter replacement --------------------------------------------------------------------------------------------------- 58
6.2.3 Specific problems with motorized pump------------------------------------------------------------------------------------------ 58
6.2.3.1 Pump will not turn on ----------------------------------------------------------------------------------------------------------- 58
6.2.3.2 Can’t resume normal operation after a “Low Flow” shut down--------------------------------------------------------- 59
6.3 Sample probe assembly----------------------------------------------------------------------------------------------------- 59
6.3.1 Changing sample probe filters------------------------------------------------------------------------------------------------------ 59
6.3.2 Changing sample probe tubes ----------------------------------------------------------------------------------------------------- 59
6.4 Firmware upgrade from the Biosystems website------------------------------------------------------------------- 60
6.5. Returning your PhD Lite to Biosystems for service or repair------------------------------------------------ 60
6.6 Exploded view and parts list----------------------------------------------------------------------------------------------- 61
Appendices 62
Appendix A Toxic gas measurement - Ceilings, TWAs and STELs ------------------------------------------------ 62
1. Ceiling level: ------------------------------------------------------------------------------------------------------------------------------ 62
2. Time Weighted Average (TWA):------------------------------------------------------------------------------------------------------ 62
3. Short Term Exposure Limits (STEL): ------------------------------------------------------------------------------------------------ 62
Appendix B PhD Lite sensor ranges ----------------------------------------------------------------------------------------- 63
Appendix C Sensor Cross-Sensitivity Chart------------------------------------------------------------------------------- 64
Appendix D Calibration Frequency ------------------------------------------------------------------------------------------- 65
Appendix E Biosystems Standard Warranty Gas Detection Products-------------------------------------------- 66
Signal Words
The following signal words, as defined by ANSI Z535.4-1998, are used in the PhD Lite
Reference Manual.
indicates an imminently hazardous situation which, if not avoided,
will result in death or serious injury.
indicates a potentially hazardous situation which, if not avoided,
could result in death or serious injury.
indicates a potentially hazardous situation, which if not avoided, may
result in moderate or minor injury.
CAUTION used without the safety alert symbol indicates a potentially hazardous
situation which, if not avoided, may result in property damage.

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1. The PhD Lite personal, portable gas detector has been designed for the detection of
dangerous atmospheric conditions. An alarm condition indicates the presence of a potentially life-threatening
hazard and should be taken very seriously.
2. In the event of an alarm condition it is important to follow established procedures. The
safest course of action is to immediately leave the affected area, and to return only after further testing
determines that the area is once again safe for entry. Failure to immediately leave the area may result in serious
injury or death.
3. Use only Duracell MN1500 or Ultra MX1500, Eveready Energizer E91-LR6, Eveready EN91,
Radio Shack 23-874 (not ATEX approved) size AA 1.5V Alkaline batteries, Eveready CH15 (not ATEX approved) or
Radio Shack 23-149 (not ATEX approved) size AA 1.2V NiCad batteries, or Eveready L91 size AA 1.5V Lithium
batteries (not CSA or ATEX approved). Substitution of batteries may impair intrinsic safety.
4. The accuracy of the PhD Lite should be checked periodically with known concentration
calibration gas. Failure to check accuracy can lead to inaccurate and potentially dangerous readings. (The
Canadian Standards Association (CSA) requires an accuracy check using known concentration calibration gas
prior to each day’s use.)
5. The accuracy of the PhD Lite should be checked immediately following any known exposure
to contaminants by testing with known concentration test gas before further use. Failure to check accuracy can
lead to inaccurate and potentially dangerous readings.
6. A sensor that cannot be calibrated or is found to be out of tolerance should be replaced
immediately. An instrument that fails calibration may not be used until testing with known concentration test gas
determines that accuracy has been restored, and the instrument is once again fit for use.
7. Do not reset the calibration gas concentration unless you are using a calibration gas
concentration that differs from the one that is normally supplied by Biosystems for use in calibrating the PhD Lite.
Customers are strongly urged to use only Biosystems calibration materials when calibrating the PhD Lite. Use of
non-standard calibration gas and/or calibration kit components can lead to dangerously inaccurate readings and
may void the standard Biosystems warranty.
8. Use of non-standard calibration gas and/or calibration kit components when calibrating the
PhD Lite can lead to inaccurate and potentially dangerous readings and may void the standard Biosystems
warranty.
Biosystems offers calibration kits and long-lasting cylinders of test gas specifically developed for easy PhD Lite
calibration. Customers are strongly urged to use only Biosystems calibration materials when calibrating the PhD
Lite.
9. Substitution of components may impair intrinsic safety.
10. For safety reasons this equipment must be operated and serviced by qualified personnel
only. Read and understand this reference manual before operating or servicing the PhD Lite.
11. A rapid up-scale reading followed by a declining or erratic reading may indicate a hazardous
combustible gas concentration that exceeds the PhD Lite’s zero to 100 percent LEL detection range.
12. Use only the following Biosystems chargers to recharge the PhD Lite:
U.S. & Canada: 54-26-0201, 54-26-0202, 54-26-0204
Europe: 54-26-0205, 54-26-0206, 54-26-0207
U.K.: 54-26-0208, 54-26-0209
13. Use only the following pumps with the PhD Lite:
54-26-0101 (Standard), 54-26-0102 (Plated)

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Chapter 1. Description
1.1 PhD Lite capabilities
The PhD Lite gas detector can be configured to meet a
wide variety of requirements. This chapter provides an
overview of many of the features of the PhD Lite. More
detailed descriptions are contained in the subsequent
chapters of this manual.
1.2 Methods of sampling
The PhD Lite may be used in either diffusion or sample-
draw mode. In either mode, the gas sample must reach
the sensors for the instrument to register a gas reading.
The sensors are located inside of the instrument.
In diffusion mode, the atmosphere being measured
reaches the sensors by diffusing through vents in the
sensor compartment cover. Normal air movements are
enough to carry the sample to the sensors. The sensors
react quickly to changes in the concentrations of the gases
being measured. Diffusion-style operation monitors only
the atmosphere that immediately surrounds the detector.
The PhD Lite can also be used to sample remote locations
with either the hand-aspirated sample-draw kit that is
included with every PhD Lite, or with a motorized
continuous sample draw pump that is available separately.
During remote sampling, the gas sample is drawn into the
sensor compartment through the probe assembly and a
length of tubing.
Use of the sample draw kits is covered in section
2.5.1.
A detailed description of the PhD Lite probe assembly
is given in section 2.5.3.
