PP EGM-4 User manual

EGM-4 Environmental Gas
Monitor For CO2
Operator’s Manual
Version 1.00
© 2002 PP Systems. All Rights Reserved
29th October 2002
Europe North America
PP Systems PP Systems Inc.
Unit 2, Glovers Court, Bury Mead Road. 241 Winter Street
Hitchin, Hertfordshire, SG5 1RT, U.K. Haverhill, MA 01830 U.S.A.
Tel: [phone] Tel: [phone]
Fax: [phone] Fax: [phone]
Email: [e-mail]
Web Site: http://www.ppsystems.com

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Table of Contents
EGM-4 Operator's Manual – Version 1.00
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Table of Contents
Table of Contents...........................................................................................3
Preface............................................................................................................5
System Calibration........................................................................................5
User Registration ..........................................................................................5
Warning Notice...............................................................................................6
Condensation Risk........................................................................................6
PP Systems’ Contact Information..................................................................7
Technical Specification .................................................................................8
Introduction....................................................................................................9
Measurement Principle..................................................................................9
Getting Familiar With The EGM-4 ...............................................................10
Front Panel....................................................................................................................10
Top Of EGM-4...............................................................................................................10
Back Of EGM-4.............................................................................................................11
Environmental Sensor Inputs (I/O Ports).....................................................11
Analog Output.............................................................................................12
Current Output ............................................................................................12
RS232 Port..................................................................................................12
Soda Lime Absorber Column......................................................................12
Soda Lime.........................................................................................................................12
Keypad........................................................................................................12
LCD Display................................................................................................13
Gas Ports....................................................................................................13
Charge Socket ............................................................................................13
Power Supply/Charger......................................................................................................13
Power Switch ..............................................................................................13
Operation......................................................................................................14
Main Menu ..................................................................................................16
1REC...........................................................................................................16
Stand Alone CO2Analyser (Probe Type 0)......................................................................16
PP Systems Environmental Sensor Conversions: ...........................................................17
Environmental Monitor (Probe Types 1-6 and 10) ...........................................................18
PP Systems Environmental Sensor Conversions: ...........................................................19
Steady State Porometer (Probe Type 7)..........................................................................19
Closed System Soil Respiration (Probe Type 8)..............................................................20
Oxygen (Probe Type 9) ....................................................................................................23
Open System Soil Respiration (Probe Type 11) ..............................................................23
Calculation Of Fluxes For CFX And CPY Chambers .......................................................25
2SET...........................................................................................................25
1EGM................................................................................................................................25
2Z......................................................................................................................................26
Changing the Zero Type...................................................................................................26
Changing the Zero Time...................................................................................................26
3PMP................................................................................................................................26
4AV...................................................................................................................................27
5RECD..............................................................................................................................27
6ALM.................................................................................................................................27
Setting the Low CO2Alarm Setpoint ................................................................................28
Setting the High CO2Alarm Setpoint................................................................................28

Table of Contents
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7VOUT..............................................................................................................................28
3CAL...........................................................................................................29
Connecting Calibration Gas To The EGM-4.....................................................................29
4DMP..........................................................................................................30
Screen Display..................................................................................................................30
Data Dump........................................................................................................................32
Record Structure...............................................................................................................32
Data Structure Based On Probe/Sensors.........................................................................33
Error Codes ......................................................................................................................34
EGM Serial Outputs For Use With WINDOWS Data Transfer Program......35
5CLR...........................................................................................................35
6CLK...........................................................................................................35
Diagnostics and Initialisation......................................................................37
Diagnostics..................................................................................................37
Initialisation .................................................................................................37
Maintenance .................................................................................................38
Soda Lime Absorber Column......................................................................38
Soda Lime.........................................................................................................................38
MATERIAL SAFETY DATA FOR SODA LIME.................................................................39
Servicing The EGM-4..................................................................................40
Fuse..................................................................................................................................40
Inside The EGM-4.........................................................................................................41
Infrared Source.................................................................................................................41
EPROM.............................................................................................................................41
ZERO Valve......................................................................................................................42
12V Lead Acid Battery......................................................................................................42
Battery Specification.........................................................................................................42
Removing The 12V Battery ..............................................................................................43
Air Sampling Pump...........................................................................................................43
Replacing The Air Sampling Pump...................................................................................44
Cleaning The Air Sampling Pump ....................................................................................44
In-Line Hydrophobic Filter.................................................................................................45

