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
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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