PP EGM-4 Operator's Manual

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Page 1

EGM-4 Environmental Gas

Monitor For CO

Operator’s Manual

Version 1.00

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: +44 1 462 453 411 Tel: +1 978 374-1064

Fax: +44 1 462 431 090 Fax: +1 978 374-0972

Email: [email protected]

Web Site: http://www.ppsystems.com

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Page 3

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 CO2 Analyser (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 T ype 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 CO2 Alarm Setpoint ................................................................................28

Setting the High CO2 Alarm Setpoint................................................................................28

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Table of Contents

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/Sensor s ......................................................................... 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

EGM-4 Operator's Manual – Version 1.00

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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 CO 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 docum entation and calibration procedures is r equired prior to future recalibration. See section

• All calibration related questions may be directed directly to PP Systems at:

In North America

Telephone: +1 978.374.1064

Fax: +1 978.374.0972

Telephone: +44 (0)1462.453411

Fax: +44 (0) 1462.431090

Email: [email protected]

Gas Analyser. Otherwise, damage may be

of this manual.

3CAL

In Europe

User Registration

It is very important that 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

site. This section will contain important product information including hardware/software updates, application notes, newsletters, etc.

users will be allowed access to our protected “U sers” section of our web

new customers register with us to ensure that our user’s list is

ALL

Thank you in advance for your cooperation.

The warrant y excludes all d efects in eq uipment

caused by incorrect installation, operation or

maintenance, misuse, alteration, and/or

accident.

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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 consequent ial damag e, the Analyser must be checked for correct operatio n and calibration at intervals appropriate to the criticality of the situation.

This manual is pr ovided to help you install and operate the equipment. Every effort has been made to ensure that the inf ormation 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' equipm ent warranty is lim ited to replac ement of defective components, and does not cover injury to persons or property or other consequential damage.

This manual, and the infor mation 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 c ourse, is provided that the equipm ent 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 som e 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 sam ple line, free water m ay enter the analyser causing serious damage which will result in a very expensive repair. Theref ore, 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 exis ting EGM cus tom ers. It consis ts of a 3 m icron PT FE hydrophobic filter (Cat. No. STD086) f itted 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. T he 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.

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Warning Notice

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 rec ommended 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 CO

. 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. which also absorbs CO

DO NOT

use Silica Gel,

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 North America

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: +44 1 462 453 411 Tel: +1 978 374-1064 Fax: +44 1 462 431 090 Fax: +1 978 374-0972

Email: [email protected]

Web Site: http://www.ppsystems.com

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Technical Specification

Analysis Method Measurement Range (CO

)

%RH/Temperature Sensor (Optional)

Accuracy (CO2) Linearity Stability

Sample Pump Air Filter Calibration

Control CO2 Control Alarm Data Logging Real Time Clock

Recording

Data Storage Data Input/Output Sensor Interface

Analog Output Digital Output (RS232) General Display Power Supply

Gas Connections Housing Dimensions Weight

Non-dispersive infrared with microprocessor control and linearisation. 0-1,000 ppm (µmol mol 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. 1% (limited by calibration gas mixture). 1% FSD. Periodic “Auto-Zero” resulting in automatic correction for sample cell contamination, source aging, detector sensitivity variations and preamplifier gain changes. Integral DC Pump Filtered Sample Line (hydrophobic). Default value preset in factory (Built-in Initialisation). Automatic calibration via keypad if required.

High and Low Set points Audio Alarm

Accuracy > 1 minute per month at 25 Automatic correction for month end and leap years. Manual (by keypress) or automatic at user selected intervals between 1 and 250 minutes. 512 K Battery backed RAM (1,250 records).

Input available for external sensors (i.e. % RH, temperature, PAR, O 4-20 mA, 0-1 V, 0-2 V, 0-3 V, 0-4 V, 0-5 V (Linear)

9600 baud/8 data bits, 1 start bit/2stop bits/no parity ASCII Format

High contrast 2 x 16 character LCD. 12 V, 2.0 Ah Rechargeable Lead Acid Battery. (Up to 6 hours continuous operation) Two gas ports (inlet and exhaust) for 1/8” (.125) ID tubing. High Impact, Aluminium Enclosure. 158 W mm x 210 D mm x 62 H mm

1.5 kg.

Technical Specification

-1)

C, operating temperature 0-70˚C.

)

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Introduction

The EGM-4 CO 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

The EGM-4 is a high precision instrument for use in CO greenhouses, environment contr ol room s, nur series 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 O

Measurement Principle

Analyser is a portable oper ated unit that is powered by an internal 12 V, 2.0

PP Systems’ Contact Information

monitoring applications such as

, %RH, temperature, PAR, etc.

The EGM-4 CO2 is a non-dispersive, infrared gas Analyser that features an “ facility. Using infra-red gas analysis techniques, we can readily determine CO

Auto-Zero”

(Carbon

Dioxide) concentrations to within a few ppm and instantaneous meas urements are possible. Gases with di-atomic molecules such as CO For CO

one region of strong absorption is 4.26 m icrons. A source emitting strongly at this

2 ,

strongly absorbs photons in the infra-red range.