Preface
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Preface
It is extremely important that you take the time to review this operator’s manual prior to
installation and operation of the EGM-4 CO2Gas Analyser. Otherwise, damage may be
caused which is not covered under our normal warranty policy.
System Calibration
• This product is shipped as a factory calibrated system. System calibration is not
required upon receipt from our factory.
• Familiarization with the documentation and calibration procedures is required prior to
future recalibration. See section 3CAL of this manual.
• All calibration related questions may be directed directly to PP Systems at:
In North America
Telephone: [phone]
Fax: [phone]
In Europe
Telephone: [phone]
Fax: [phone]
Email: [e-mail]
User Registration
It is very important that ALL new customers register with us to ensure that our user’s list is
kept up to date. If you are a PP Systems’ user, please register yourself electronically on our
web site at http://www.ppsystems.com/Register.html
Only REGISTERED users will be allowed access to our protected “Users” section of our web
site. This section will contain important product information including hardware/software
updates, application notes, newsletters, etc.
Thank you in advance for your cooperation.
The warranty excludes all defects in equipment
caused by incorrect installation, operation or
maintenance, misuse, alteration, and/or
accident.

Warning Notice
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Warning Notice
This instrument must not be used in situations where its failure could result in injury or
death. For applications where failure of this instrument to function correctly would
lead to consequential damage, the Analyser must be checked for correct operation and
calibration at intervals appropriate to the criticality of the situation.
This manual is provided to help you install and operate the equipment. Every effort has been
made to ensure that the information contained in this manual is accurate and complete. PP
Systems does not accept any liability for losses or damages resulting from the use of this
information.
PP Systems' equipment warranty is limited to replacement of defective components, and does
not cover injury to persons or property or other consequential damage.
This manual, and the information contained in it, is copyright to PP Systems. No part of the
manual may be copied, stored, transmitted or reproduced in any way or by any means
including, but not limited to, photocopying, photography, magnetic or other mechanical or
electrical means, without the prior written consent of PP Systems.
The EGM-4 is covered under warranty for one complete year, parts and labour included.
This, of course, is provided that the equipment is properly installed, operated and maintained
in accordance with written instructions (i.e. Operator's Manual).
The warranty excludes all defects in equipment caused by incorrect installation,
operation or maintenance, misuse, alteration, and/or accident.
If for some reason, a fault is covered under warranty, it is the responsibility of the customer to
return the goods to PP Systems or an authorised agent for repair or replacement of the
defective part(s).
Condensation Risk
If condensation occurs in the analysis sample line, free water may enter the analyser causing
serious damage which will result in a very expensive repair. Therefore, it is critical that you
periodically inspect the pipeline to be sure that condensed water does not enter the analyser.
An external, in-line, hydrophobic filter is currently supplied with all EGM-4’s (starting in
October 2002) and is available to all existing EGM customers. It consists of a 3 micron PTFE
hydrophobic filter (Cat. No. STD086) fitted inside an in-line filter holder (Cat. No. STD101). If
there is any risk of water in the sample line, we strongly recommend fitting the external
hydrophobic filter supplied to the “Gas In” line on the EGM-4 (see below). In addition, the
filter must be checked regularly and replaced if dirty. Otherwise, blockage can occur. The
filter holder is sealed by an “O” ring that should be kept lightly greased with silicone.
External hydrophobic
filter fitted to the “Gas
In” line to protect the
analyser from water.

Warning Notice
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For maintenance instructions, see In-Line Hydrophobic Filter.
If condensation appears to be a problem, we suggest increasing the flow rate. If
condensation persists, it is then recommended that a PP Systems’ water vapour equilibrator
(Part No. CRS090) is used. This is constructed from a material that is very permeable to
water vapour but impervious to CO2. If this is placed in-line in the analysis pipe at the
sampling point, the water vapour concentration of the analysis air will be brought close to
ambient.
The problem may also be avoided by putting a suitable water drop out trap or drier in the
same position. Drierite (anhydrous Calcium Sulphate) is suitable. DO NOT use Silica Gel,
which also absorbs CO2.
Please note that any method used to remove excess water from the analysis
sample will render any humidity measurement incorrect.
If you have any questions whatsoever with regards to possible condensation risk,
contact PP Systems (See PP Systems’ Contact Information).
PP Systems’ Contact Information
Europe NorthAmerica
PP Systems, Ltd. PP Systems, Inc.
Unit 2, Glovers Court, Bury Mead Rd. 241 Winter Street
Hitchin, Herts., SG5 1RT U.K. Haverhill, MA 01830 U.S.A.
Tel: [phone] Tel: [phone]
Fax: [phone] Fax: [phone]
Email: [e-mail]
Web Site: http://www.ppsystems.com