1.3 Multi-sensor capability
The PhD Lite can be configured to simultaneously monitor
oxygen, combustible gases and vapors and either one or
two toxic gases. Sensors can be added, removed,
changed, and replaced in the field. The PhD Lite
microprocessor and “Smart Sensor” circuitry eliminates
the need for laborious reconfiguration procedures.
Note: It is necessary to verify the accuracy of the PhD
Lite by calibration with known concentration test gas
whenever a change is made to the sensors installed in
the instrument.
Calibration procedures are discussed in detail in
Chapter 4.
The PhD Lite uses electrochemical toxic gas sensors that
have been designed to minimize the effects of common
interfering gases. These sensors provide accurate,
dependable readings for toxic gases commonly
encountered during confined space entry and other
industrial applications. Toxic sensors currently available
for use in the PhD Lite include hydrogen sulfide (H2S),
carbon monoxide (CO), sulfur dioxide (SO2), phosphine
(PH3), ammonia (NH3), chlorine (Cl2), chlorine dioxide
(ClO2), hydrogen cyanide (HCN), nitric oxide (NO) and
nitrogen dioxide (NO2).
In addition to sensors designed to measure specific toxic
hazards, Biosystems also offers two different sensors
that allow for the simultaneous detection of both CO and
H2S.
The “Duo-Tox” sensor is a dual channel electrochemical
sensor designed to simultaneously detect both carbon
monoxide and hydrogen sulfide. The Duo-Tox allows
one sensor port to be used for the direct detection of both
carbon monoxide and hydrogen sulfide.
For more information on the Duo-Tox sensor see
section 4.3.1.1.
The “CO Plus” sensor is a single channel electrochemical
sensor. The CO Plus is ideal for situations requiring the
use of a single sensor to monitor for both Carbon
Monoxide and Hydrogen Sulfide, but where the user
does not need to know specifically which gas is present.
For more information on the CO Plus sensor see
section 4.3.1.2.
Different measurement units are used depending on the
gas being measured.
Type of Hazard Measurement unit
Oxygen (O2) Percentage by volume
Combustible gas Percentage of lower
explosive limit (%LEL)
All toxic sensors Parts per million (PPM)
Table 1.3. PhD Lite Standard Units of Measurement
Sensor configuration procedures are discussed in
greater detail in Chapter 2.
1.4 Calibration
The PhD Lite detector features fully automatic fresh air
and span calibration.
The accuracy of the PhD Lite
should be checked periodically with known
concentration calibration gas. Failure to check
accuracy can lead to inaccurate and potentially
dangerous readings. (The Canadian Standards
Association (CSA) requires an accuracy check using
known concentration calibration gas prior to each
day’s use.)
Calibration procedures are discussed in detail in
Chapter 4.
Use of these procedures is reserved for authorized
personnel.
1.5 Alarm logic
PhD Lite gas alarms are user-adjustable and may be set
anywhere within the range of the specific sensor type.
When an alarm set point is exceeded a loud audible
alarm sounds, and the bright red LED alarm light flashes.
The procedure for adjusting alarm settings is
covered in section 3.2.2.
1.5.1 Alarm latch
The PhD Lite includes a latching alarm feature that can
be enabled or disabled according to the needs of the
user. When the PhD Lite’s alarm latch is enabled, the

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audible and visible alarms will continue to sound even
after the atmospheric hazard has cleared. To turn the
alarm off, simply press the MODE button. If the PhD Lite’s
alarm latch is disabled and the alarm condition is no
longer present, the instrument will automatically return to
normal operation, and the visible and audible alarms will
cease without further input from the user.
The procedure for changing alarm and OK latch
settings is covered in section 3.2.3.
1.5.2 Atmospheric hazard alarms
The PhD Lite portable gas
detector has been designed for the detection of
deficiencies of oxygen, accumulations of flammable
gases and vapors, and accumulations of toxic vapors.
An alarm condition indicating the presence of one or
more of these potentially life-threatening hazards
should be taken very seriously.
In the event of an alarm condition
it is important to follow established procedures. The
safest course of action is to immediately leave the
affected area, and to return only after further testing
determines that the area is once again safe for entry.
Failure to immediately leave the area may result in
serious injury or death.
A rapid up-scale reading followed
by a declining or erratic reading may indicate a
hazardous combustible gas concentration that
exceeds the PhD Lite’s zero to 100 percent LEL
detection range.
The combustible gas alarm is activated when the percent
LEL (Lower Explosive Limit) gas concentration exceeds
the pre-set alarm point.
Two oxygen alarm set points have been provided; one for
low concentrations associated with oxygen deficiencies
and one for high concentrations associated with oxygen
enrichments.
Three alarm set points have been provided for each toxic
gas that is monitored: TWA (Time Weighted Average),
STEL (Short Term Exposure Limit), and Ceiling.
Appendix A discusses alarm levels and factory default
alarm settings.
The procedure for adjusting alarm settings is covered
in section 3.2.2.
1.5.3 Sensor overrange alarms.
The PhD Lite toxic gas channel will go into alarm if a
sensor is exposed to a concentration of gas that exceeds
its established range. If the peak alarm is enabled it will
go off before an overrange alarm provided a STEL or TWA
alarm is not activated first. If the peak alarm is disabled
and a toxic sensor goes into overrange alarm a “SENSOR
OUT OF RANGE” message will appear at the bottom of
the display while the audible and visible are activated.
The maximum range value will be displayed for the sensor
in alarm. If the LEL sensor goes into overrange alarm, the
message “LEL OVERRANGE” will intermittently appear,
both the audible alarm and the flashing LED alarms will be
activated and an “X” will appear on the LCD in the place
of the numeric reading for the LEL sensor.
In the event of an LEL overrange
alarm the PhD Lite must be turned off, brought to an
area that is known to be safe and then turned on
again to reset the alarm.
Note: The PhD Lite features automatic warning
against LEL sensor response failure due to lack of
oxygen. When oxygen levels fall below 10% of gross
volume, the PhD Lite will intermittently display a
message indicating that O2is too low for LEL to
operate.
1.5.4 Low battery alarms
Note: The voltage figures given below are for PhD
Lite instruments with firmware version 3.18 and may
be slightly different for units with other versions of
instrument firmware.
The PhD Lite includes low battery alarms that are
activated whenever battery voltage approaches a level
that will soon lead to instrument shut down. When the
battery voltage is reduced to approximately 3.23 volts, an
audible alarm will sound and the display will indicate that
a low battery condition exists. At this stage, the low
battery alarms may be silenced for a fifteen-minute
period by pressing the MODE button. After the first low
battery alarm, the alarm will sound again every fifteen
minutes until the voltage drops to the “Very Low Battery”
level.