Technical Specification
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Technical Specification
Analysis Method Non-dispersive infrared with microprocessor control and linearisation.
Measurement
Range
(CO2)
%RH/Temperature
Sensor (Optional)
0-1,000 ppm (µmol mol-1)
0-2,000 ppm (µmol mol-1)
0-5,000 ppm (µmol mol-1)
0-10,000 ppm (µmol mol-1)
0-20,000 ppm (µmol mol-1)
0-50,000 ppm (µmol mol-1)
0-100,000 ppm (µmol mol-1)
RH: 0-100% RH
Accuracy: 2%
Temp: 0-45 °C
Accuracy: 0.5 °C
Measurements are automatically corrected for temperature and pressure.
Accuracy (CO2) 1% (limited by calibration gas mixture).
Linearity 1% FSD.
Stability Periodic “Auto-Zero” resulting in automatic correction for sample cell
contamination, source aging, detector sensitivity variations and pre-
amplifier gain changes.
Sample Pump Integral DC Pump
Air Filter Filtered Sample Line (hydrophobic).
Calibration Default value preset in factory (Built-in Initialisation). Automatic
calibration via keypad if required.
Control
CO2Control High and Low Set points
Alarm Audio Alarm
Data Logging
Real Time Clock Accuracy > 1 minute per month at 25˚C, operating temperature 0-70˚C.
Automatic correction for month end and leap years.
Recording Manual (by keypress) or automatic at user selected intervals between 1
and 250 minutes.
Data Storage 512 K Battery backed RAM (1,250 records).
Data Input/Output
Sensor Interface Input available for external sensors (i.e. % RH, temperature, PAR, O2)
Analog Output 4-20 mA, 0-1 V, 0-2 V, 0-3 V, 0-4 V, 0-5 V (Linear)
Digital Output
(RS232) 9600 baud/8 data bits, 1 start bit/2stop bits/no parity
ASCII Format
General
Display High contrast 2 x 16 character LCD.
Power Supply 12 V, 2.0 Ah Rechargeable Lead Acid Battery. (Up to 6 hours continuous
operation)
Gas Connections Two gas ports (inlet and exhaust) for 1/8” (.125) ID tubing.
Housing High Impact, Aluminium Enclosure.
Dimensions 158 W mm x 210 D mm x 62 H mm
Weight 1.5 kg.

Introduction
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Introduction
The EGM-4 CO2Analyser is a portable operated unit that is powered by an internal 12 V, 2.0
Ah lead acid rechargeable battery providing up to 6 hours continuous use. For extended
operation in the field (> 6 hours), PP Systems can also provide an external power supply
cable that will allow you to connect up to an external 12 V battery. If interested, please
contact PP Systems (See PP Systems’ Contact Information).
The EGM-4 is a high precision instrument for use in CO2monitoring applications such as
greenhouses, environment control rooms, nurseries and laboratories. Long term stability and
accuracy is ensured as a result of our unique “Auto-Zero” technology. The EGM-4 also
features inputs for additional sensors for measurement of O2, %RH, temperature, PAR, etc.
Measurement Principle
The EGM-4 CO2is a non-dispersive, infrared gas Analyser that features an “Auto-Zero”
facility. Using infra-red gas analysis techniques, we can readily determine CO2(Carbon
Dioxide) concentrations to within a few ppm and instantaneous measurements are possible.
Gases with di-atomic molecules such as CO2strongly absorbs photons in the infra-red range.
For CO2 , one region of strong absorption is 4.26 microns. A source emitting strongly at this
wavelength is a light bulb. If this is positioned at one end of a tube and at the other end is
placed a sensor that is sensitive to photons at 4.26 microns, we have a simple infra-red gas
Analyser. As carbon dioxide is passed down the sample cell, it absorbs some of the infra-red
and the sensor reading decreases. The “Auto-Zero” feature, which occurs at regular
intervals, allows for fast warm-up, adaptation to changing ambient conditions and excellent
stability of the CO2signal. The action of auto-zeroing minimizes the effects on span (gas
sensitivity) of sample cell contamination, source aging, changes in detector sensitivity and
changes in pre-amplifier gain.
The entire optical bench assembly (i.e. sample cell) is filtered and should never require
replacement.
To ensure proper operation, the EGM-4 MUST always
be operated in a vertical, upright position.
There are two CO2measurement ranges in the EGM-4, 30,000 and 99,999 ppm. All
instruments are checked and calibrated at the concentration specified at time of order to
ensure that the readings are within 1% of that value. When an instrument is reset to its
default values (i.e. when the system is initialised, see Error! Reference source not found.),
it returns to this setting.
It is important to note that the information contained in this documentation normally
refers to the latest firmware (EPROM) which can change over time. We recommend
that all users keep in contact with us from time to time to ensure that they are running
the most up to date system firmware.

Getting Familiar With The EGM-4
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Getting Familiar With The EGM-4
Front Panel
Top Of EGM-4
LCD Displa
y
(2 x 16)
Character
Ke
yp
ad
Sensor I/O
Connectors
RS232
Connector
Gas In Port
Gas Out Port

Getting Familiar With The EGM-4
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Back Of EGM-4
Environmental Sensor Inputs (I/O Ports)
The EGM-4 has 2 environmental sensor inputs (I/O) to allow external sensors (i.e. soil
respiration chamber, % relative humidity, temperature, PAR, etc.) to be used simultaneously.
All sensor inputs lines require 0-1V input. Note, the sensor inputs are displayed in mV (i.e. 0-
1,000 mV) instead of Volts.
If one of our environmental sensors is used with the EGM-4, it must be plugged into the
instrument prior to turning it on. The EGM-4 automatically detects the sensor connected as a
result of code resistors which are fitted to the 15 pin D Connector. The code resistors for our
environmental sensors are as follows:
Probe Type PP Systems Sensor Code Resistor
0 No Sensor Connected. The EGM-4 is
being used as a stand alone IRGA. Not applicable. This is determined by keypad
selection.
1 STP-1 Soil Temperature Probe 100 KΩ
2 HTR-2 %RH/Temp/PAR Probe 56 KΩ
3 HTR-1 %RH/Temp/PAR Probe 36 KΩ
4 PAR-1 Sensor 27 KΩ
5 PAR-1 (LUX) 20 KΩ
6 SRM-1 15 KΩ
7 Steady State Porometer (PMR-4) Not applicable. This is
determined by keypad
selection.
8 SRC-1 Soil Respiration Chamber 9.1 KΩ
9 RH/T/O220 KΩ
10 RH and Temperature 5.6 KΩ
11 CFX-1 Open System Soil Respiration
Chamber or CPY-3 Canopy Chamber. 4.3 KΩ
Note. If the sensor is not connected to the EGM-4 when first turned on, it will not be
detected and the subsequent displays will not be available.
External Power/Charger
Connector Power
(
On/Off
)
Fuse
(1A)
Soda
Lime
Cap