The “Very Low Battery” level occurs when the battery
voltage drops to 3.13 volts. Due to the risk of imminent
shut down, when the battery voltage reaches the “Very
Low Battery” level it is no longer possible to silence the
low battery alarms. At this point, it is necessary to
immediately leave the hazardous area in which the
instrument is being used.
When the voltage drops to 3.10 volts, the PhD Lite will
display a "Dead Battery" message to warn the user of
imminent shut down. The instrument will then
automatically turn itself off.
After any low battery alarm the batteries should be
replaced if the PhD Lite is equipped with alkaline
batteries or the battery should be recharged if the PhD
Lite is equipped with a NiMH rechargeable battery.
The PhD Lite must be located in a
non-hazardous location whenever the alkaline
batteries are removed from the instrument.
Removing the alkaline batteries from the instrument
in a hazardous location may impair intrinsic safety.
Use only Duracell MN1500 or
Ultra MX1500, Eveready Energizer E91-LR6, Eveready
EN91, Radio Shack 23-874 (not ATEX approved) size
AA 1.5V Alkaline batteries, Eveready CH15 (not ATEX
approved) or Radio Shack 23-149 (not ATEX
approved) size AA 1.2V NiCad batteries, or Eveready
L91 size AA 1.5V Lithium batteries (not CSA or ATEX
approved). Substitution of batteries may impair
intrinsic safety.

9
1.5.5 Other alarms and special microprocessor
features
PhD Lite software includes a number of additional alarms
designed to ensure the proper operation of the instrument.
When the PhD Lite detects that an electronic fault or
failure condition has occurred, the proper audible and
visible alarms are activated and an explanatory message
is displayed.
The PhD Lite is designed to detect
potentially life threatening atmospheric conditions.
Any alarm condition should be taken seriously. The
safest course of action is to immediately leave the
affected area, and return only after further testing
determines that the area is once again safe for entry.
1.6 Other electronic safeguards
Several automatic programs prevent tampering and
misuse of the PhD Lite by unauthorized persons. Each
time the detector is turned on, the PhD Lite automatically
tests the LED alarm lights and audible alarm. The battery
is monitored continuously for proper voltage. The PhD
Lite also monitors the connection of sensors that are
currently installed. The detection of any electronic faults
causes the activation of the audible and visible alarms and
causes the display of the appropriate explanatory
message.
1.6.1 Security beep
The PhD Lite offers a security beep that may be
configured to “beep” at defined intervals to indicate that
the instrument is turned on.
Optional set-up choices, including security beep
settings, are accessed through the Options Menu.
See section 3.4.3 for details on the security beep.
1.7 Classification for intrinsic safety
The PhD Lite has the following certifications for intrinsic
safety:
UL Class I, Division 1, Groups A, B, C, and D
UL Class ll, Division 1, Groups E, F, and G
CSA Class I, Division 1, Groups A, B, C, and D
ATEX Certification:
II 2G EEx ia d IIC T4 (Alkaline) / EEx ia d IIC T3 (NiMH)
UL International DEMKO A/S 03 ATEX 130960X
The PhD Lite is also CE-Marked (Conformité
Européenne). The UL, CSA, and ATEX certification
marks indicate compliance with United States,
Canadian, and European Community requirements.
These classifications extend to instrument when
operated with the motorized pump.
1.8 Sensors
The PhD Lite can be configured to simultaneously monitor
Oxygen, combustible gases and vapors and either one or
two toxic gases. Up to three sensors can be installed in
the PhD Lite. With the “Duo Tox” dual channel CO/H2S
sensor installed, the instrument is capable of displaying
readings for up to four different channels of detection: O2,
LEL, CO, and H2S. The sensor configuration of the PhD
Lite can be specified at the time of purchase, or changed
in the field by appropriately trained personnel.
A sensor that cannot be
calibrated or is found to be out of tolerance must be
replaced immediately. An instrument that fails
calibration may not be used until testing with known
concentration test gas determines that accuracy has
been restored, and the instrument is once again fit
for use.
Calibration procedures are discussed in detail in
Chapter 4.
1.9 Continuous sample draw pump
An optional slip-on, motorized sample-draw pump is
available for situations requiring continuous "hands free"
remote monitoring.
The pump contains a pressure sensor that detects
restrictions in airflow caused by water or other fluids
being drawn into the unit and immediately acts to turn the
pump off in order to protect the sensors, pump, and other
PhD Lite components from damage.
Pump status is continuously monitored by the PhD Lite
microprocessor. A spinning “” icon located in the upper
left hand corner of the LCD display indicates that the
pump is attached and in normal operation. Low flow or
other pump fault conditions activate audible and visible
alarms and cause the display of the appropriate
explanatory message.
1.10 Black box data recorder
Starting with instrument firmware version 1.29, every
PhD Lite purchased without a datalogger has included a
“black box” data recorder that functions similarly to a
datalogger, with one important distinction. The data
stored in a PhD Lite with a datalogger option can be
accessed directly by the user with Biosystems’ Biotrak
Database Software. Instruments with the black box data
recorder must be sent back to Biosystems for data
retrieval.
If the data stored in a PhD Lite equipped with a black box
data recorder is needed, simply call Biosystems’
Instrument Service Department at [phone] for a
return authorization number and send the instrument
back to Biosystems. Biosystems will extract the data
from the instrument and print an incident report at no
charge. You only pay for shipping.
Datalogging functions are discussed in detail in
Chapter 5.
1.11 Remote Vibrating Alarm
The PhD Lite can be equipped with an optional remote
vibrating alarm for use in noisy environments. The MHP-
1 or MHP-2 remote alarm is designed to be worn on a
belt or shirt collar or placed inside a pocket, and is
connected to the instrument via a 20" or 40" cable.

10
During an alarm condition the MHP-1 will vibrate
continuously until the alarm condition is resolved.
Note: To use the MHP-1 or MHP-2 remote alarms, the
PhD Lite must be equipped with the remote alarm
connector.
1.12 PhD Lite design components
(1) Case: The instrument is enclosed in a solid, metal-
plated ABS case. A black PVC gasket between the
upper and lower sections of the case protects against
leakage or exposure to liquids.
(2) Front face: The front face of the instrument houses
the graphics capable LCD display, MODE button, four
navigation arrows, alarm light/IrDA port, and audible
alarm port.
(3) LCD display: A graphics capable liquid crystal
display (LCD) meter allows display of readings,
messages, menu and other information. An
automatically activated backlight allows the display to
be read even in low light conditions.
(4) Alarm light / IrDA port: Two bright red LED (light-
emitting diode) alarm lights provide a visual indication
of the alarm state. The lights are visible from the front
and top of the instrument. The light also functions as
the IrDA link to the unit for uploading to and
downloading from a PC.
(5) Control buttons: The large rectangular push-button
is called the MODE button. It is used to turn the PhD
Lite on and off, to confirm menu selections and to
access the automatic calibration sequences. The four
triangular navigation arrows are used to scroll or
navigate through additional menu choices and
screens of information.
(6) Sensor compartment cover: The sensors are
protected by a vented sensor compartment cover.
Each sensor is individually protected by its own
protective filter cap.
(7) Audible alarm: A cylindrical resonating chamber
extending past the sensor compartment contains the
loud audible alarm. Three small circular apertures in
the front face of the instrument cover the resonating
chamber.
(8) Battery compartment cover: For alkaline units, the
battery compartment cover provides access to the set
of three AA alkaline batteries. The cover is held in by
a knurled retention screw.
(9) Bottom surface: The belt clip attaches to the bottom
surface of the instrument.
1.13 PhD Lite standard accessories
Standard accessories included with every PhD Lite include
sample draw / calibration adapter, hand-aspirated sample-
draw kit, 2 feet of additional tubing for use during
calibration, reference manual, quick reference card and
training CD-ROM.
The sample draw kit consists of a sample draw /
calibration adapter, squeeze bulb, sample probe,
replacement sample probe filters, and ten feet of tubing.
Standard configurations of the PhD Lite are delivered in a
foam-lined box.
1.13.1 Alkaline PhD Lite detectors
If the PhD Lite has been purchased as an alkaline
instrument, the standard accessories also include a set of
3 disposable AA alkaline batteries.
For domestic orders, the batteries will be pre-installed in
the PhD Lite at the time of delivery (unless otherwise
requested).
For some international orders, the batteries may be
removed from the instrument prior to shipment.
1.13.2 NiMH PhD Lite detectors
If the PhD Lite has been purchased as a “NiMH”
instrument, the standard accessories also include a slip
in PhD Lite fast charger.
1.14 PhD Lite kits
PhD Lite detectors may also be purchased as part of a
complete kit that includes calibration gas, calibration gas
regulator and a hard-shell carrying case.
1.14.1 PhD Lite Confined Space Kits
In addition to the standard accessories listed above,
Confined Space Kits also include calibration fittings,
fixed-flow regulator with pressure gauge, and appropriate
large cylinder(s) of calibration gas in a foam-lined,
waterproof hard-shell carrying case.
1.14.2 PhD Lite Value Packs
PhD Lite Value Packs include an alkaline PhD Lite, all
standard accessories, calibration fittings, small
cylinder(s) of calibration gas, and fixed flow rate regulator
in a foam-lined non-waterproof hard-shell carrying case.
Figure 1.14.2 Major PhD Lite Features (Top and Front
Surfaces)

11
Chapter 2. Basic operation
This chapter will cover how to use the PhD Lite for safe
work in potentially hazardous atmospheres.
2.1 Operational warnings and cautions
1. The PhD Lite personal,
portable gas detector has been designed for the
detection of dangerous atmospheric conditions.
An alarm condition indicates the presence of a
potentially life-threatening hazard and should
be taken very seriously.
2. In the event of an alarm
condition it is important to follow established
procedures. The safest course of action is to
immediately leave the affected area, and to
return only after further testing determines that
the area is once again safe for entry. Failure to
immediately leave the area may result in serious
injury or death.
3. Use only Duracell MN1500
or Ultra MX1500, Eveready Energizer E91-LR6,
Eveready EN91, Radio Shack 23-874 (not ATEX
approved) size AA 1.5V Alkaline batteries,
Eveready CH15 (not ATEX approved) or Radio
Shack 23-149 (not ATEX approved) size AA 1.2V
NiCad batteries, or Eveready L91 size AA 1.5V
Lithium batteries (not CSA or ATEX approved).
Substitution of batteries may impair intrinsic
safety.
4. The accuracy of the PhD
Lite should be checked periodically with known
concentration calibration gas. Failure to check
accuracy can lead to inaccurate and potentially
dangerous readings. (The Canadian Standards
Association (CSA) requires an accuracy check
using known concentration calibration gas prior
to each day’s use.)
5. The accuracy of the PhD
Lite should be checked immediately following
any known exposure to contaminants by testing
with known concentration test gas before
further use. Failure to check accuracy can lead
to inaccurate and potentially dangerous
readings.
6. A sensor that cannot be
calibrated or is found to be out of tolerance
should be replaced immediately. An instrument
that fails calibration may not be used until
testing with known concentration test gas
determines that accuracy has been restored,
and the instrument is once again fit for use.
7. Do not reset the calibration
gas concentration unless you are using a
calibration gas concentration that differs from
the one that is normally supplied by Biosystems
for use in calibrating the PhD Lite.
Customers are strongly urged to use only
Biosystems calibration materials when
calibrating the PhD Lite. Use of non-standard
calibration gas and/or calibration kit components
can lead to dangerously inaccurate readings and
may void the standard Biosystems warranty.
8. Use of non-standard
calibration gas and/or calibration kit
components when calibrating the PhD Lite can
lead to inaccurate and potentially dangerous
readings and may void the standard
Biosystems warranty.
Biosystems offers calibration kits and long-
lasting cylinders of test gas specifically
developed for easy PhD Lite calibration.
Customers are strongly urged to use only
Biosystems calibration materials when
calibrating the PhD Lite.
9. Substitution of components
may impair intrinsic safety.
10. For safety reasons this
equipment must be operated and serviced by
qualified personnel only. Read and understand
this reference manual before operating or
servicing the PhD Lite.
11. A rapid up-scale reading
followed by a declining or erratic reading may
indicate a hazardous combustible gas
concentration that exceeds the PhD Lite’s zero
to 100 percent LEL detection range.
12. Use only the following
chargers to recharge the PhD Lite:
U.S. & Canada: 54-26-0201, 54-26-0202,
54-26-0204
Europe: 54-26-0205, 54-26-0206, 54-26-0207
U.K.: 54-26-0208, 54-26-0209
13. Use only the following
pumps with the PhD Lite:
54-26-0101 (Standard),
54-26-0102 (Plated)
2.2 On and off sequences
The rectangular push-button on the top of the PhD Lite
case is called the “MODE” button. It is used to turn the
PhD Lite on and off, to initiate the automatic calibration
sequence, and to confirm menu choices.