Getting Familiar With The EGM-4
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Analog Output
The EGM-4 has a 0-5V analog output. The default output is set at 0-5V. However, this can
be changed by the user (if required) to any value in between (i.e. 0-2V, 0-3V, 0-4V). (See
7VOUT).
Current Output
If required, current output (4-20 mA) is available. Inside the EGM-4, there is a 2 pin
connector labelled CN7 on the PC075-1 circuit board. Consult with PP Systems for further
information. A modification to the enclosure is required to gain access to connector CN7.
RS232 Port
The EGM-4 has one RS232 connector used for transferring stored data to a PC or laptop
computer. To transfer stored data from the EGM-4 to an external PC, connect the data
transfer cable (supplied by PP Systems) between the RS232 connector on the EGM-4 and
the 9 pin serial connector on the PC. Data transfer software (supplied by PP Systems) steps
you through the data transfer process. See Data Dump for more information on data
transfer. If required, this can be made up by the user if required. See table below:
15 PIN D Socket on
EGM-4 15 Pin D Socket on PC
Pin 2 Pin 2
Pin 5 Pin 5
Soda Lime Absorber Column
The absorber column is labelled “Soda Lime” on the rear panel. It contains a CO2scrubbing
desiccant known as Soda Lime. When air passes through this column, it removes all of the
CO2from the air stream. The “Auto-Zero” facility built into the EGM-4 periodically switches
the flow of gas from the Analyser through this column to check the Analyser zero. This
routine ensures long term stability and accuracy of the CO2Analyser. It automatically
corrects for such things as sample cell contamination, source aging, detector sensitivity and
changes in electronics.
Soda Lime
Soda lime is used to remove CO2from air entering the EGM-4. It is supplied as self-
indicating granules (1-2.5mm) that turn from green to brown as it becomes exhausted. The
contents of the absorber column should be replaced when it is 2/3rds exhausted (brown).
Soda Lime cannot be regenerated and should be discarded when exhausted. For accurate
measurements and calibration, it is absolutely critical that the EGM-4 absorber column is not
exhausted. If the soda lime is becoming exhausted, it will cause the ZERO to be performed
on non-ZERO air causing an error in the calibration.
When exhausted, the Soda Lime Cap should be removed along with the foam filter pad (with
the EGM-4 facing upwards) and the contents discarded. When replacing the soda lime, we
recommend using a funnel to ensure that the desiccant fills the absorber column. Leave
approximately 1” from the end of the column to allow the foam pad and cap to be refitted.
! CAUTION !
WASH YOUR HANDS AFTER HANDLING SODA LIME
Keypad
The keypad consists of 12 keys. There are ten keys that are labelled 0-9. Also, there are a
few keys that have additional functions. The Y/R (Yes/Record) key is used to accept settings
and to record measurements. In addition, the Y/R key is pressed to advance from one
display to the next. The Nkey is normally used to return to the Main Menu from

Getting Familiar With The EGM-4
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Measurement Mode, reject settings or to step back through the menus. The 8/X key is used
to toggle from one display to another in Measurement Mode.
LCD Display
The EGM-4 features a 2x16 character, backlit LCD display.
Gas Ports
There are two gas ports located on the top of the EGM-4. Each port is designed for use with
1/8” (.125) ID tubing. One gas port is labelled “Gas In” and the other “Gas Out”. The
sampling line should be fitted to the “Gas In” port using 1/8” tubing. The “Gas Out” line should
be left open to atmosphere to allow the sample air to exhaust without restriction. Note, for
closed system soil respiration measurements using our SRC-1 chamber, one gas line is
connected to the “Gas In” port and the other to the “Gas Out” port.
Charge Socket
The charge socket is labelled “12V DC” on the rear panel of the EGM-4. The AC
Adapter/charger supplied by PP Systems plugs into this socket to charge the internal 12V 2.0
Ah lead acid battery.
Power Supply/Charger
All systems are supplied complete with an AC Adapter/Charger designed specifically for use
with the EGM-4 for charging the internal 12 V 2.0 Ah lead acid battery. This unit has the
following technical specification:
Input 100-240 V ~ 50-60 Hz
Output 15 V @ 2.7 A
Power Indicator Green LED
Dimensions 10.5 cm x 6.5 cm x 4.5 cm
Weight 0.3 kg
!!! WARNING !!!
USE OF POWER SUPPLIES AND BATTERY CHARGERS OTHER THAN
THOSE SUPPLIED BY PP SYSTEMS FOR THE EGM-4 WILL INVALIDATE
THE WARRANTY.
Power Switch
To power up the EGM-4, the On/Off Switch should be toggled to the “On” position. To turn
the instrument off, the switch should be toggled to the “Off” position.

Operation
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Operation
The EGM-4 is a menu driven instrument. Note. If any external sensors/probes are to be
used with the EGM-4, they MUST be electrically connected to one (or both) of the I/O
ports prior to turning the instrument on. When the instrument is first powered up, it will go
through its normal warm-up period that takes approximately 5 minutes. Immediately after
powering up the system, the following is displayed:
Whereas:
EGML
Or
EGMH
Or
PMR
Refers to an EGM-4 with a measurement range of 30,000 ppm.
Refers to an EGM-4 with a measurement range of 99,999 ppm.
Refers to PMR-4 Steady State Poromter.
0456 Refers to the serial number of the EGM-4
V1.30 Refers to the firmware (EPROM).
During warm-up, there is a delay of approximately 45 seconds to allow for calibration of the
electronics and then the instrument proceeds to warm-up until the Analyser temperature
reaches 50 ˚C. A final Zero check is then performed before proceeding to the Main Menu.
Also during warm-up, several system checks are performed. The “Checksum” message is set
to a factory default value of 123456. If this is incorrect as when a new version of firmware is
first installed, a “CHECKSUM ERROR SEE MANUAL” message is displayed. If this occurs,
simply press any key to proceed to the Main Menu. From the Main Menu, press key 0 to re-
initialise the system (See Initialisation).
The next display will be dependent on whether or not any external sensors are being used
with the EGM-4.
If the EGM-4 is being used on its own, the following will be displayed:
Where:
C2000 Corresponds to the last calibration gas concentration. After DEFAULT, it is the
original range specified by the end user.
1V=2000 Range of the voltage signal corresponding to the CO2concentration.
R150 Number of records stored in memory.
If the EGM-4 is being used with an external sensor (i.e. SRC-1 Soil Respiration Chamber),
the following will be displayed:
PP SYSTEMS C2002
EGML 0456 V1.30
C2000 1V=2000
mV INPUTS R150
C2000 1V=2000
PROBETYPE 8 R150

Operation
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Where:
C2000 Corresponds to the last calibration gas concentration. After DEFAULT, it is
the original range specified by the end user.
1V=2000 Range of the voltage signal corresponding to the CO2concentration.
PROBETYPE 8 Refers to the probe/sensor connected to the EGM-4. For a list of probe
types, see Environmental Sensor Inputs (I/O Ports).
R150 Number of records stored in memory.
If the EGM-4 is being used as a porometer (i.e. PMR-4), the following will be displayed:
Where:
C2000 Corresponds to the last calibration gas concentration. After DEFAULT, it is
the original range specified by the end user.
1V=2000 Range of the voltage signal corresponding to the CO2concentration.
POROMETER Refers to the PMR-4.
R150 Number of records stored in memory.
After all system checks have been performed and the system achieves warm-up, the EGM-4
Main Menu is displayed as follows:
Note. If the instrument was just powered up, the display will show “WARM UP DELAY
TEMPERATURE = XX” until the instrument achieves its warm up temperature of 50 ˚C prior
to the Main Menu.
While in Measurement Mode, the following key presses can be performed:
Key To:
Z/0 Perform a manual Zero.
Y/R Record a measurement and place it in memory.
8/X Changes to a different display (See section 1REC).
N Return to the Main Menu.
Refer to the following sections for more information on menus and displays.
1REC 2SET 3CAL
4DMP 5CLR 6CLK
C2000 1V=2000
POROMETER R150

Operation
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Main Menu
There are 6 options available to the user when the Main Menu is displayed as follows:
Where:
Press
Key To
1 Go Into Measurement Mode. See 1REC
2 Change system settings (i.e. zero type and time interval, recording type, alarm
settings, etc.). See 2SET
3 To calibrate the Analyser. See 3CAL
4 To dump stored data to a PC or to view data on the LCD display. See 4DMP
5 Clear system memory. See 5CLR
6 Set/check the system clock (date and time). See 6CLK
Each option is discussed in further detail below.
1REC
To begin recording, press key 1. Please note, the EGM-4 display is dependent upon which
probe type is connected to it. The following table illustrates the Probe Types:
If the EGM-4 is used as a: Then The
Probe Type is
set to:
Stand Alone CO2Analyser. See Stand Alone CO2 Analyser
(Probe Type 0). 0
Environmental Monitor
(With one of our Environmental Sensors such as %RH,
temperature, PAR, O2, etc.). See Environmental Monitor
(Probe Types 1-6 and 10)
1-5
Steady State Porometer. See Steady State Porometer
(Probe Type 7) 7
Closed System Soil Respiration
(i.e. SRC-1 Soil Respiration Chamber). See Closed System
Soil Respiration (Probe Type 8)
8
RH/T and O2 probe 9
RH and Temperature 10
Open System Measurement
(i.e. CFX-1 Soil Respiration Chamber, CPY-3 Chamber). See
Open System Soil Respiration (Probe Type 11).
11
Important Note. Most instruments are supplied with the probe type already set if a sensor is
supplied with the EGM-4. If an existing EGM-4 user purchases an environmental sensor from
us, it may be necessary to set the probe type (see 1EGM).
Stand Alone CO2Analyser (Probe Type 0)
Immediately after pressing key 1, the instrument will automatically perform a zero check.
Once completed and assuming no problems with the zero, the instrument will proceed to
1REC 2SET 3CAL
4DMP 5CLR 6CLK