2.2.1 Start-up sequence
To turn the PhD Lite on:
1. Press the MODE button once and release it.

12
Several screens will be shown as the instrument loads
and evaluates information from the “Smart Sensors” that
are currently installed.
biosystems
OTP V.1.10
biosystems
PhD Lite V.3.18
Loading Sensors
O2
Loading Sensors
O2LEL
S/N 10470
Black Box DL
Date 19 Sept 2003
Time 14:25
The PhD Lite will then automatically go through an
electronic self-test and start-up sequence that will take
approximately thirty seconds.
Performing Self
Test
During the self-test sequence, the display backlight will
momentarily turn on, the visual LED alarm light will
flash, and the audible alarm will sound. The PhD Lite
will also determine which “Smart Sensors” are currently
installed in the instrument, and whether there have been
any changes since the last time the instrument was
used. The instrument will then proceed through the
time/date and battery/temperature screens.
Battery = 3.9V
Temp = 71F 22C
Note: The temperature shown is actually a reading
taken on the inside of the instrument case in the
area where the sensors are located and may not
correspond with ambient air temperatures. The PhD
Lite microprocessor uses these readings to
compensate for temperature changes in the sensor
compartment.
The instrument will proceed to display the current alarm
settings of the sensors it detects.
CURRENT ALARM
LEVELS
LOW ALARM LEVEL
O2= 19.5%
Other alarm level screens may be shown depending
upon the configuration of the instrument.
Note: PhD Lite alarm settings are adjustable by the
user and may be set anywhere within the detection
range of the specific sensor type. Factory default
settings may be easily restored at any time.
Sensor ranges for individual PhD Lite sensors are
given in Appendix C.
The procedure for changing alarm settings is
discussed in section 3.2.2.
Calibration Due
in 30 Days
After the self-test and start-up sequence is completed,
the current gas level screen will be shown. This screen
displays sensors currently installed and the current
readings. When the instrument is operated in “Basic”,
“Basic/Peak” or “Technician” mode, numerical readings
are shown.
O2LEL CO H2S
20.9 0 0 0
Current gas level screen in Basic, Basic/Peak and
Technician modes with no alarms present.
If the instrument is operated in the “Text Only” mode an
“OK” message will be displayed as long as measured
concentrations are below the alarm set points. If a
reading exceeds an alarm level, the message for the
affected sensor channel will change from “OK” to a
numerical reading, the LED alarm light will flash, and the
audible alarm will sound.
O2LEL CO H2S
OK OK OK OK
Current gas level screen in Text Only mode, no alarms
present.
2.2.1.1 Other start-up screens
Several additional screens may be shown under some
circumstances. Some screens may require the user to
acknowledge the message by pressing the MODE
button.
2.2.1.1.1 Non-standard alarms
"During the start up sequence, if the instrument detects
a low oxygen alarm setpoint of less than 18% or an LEL
ceiling alarm setpoint of greater than 30%, the LCD will
display a warning message indicating non-standard
alarms and will then display the non-standard alarm
setting(s) for the specific sensor(s)."
WARNING Alarms
Non-Standard
LEL Ceiling=50%
MODE=Acknowledge
Press the MODE button to acknowledge and use the
non-standard settings.
Note: Factory default settings may be easily
restored at any time. The procedure for restoring
factory default alarm settings is covered in section
3.2.4.1.

13
2.2.1.1.2 “Warning Sensor Needs Cal”
The PhD Lite will display the “Warning Sensor Needs
Cal” message for any of the following reasons:
1. The instrument’s sensor configuration has been
modified since the last time the instrument was
used.
2. The last calibration was not successfully completed.
3. The current date exceeds the calibration due date
that has been programmed into the instrument.
A sensor that cannot be
calibrated or is found to be out of tolerance should
be replaced immediately. An instrument that fails
calibration may not be used until testing with known
concentration test gas determines that accuracy
has been restored, and the instrument is once again
fit for use.
The “Needs Cal” warning message may be
acknowledged (and silenced) by pressing the MODE
button.
2.2.2 Shut-down sequence
To turn the PhD Lite off, hold the MODE button down
until the “Release Button” message appears. After the
MODE button is released the display will show the
message "Begin SHUTDOWN Please Wait”. The
shutdown sequence is complete when the display
blanks out.
Begin SHUTDOWN
Please Wait
Saving Instrument
Data
The PhD Lite will then shut itself off.
2.3 Operating modes
The PhD Lite offers a choice of four modes of operation:
"Text Only”, "Basic”, “Basic/Peak” and "Technician”.
Mode selection should be based on how much
information is required, the skill level of the user, and
the nature of the job.
Text Only Mode:
•Displays ‘OK’ for gas-level concentrations unless an alarm
condition is present.
•Upon alarm condition, actual gas-level concentrations will
be displayed.
•2 screens available (toggle by pressing the MODE button):
1. Current gas readings screen (see below).
2. Information screen (see below).
Basic Mode:
•Gas-level concentrations always displayed.
•Access to calibration functions.
•2 screens available (toggle by pressing the MODE button):
1. Current gas readings screen (see below).
2. Information screen (see below).
Basic/Peak Mode:
•Gas-level concentrations always displayed.
•Access to calibration functions.
•3 screens available (scroll by pressing the MODE
button):
1. Current gas readings screen (see below).
2. Peak readings screen (see below).
3. Information screen (see below).
Technician Mode:
•Gas-level concentrations always displayed.
•Access to calibration functions.
•4 screens available (scroll by pressing the MODE
button):
1. Current gas readings screen (see below).
2. Peak readings screen (see below).
3. STEL/TWA/AVG readings screen (see below).
4. Information screen (see below).
The INFORMATION screen (shown below) can be
accessed from any of the four operating modes by
pressing the MODE button.
01:15 15:08
3.9V 71F MENU
Regardless of mode selection, the PhD Lite remembers
the peak readings of all gases measured, and is
calculating the average readings, Time Weighted
Average (TWA) and Short Term Exposure Limit (STEL)
for any toxic gas sensors installed. Regardless of mode
selection the PhD Lite will go into alarm whenever any
alarm set point is exceeded.
2.3.1 Text Only mode
The simplest mode of operation is the "Text Only" mode.
In Text Only mode during normal operation, the LCD
screen indicates "OK” unless an alarm condition is
present.
O2LEL CO H2S
OK OK OK OK
Current gas level screen in Text Only mode, no alarms
present.
During an alarm condition the PhD Lite will no longer
display “OK” for the sensor that is in alarm. Instead, the
display will show the numerical gas reading value for the
sensor channel in flashing reverse text.
O2LEL CO H2S
19.1 OK OK OK
Current gas level screen in Text Only mode, oxygen alarm
PhD Lite alarms are self-resetting unless the alarm latch
is enabled. With the PhD Lite’s alarm latch enabled, the
audible and visible alarms will continue to sound after
the atmospheric hazard has cleared. To reset the
alarms, simply press the MODE button. If the PhD
Lite’s alarm latch is disabled and the alarm condition is
no longer present, the instrument automatically returns
to normal operation, and the visible and audible alarms
cease without further input from the user.

14
For more information on the alarm latch see section
3.2.3.1.
In Text Only mode, the information screen (see above)
is also available to the user. Press the MODE button to
toggle back and forth between the current gas level and
information screens.
Note: It is not possible to initiate the automatic
calibration sequence while the PhD Lite is in Text
Only mode. To initiate the “Auto-Calibration”
procedure, the PhD Lite must be in Basic,
Basic/Peak or Technician mode.
2.3.2 Basic mode
Basic mode is designed for users who require numerical
sensor readings at all times. In Basic mode numerical
gas level readings are always provided and it is possible
to initiate the automatic calibration sequence in order to
make fresh air and span calibration adjustments.
Calibration procedures are discussed in detail in
Chapter 4.
O2LEL CO H2S
20.9 0 0 0
Current gas level screen in Basic, Basic/Peak and
Technician Modes, no alarms present.
An alarm condition occurs when one of the sensor
readings exceeds the pre-set alarm level. When an
alarm condition occurs, the display will show the
numerical gas reading value for the sensor channel in
flashing reverse text, the LED alarm lights will flash, and
the audible alarm will sound.
O2LEL CO H2S
19.1 0 0 0
Current gas level screen in Basic, Basic/Peak and
Technician Modes, alarm condition.
PhD Lite alarms are self-resetting unless the alarm latch
is enabled. When the PhD Lite’s alarm latch is enabled,
the audible and visible alarm will continue to sound after
the atmospheric hazard has cleared. To reset the
alarms after the atmospheric hazard has cleared, simply
press the MODE button. If the PhD Lite’s alarm latch is
disabled and the alarm condition is no longer present,
the instrument automatically returns to normal
operation, and the visible and audible alarms cease
without further input from the user.
For more information on the alarm latch see section
3.2.3.1.
In Basic mode, the information screen is also available
to the user. While in Basic mode the MODE button may
be used to toggle back and forth between the current
gas level and information screens.
2.3.3 Basic/Peak mode
The Basic/Peak mode of operation provides users with
numerical sensor readings and access to the peak
readings screen. In Basic/Peak mode it is possible
initiate the automatic calibration sequence in order to
make fresh air and span calibration adjustments.
Calibration procedures are discussed in detail in
Chapter 4.
2.3.3.1 Peak readings
Peak readings for the accumulations of combustible
gases and vapors, and for the accumulation of toxic
gases represent the highest values registered by the
instrument during the period of operation. Peak
readings are updated at a rate of once per second.
Peak readings for oxygen include both the highest and
lowest values registered by the instrument during the
period of operation.
PEAK LOW HIGH
O2 20.7 20.9
Peak oxygen readings screen in Basic/Peak and
Technician modes.
PEAK LEL CO H2S
0 0 0
Peak LEL and toxic readings screen in Basic/Peak and
Technician modes.
While in Basic/Peak mode the MODE button may be
used to scroll through the current gas level, peak
readings, and information screens.
2.3.3.2 To reset peak readings
Peak readings may be reset during any period of
operation. To reset the peak readings:
1. Press the MODE button until the peak oxygen
reading screen appears.
PEAK LOW HIGH
O220.7 20.9
2. Hold the right navigation arrow down for
approximately one second or until the following
screen appears:
Reset Peaks?
YES NO
3. With YES highlighted, press the MODE button to
reset the peak settings
Note: If peak readings are reset, the PhD Lite’s data
recorder automatically records that the peak
readings have been reset and the word “PEAK” in
the peak readings screen will be highlighted for the
remainder of the current operating session.
PEAK LOW HIGH
O220.7 20.9
2.3.4 Technician mode
Technician mode provides access to all advanced
functions and displays of the PhD Lite.

15
While in Technician mode the MODE button may be
used to scroll through the current gas level, peak
readings, STEL, TWA, AVG and information screens.
2.3.4.1 STEL
The STEL (Short Term Exposure Limit) for a particular
toxic gas is the maximum average concentration to
which an unprotected worker may be exposed in any 15
minute interval during the day. The STEL value
displayed by the PhD Lite is the average concentration
for the most recently completed 15 minutes of operation.
Note: For the first 15 minutes after the PhD Lite is
initially turned on the STEL reading is a projected
value. The PhD Lite will begin projecting a STEL
value after the first 30 seconds of operation. For the
first 30 seconds the STEL screen will show an "X"
where the reading should be.
The STEL reading is continuously updated. Audible and
visible alarms will be activated immediately any time the
most recent 15-minute average exceeds the STEL
alarm set point.
STEL CO H2S
0 0
STEL screen in Technician Mode:
Appendix A discusses Permissible Exposure Limit
alarm calculations in greater detail.
2.3.4.2 TWA readings
Time Weighted Average or TWA values are calculated
by taking the sum of exposure to a particular toxic gas in
the current operating session in terms of parts-per-
million-hours and dividing by an eight-hour period.
TWA CO H2S
0 0
TWA screen in Technician Mode:
Note: It is not possible to calculate a toxic gas TWA
reading until the PhD Lite has been operating for 15
minutes. For the first 15 minutes after start-up, the
TWA screen will show an “X” in place of the
calculation. After 15 minutes, the TWA calculation
will be shown.
Appendix A discusses Permissible Exposure Limit
alarm calculations in greater detail.
2.3.4.3 Average readings
The average readings displayed by the PhD Lite are the
simple arithmetic averages registered by the instrument
during the current operating session.
AVERAGE O2LEL
20.9 0
Average readings screen for O2and LEL in Technician
Mode.
2.3.5 Changing operating modes
To change operating mode:
1. Press the MODE button until the information
screen is displayed.
01:15 15:08
3.9V 71F MENU
2. Hold down the left arrow key until EXIT appears and
is highlighted (approximately three seconds).