Operation
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“Measurement Mode” where the CO2value (plus Humidity if sensor is present), atmospheric
pressure and probe type are displayed as follows (Display 1):
Where:
C CO2 concentration (ppm)
H Humidity (mb). Only if a sensor is present.
A Atmospheric Pressure (mb)
P Probe Type
Press key 8/X to view record number, plot number, date and time (Display 2):
Where:
REC Record Number (up to 9999).
PLOT Plot Number (up to 99)
03-04 Date (3rd day of April)
12:40 Time (12:40 PM)
The record number resets each time the instrument starts or when the memory is cleared. It
counts up to 9999 and then resets automatically to 1. The internal EGM-4 memory allows
data storage of up to 1,000 records. Please note, when the memory is full, it overwrites
the oldest records.
Note. If the plot number needs to be changed, press key N when Display 2 above is shown
and enter the plot number desired. Next, press the Y key to continue. To return to Display 1
press key 8/X twice. Only the plot number can be changed at this point and the record
number automatically resets to 1 when the plot number changes.
Additional information may be viewed on the LCD display if required. Press key 8/X to view
signals (mV) from any external sensors that may be connected to the EGM-4 (Display 3):
Where:
A0244 Signal (mV) from sensor connected to Pin 1 on the 15 pin D connector. See
Environmental Sensor Inputs.
B0333 Signal (mV) from sensor connected to Pin 2 on the 15 pin D connector. See
Environmental Sensor Inputs.
0444 Signal (mV) from sensor connected to Pin 3 on the 15 pin D connector. See
Environmental Sensor Inputs. Due to the limits of the display, the letter C is not
displayed next to the signal.
D0555 Signal (mV) from sensor connected to Pin 4 on the 15 pin D connector. See
Environmental Sensor Inputs.
E0666 Signal (mV) from sensor connected to Pin 5 on the 15 pin D connector. See
Environmental Sensor Inputs.
PP Systems Environmental Sensor Conversions:
The following conversions need to be made to determine actual measurements of PAR, %RH
and temperature when using PP Systems’ environmental sensors.
PAR Sensor mV x 3 = PAR Level (µmol m-2 s-1)
%RH Sensor mV / 10 = %RH
Temperature mV / 20 = Temperature (˚C)
A0244 B0333 0444
D0555 E0666
C 365 H 13.5
A 0987 P 00
REC 0001 PLOT 00
03-04 12:40

Operation
EGM-4 Operator's Manual – Version 1.00
- 18 -
To return to the Main Menu while in Measurement Mode, simply press the N key.
Environmental Monitor (Probe Types 1-6 and 10)
Immediately after pressing key 1, the instrument will automatically perform a zero check.
Once completed and assuming no problems with the zero, the instrument will proceed to
“Measurement Mode” where the CO2value (plus Humidity if sensor is present) and sensor
values are displayed as follows (Display 1):
Where:
C CO2concentration (ppm)
H Humidity (mb). Only if a sensor is present.
T Air Temperature ( oC)
Q PAR (µmol m-2 s-1)
RH Relative Humidity (%RH)
Note. If the instrument was just powered up, the display will show “WARM UP DELAY
TEMPERATURE = XX” until the instrument achieves its warm up temperature of 50 ˚C prior
to entering into Measurement Mode.
Press key 8/X to view record number, plot number, date and time (Display 2):
Where:
REC Record Number (up to 9999).
PLOT Plot Number (up to 99)
03-04 Date (3rd day of April)
12:40 Time (12:40 PM)
The record number resets each time the instrument starts or when the memory is cleared. It
counts up to 9999 and then resets automatically to 1. The internal EGM-4 memory allows
data storage of up to 1,000 records. Please note, when the memory is full, it overwrites
the oldest records.
Note. If the plot number needs to be changed, press key N when Display 2 above is shown
and enter the plot number desired. Next, press the Y key to continue. To return to Display 1
press key 8/X twice. Only the plot number can be changed at this point and the record
number automatically resets to 1 when the plot number changes.
Additional information may be viewed on the LCD display if required. While in Measurement
Mode with the CO2concentration displayed, subsequent presses of the 8/X key will show 3
additional displays as follows:
Press key 8/X key again to view external sensor signals (in mV) as follows (Display 3):
Axxxx Bxxxx xxxx
Dxxxx Exxxx
C 365 H 13.5 T24.3
Q 1200 RH 65.3
REC 0001 PLOT 00
03-04 12:40