01:15 15:08
EXIT
3.9V 71F MENU
3. Press the down navigation arrow once to highlight
MENU and press the MODE button to enter the
Main Menu.
01:15 15:08
EXIT
3.9V 71F MENU
ALARMS CALIBRATION
OPTIONS SCREEN
VIEW TIME
EXIT
4. Use the navigation arrows to highlight OPTIONS
and press the MODE button to enter the Options
Menu.
ALARMS CALIBRATION
OPTIONS SCREEN
VIEW TIME
DISPLAY EXIT
USER_MODE SEC_BEEP
PASSCODE LANGUAGE
DECIMAL T_UNITS
EXIT
5. Once in the Options Menu, use the navigation
arrows to highlight USER MODE and press the
MODE button. The up and down navigation arrows
may then be used to toggle between operating
modes.
USER_MODE SEC_BEEP
PASSCODE LANGUAGE
DECIMAL T_UNITS
EXIT
Operating Mode
Text Only EXIT
↑↓
Operating Mode
Basic EXIT
↑↓
Operating Mode
Basic/Peak EXIT
↑↓
Operating Mode
Technician EXIT
6. Once the preferred operating mode is shown,
confirm the selection by pressing the MODE button.

16
Save Changes?
YES NO CANCEL
7. Press the MODE button with YES highlighted to
save the new operating mode.
Note: Changing the operating mode or otherwise
reprogramming the PhD Lite is reserved for
authorized employees.
2.4 Batteries
The PhD Lite can be equipped with either Alkaline of
NiMH rechargeable batteries
The PhD Lite must be located in
a non-hazardous location whenever the alkaline
batteries are removed from the instrument.
Removing the alkaline batteries from the instrument
in a hazardous location may impair intrinsic safety.
2.4.1 Alkaline batteries
The PhD Lite with alkaline batteries is designed to
provide up to 17 hours of continuous use with each set
of 3 fresh AA-cell disposable alkaline batteries.
Operation times may be reduced if the PhD Lite is used
with the motorized pump or in low light conditions where
the instrument backlight is on.
2.4.1.1 Replacing alkaline batteries
1. Check that the PhD Lite is not located in a
hazardous (potentially combustible) area.
2. Make sure that the PhD Lite is turned off.
3. Loosen the battery retention screw located at the
top of the instrument, remove the battery cap and
then remove the alkaline batteries.
4. Install new batteries in accordance with the diagram
underneath the battery cap and reinstall the battery
cap.
Note: Always dispose of alkaline batteries in
accordance with local ordinances.
Note: The PhD Lite is designed to turn itself on
whenever the batteries are removed and then
replaced. This ensures that in the event of a power
interruption, the instrument automatically turns
itself back on. Any time the batteries are
momentarily removed or replaced it will be
necessary to manually turn the PhD Lite off if the
instrument is not going to be put into immediate
use.
Use only Duracell MN1500 or
Ultra MX1500, Eveready Energizer E91-LR6,
Eveready EN91, Radio Shack 23-874 (not ATEX
approved)size AA, 1.5V Alkaline batteries, Eveready
CH15 (not ATEX approved) or Radio Shack 23-149
(not ATEX approved) size AA 1.2V NiCad batteries,
or Eveready L91 size AA 1.5V Lithium batteries (not
CSA or ATEX approved). Substitution of batteries
may impair intrinsic safety.
2.4.2 NiMH rechargeable battery
The PhD Lite may be equipped with a rechargeable
NiMH (nickel metal hydride) battery that is designed to
provide up to 17 hours of continuous use between
charging cycles. The NiMH battery pack is contained
inside of the PhD Lite and should only be replaced by
appropriately trained personnel.
Operation times may be reduced if either alkaline or
NiMH PhD Lites are used with the motorized pump or in
low light conditions where the instrument backlight is on.
2.4.2.1 Storage guidelines for the NiMH battery.
Never store NiMH-version PhD Lite instruments at
temperatures above 30 degrees Celsius (86 degrees
Fahrenheit). Nickel Metal Hydride batteries may suffer
deterioration resulting in damage to the internal
components when stored at high temperatures. The
battery may be irretrievably damaged resulting in
reduced battery capacity and voltage.
Biosystems recommends leaving PhD Lite instruments
with NiMH rechargeable batteries on the charger when
not in use.
2.4.2.2 Charging guidelines for NiMH battery
The NiMH battery in the PhD Lite should never be
charged at temperatures lower than 5 degrees Celsius
(40 degrees Fahrenheit) or higher than 30 degrees
Celsius (86 degrees Fahrenheit. Charging at
temperature extremes can cause permanent damage
the PhD Lite NiMH battery.
The PhD Lite must be located in
a non-hazardous location during the charging cycle.
Charging the PhD Lite in a hazardous location may
impair intrinsic safety.
Use only the following
Biosystems chargers to charge the PhD Lite:
U.S. & Canada: 54-26-0201, 54-26-0202, 54-26-0204.
Europe: 54-26-0205, 54-26-0206, 54-26-0207.
U.K.: 54-26-0208, 54-26-0209
2.4.2.3 Charging procedure for NiMH battery
1. Verify that the instrument is turned off. (If it is not,
press the MODE button for three seconds until the
message "Release Button" appears.)
2. Plug the power supply in and check to see that the
“POWER” indicator LED on the charging cradle is
lit.
3. Insert the PhD Lite into the charging cradle. While
the battery is charging the red ‘FAST’ indicator LED
will be lit on the charger.
Note: The “Charge” LED indicator will initially light
up and remain lit for the first 15 minutes regardless
of battery pack voltage.
4. Charging will be completed in 2 hours or less, and
will be indicated by the green ‘’TRICKLE’ indicator

17
LED. Charging is complete any time after the
“TRICKLE” indicator is lit.
CAUTION To achieve optimal charge and ensure
long battery life of the NIMH battery, make sure that
charging takes place in an area where the ambient
air temperature is between 40 and 86 degrees
Fahrenheit (5 and 30 degrees Celsius). Charging
the battery in temperatures above or below this
range can damage the battery and will drastically
affect battery life.
2.4.3 Low battery alarms
Note: The voltage figures given below are for PhD
Lite instruments with firmware version 3.18 and may
be slightly different for units with other versions of
instrument firmware.
The PhD Lite includes low battery alarms that are
activated whenever battery voltage approaches a level
that will soon lead to instrument shut down. When the
battery voltage is reduced to approximately 3.23 volts,
an audible alarm will sound and the display will indicate
that a low battery condition exists. At this stage, the low
battery alarms may be silenced for a fifteen-minute
period by pressing the MODE button. After the first low
battery alarm, the alarm will sound again every fifteen
minutes until the voltage drops to the “Very Low Battery”
level.
The “Very Low Battery” level occurs when the battery
voltage drops to 3.13 volts. Due to the risk of imminent
shut down, when the battery voltage reaches the “Very
Low Battery” level it is no longer possible to silence the
low battery alarms. At this point, it is necessary to
immediately leave the hazardous area in which the
instrument is being used.
When the voltage drops to 3.10 volts, the PhD Lite will
display a "Dead Battery" message to warn the user of
imminent shut down. The instrument will then
automatically turn itself off.
After any low battery alarm the batteries should be
replaced if the PhD Lite is equipped with alkaline
batteries or the battery should be recharged if the PhD
Lite is equipped with a NiMH rechargeable battery.
Use only Duracell MN1500 or
Ultra MX1500, Eveready Energizer E91-LR6,
Eveready EN91, Radio Shack 23-874 (not ATEX
approved)size AA, 1.5V Alkaline batteries, Eveready
CH15 (not ATEX approved) or Radio Shack 23-149
(not ATEX approved) size AA 1.2V NiCad batteries,
or Eveready L91 size AA 1.5V Lithium batteries (not
CSA or ATEX approved). Substitution of batteries
may impair intrinsic safety.
2.5 Methods of sampling
The PhD Lite may be used to sample the immediate
vicinity in diffusion mode, or it may be used to sample
remote locations. Sampling remote locations requires
the use of either the manual sample draw kit that is
included with the PhD Lite at purchase, or the PhD Lite
motorized sample pump that is available separately.
In normal operation, the PhD Lite functions as a
diffusion-style gas detector. The atmosphere reaches
the sensors by diffusing through the vents in the sensor
compartment cover. Normal air movements are enough
to carry the sample to the sensors. Once turned on, the
PhD Lite monitors continuously. The sensors react
quickly to changes in the concentrations of the gases
being measured. This type of "diffusion" operation
monitors only the atmosphere immediately surrounding
the detector.
To sample more remote locations. It is necessary to use
one of the two sample-draw kits that are available for
the PhD Lite. A manual sample draw kit comes as a
standard accessory with every PhD Lite and includes a
sample draw probe, squeeze bulb and ten feet of tubing.
A motorized sample draw pump is also available. In
either case the sample is drawn in through a sample
draw probe, and then proceeds through a length of hose
back to the sensor compartment.
2.5.1 Using the hand-aspirated sample draw kit
1. Connect the end of the hose that is closer to the
squeeze bulb to the sample draw adapter. Then
connect the other end of the hose to the sample
probe as shown in Figure 2.5.1.1.
2. Attach the sample draw adapter to the PhD Lite as
shown in Figure 2.5.1.2.
3. Cover the end of the sample draw probe assembly
with a finger, and squeeze the aspirator bulb. If
there are no leaks in the sample draw kit
components, the bulb should stay deflated for a few
seconds.
4. Insert the end of the sample probe into the location
to be sampled.
5. Squeeze the aspirator bulb several times to draw
the sample from the remote location to the sensor
compartment. Allow one squeeze of the bulb for
every one foot of sampling hose for the sample to
reach the sensors. Continue to squeeze the bulb
for an additional 45 seconds or until readings
stabilize.
6. Note the gas measurement readings.
Figure 2.5.1.1. Hand-aspirated sample draw kit

18
Figure 2.5.1.2. PhD Lite with hand-aspirated
sample draw kit attached
CAUTION: Hand aspirated remote sampling only
provides continuous gas readings for the area in
which the probe is located when the bulb is being
continuously squeezed.
Note: Each time a reading is desired, it is necessary
to squeeze the bulb a sufficient number of times to
bring a fresh sample to the sensor compartment.
2.5.2. Motorized sample draw pump
Use of the motorized sample draw pump allows the PhD
Lite to continuously monitor remote locations. The
pump is powered by the PhD Lite battery. When the
pump is attached and functioning normally, an animated
“” icon will appear in the upper left hand corner of the
LCD display.
O2LEL CO H2S
20.9 0 0 0
CAUTION: Never perform remote sampling with
the PhD Lite without the sample probe assembly.
The sample probe handle contains replaceable
filters designed to block moisture and remove
particulate contaminants. If the pump is operated
without the probe assembly in place, contaminants
may cause damage to the pump, sensors and
internal components of the PhD Lite.
The sample draw pump includes a pressure sensor
designed to protect the PhD Lite from exposure to water
or other liquids. If there is a change in pressure in the
sample draw assembly due to fluid intake or other
blockage, the pump immediately shuts down. After a
few seconds audible and visible alarms indicating a low
flow condition will also be activated.
CAUTION: Insertion of the sample draw tube
into a fluid horizontally or at a low angle may lead to
water ingress and may cause damage to the PhD
Lite.
The pressure sensor in the sample draw pump is
designed to detect pressure changes while the sample-
draw probe is being held in a vertical position. If the
probe is held horizontally or at a low angle while
inserted into a fluid, a pressure drop sufficient to cause
the pump to shut down may not be generated, and
water could be drawn into the pump assembly causing
damage to the pump, sensors and internal components
of the PhD Lite.
To avoid potential damage, care must be taken to keep
the probe vertical whenever fluids may be present.
Use only the following pumps
with the PhD Lite:
54-26-0101 (Standard), 54-26-0102 (Plated)
2.5.2.1 Using the continuous sample draw pump
1. Connect the pump to the hose and probe assembly
as shown below in Figure 2.5.2.1.
2. Slide the pump onto the PhD Lite as shown in
Figure 2.5.2.2.
3. Make sure the pump is securely attached. Tighten
the captive screw.
4. Turn on the PhD Lite. The pump will be activated
automatically when properly attached to the PhD
Lite. The display will indicate that the pump has
been detected.
Pump Detected
5. When prompted cover the end of the sample draw
probe assembly with a finger. If there are no leaks
in the sample draw components, a message will be
displayed indicating that the pump test passed.
Pump Testing
Block Sample
Pump Test Passed
Press Mode
6. Insert the end of the sample probe into the location
to be sampled.
7. Wait long enough for the pump to have drawn the
sample through the entire length of hose, and for
the sensors to have stabilized. (Allow one second
for each foot or three seconds for each meter of
sample hose for the sample to reach the sensors)
8. Note the gas measurement readings