Operation
EGM-4 Operator's Manual – Version 1.00
- 19 -
Where:
A Signal (mV) from sensor connected to Pin 1 on the 15 pin
D connector. See Environmental Sensor Inputs.
B Signal (mV) from sensor connected to Pin 2 on the 15 pin
D connector. See Environmental Sensor Inputs.
xxxx Signal (mV) from sensor connected to Pin 3 on the 15 pin
D connector. See Environmental Sensor Inputs.
D Signal (mV) from sensor connected to Pin 4 on the 15 pin
D connector. See Environmental Sensor Inputs.
E Signal (mV) from sensor connected to Pin 5 on the 15 pin
D connector. See Environmental Sensor Inputs.
PP Systems Environmental Sensor Conversions:
The following conversions need to be made to determine actual measurements of PAR, %RH
and temperature when using PP Systems’ environmental sensors.
PAR Sensor mV x 3 = PAR Level (µmol m-2 s-1)
%RH Sensor mV / 10 = %RH
Temperature mV / 20 = Temperature (˚C)
To return to the Main Menu while in Measurement Mode, simply press the N key.
Steady State Porometer (Probe Type 7)
Immediately after pressing key 1, the instrument will display the following message to allow
the sensors to time for alignment (Display 1):
After approximately 3 seconds, the following is displayed to allow entry of record and plot
number if required (Display 2):
Where:
REC Record Number (up to 9999).
PLOT Plot Number (up to 99)
03-04 Date (3rd day of April)
12:40 Time (12:40 PM)
Note. If the plot number needs to be changed, press key N when Display 2 above is shown
and enter the plot number desired. Next, press the Y key to continue. To return to Display 1
press key 8/X twice. Only the plot number can be changed at this point and the record
number automatically resets to 1 when the plot number changes.
REC 0001 PLOT 00
03-04 12:40
KEY 2 = HUMIDITY
SENSOR BALANCE

Operation
EGM-4 Operator's Manual – Version 1.00
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To proceed to the Measurement Display, press the 8/X key (Display 3):
Where:
I Inlet Relative Humidity (%RH)
O Outlet Relative Humidity (%RH)
T Porometer Temperature (˚C)
Q PAR (µmol m-2 s-1)
F Flow Rate (ml/min)
G Stomatal Conductance (mmol (H2O) m-² s-¹)
The stomatal conductance calculation uses an exact determination of the energy balance.
To return to the Main Menu while in Measurement Mode, simply press the N key.
Closed System Soil Respiration (Probe Type 8)
Before starting any measurements with the SRC-1 Soil Respiration Chamber, see the section
on Condensation Risk at the beginning of this manual to ensure that you do not encounter
any problems related to water in the analyser.
Immediately after pressing key 1, the instrument will perform zero checks prior to displaying
the following message (Display 1):
The soil respiration rate is calculated by plotting the rate of change in the chamber CO2
concentration. The user has the option of saving the full data used in fitting the soil
respiration rate curve or the final results. If you want to save the full set of data, press key 1.
Note, data is collected every 4.8 seconds. If 1 is selected (ALL), the internal memory will
allow you to store approximately 80 minutes of continuous data. Since there is typically
several minutes in between measurements, you could expect to store approximately ½ a days
work. If 2 is selected, only the final results will be saved and recorded.
Next, choose linear or quadratic fitting for the soil respiration data (Display 2). If you are
unsure which option to choose, we recommend option 2QUAD (quadratic fitting). For more
information on this, please see the SRC-1 Soil Respiration Operator’s Manual.
Please note. If a quadratic fit is selected and the ppm change is less than 0.2ppm/second, a
linear fit is used.
The system always starts up with the SRC default values. Press key 1 to change the volume,
key 2 to change the area, etc. (Display 3):
I 22.3 O28.4 T22
Q1645 F245 G 0234
SOIL RESP.DATA
RECORD 1ALL 2END?
1V: 1171 2A: 78
3V/A*100 1491
DATA FITTING
1LINEAR 2 QUAD.?