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 m icrons, we have a simple infra-red gas Analyser. As carbon dioxide is passed down the sam ple 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 CO

signal. 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 CO 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 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.

measurement ranges in the EGM-4, 30,000 and 99,999 ppm. All

Error! Reference source not found.

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Getting Familiar With The EGM-4

LCD Displa (2 x 16) Character

Front Panel

Sensor I/O Connectors

RS232 Connector

Top Of EGM-4

Keypad

Gas In Port

Gas Out Port

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Getting Familiar With The EGM-4

Soda Lime

Cap

External Power/Charger

Connector

Power (On/Off)

Fuse (1A)

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 hum idity, temperature, PAR, etc.) to be used sim ultaneously. All sensor inputs lines require 0-1V input. Note, the s ensor inputs are dis played in mV (i.e. 01,000 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. T he EGM-4 autom atically detects the sensor c onnected as a result of code resistors which are fitted to the 15 pin D Connector. T he code res istors f or our environmental sensors are as follows:

Probe Type PP Systems Sens or Code Resistor

0 No Sensor Connected. The EGM-4 is

being used as a stand alone IRGA.

1 STP-1 Soil Temperature Probe 2 HTR-2 %RH/Temp/PAR Probe 3 HTR-1 %RH/Temp/PAR Probe 4 PAR-1 Sensor 5 PAR-1 (LUX) 6 SRM-1 7 Steady State Porometer (PMR-4) Not applicable. This is

8 SRC-1 Soil Respiration Chamber

9 RH/T/O2 10 RH and Temperature 11 CFX-1 Open System Soil Respiration

Chamber or CPY-3 Canopy Chamber.

If the sensor is not connected to the EGM-4 when first turned on, it will not be

Note.

detected and the subsequent displays will not be available.

Not applicable. This is

determined by keypad

selection.

100 KΩ

56 KΩ 36 KΩ 27 KΩ 20 KΩ 15 KΩ

determined by keypad

selection.

9.1 KΩ 20 KΩ

5.6 KΩ

4.3 KΩ

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Getting Familiar With The EGM-4

Analog Output

The EGM-4 has a 0-5V analog output. The default output is s et 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 sof tware (supplied by PP Systems) steps you through the data transfer process. See transfer. If required, this can be made up by the user if required. See table below:

15 PIN D Socket on

EGM-4

Pin 2 Pin 2 Pin 5 Pin 5

15 Pin D Socket on

Data Dump

for more information on data

Soda Lime Absorber Column

The absorber c olumn is labelled “Soda Lim e” on the rear panel. It contains a CO2 scrubbing desiccant known as Soda Lim e. When air pass es through this column, it rem oves all of the CO

from the air stream. The “Auto-Zero” fac ility built into the EGM-4 periodic ally 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 CO corrects for s uch things as sample cell contam ination, source aging, detector sensitivity and changes in electronics.

Analyser. It automatically

Soda Lime

Soda lime is used to remove CO2 from air entering the EGM-4. It is supplied as selfindicating granules (1-2.5m m) 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 exhaus ted, the Soda Lime Cap should be rem oved along with the foam filter pad (with the EGM-4 facing upwards) and the contents discarded. W hen 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 k eys. There are ten keys that are labelled few keys that have additional functions. The and to record measurements. In addition, the display to the next. The N key is normally used to return to the Main Menu from

EGM-4 Operator's Manual – Version 1.00

(Yes/Record) key is used to accept settings

Y/R

key is pressed to advance from one

Y/R

- 12 -

. Also, there are a

0-9

Page 13

Getting Familiar With The EGM-4

Measurement Mode, r eject settings or to step back through the menus. T he to toggle from one display to another in Measurement Mode.

key is used

8/X

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 EG M-4. Each port is designed f or 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 us ing 1/8” tubing. T he “ Gas O ut” line s hould be left open to atm osphere to allow the sample air to exhaust without restriction. Note, f or 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 sock et to charge the internal 12V 2.0 Ah lead acid battery.

Power Supply/Charger

All systems are supplied com plete 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 Output Power Indicator Dimensions Weight

100-240 V ~ 50-60 Hz 15 V @ 2.7 A Green LED

10.5 cm x 6.5 cm x 4.5 cm

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.

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Operation

The EGM-4 is a m enu driven instrum ent.

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.

through its normal warm-up period that takes approximately 5 minutes. Immediately after powering up the system, the following is displayed:

Whereas:

EGML

EGMH

PMR 0456 V1.30

During warm-up, there is a delay of approxim ately 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 inc orrect as when a new version of firm ware is first installed, a “CHECKSUM ERROR SEE MANUAL” m essage is displayed. If this occurs, simply press any key to proceed to the Main Menu. From the Main Menu, pr ess key 0 to reinitialise the system (See Initialisation).

The next display will be dependent on whether or not any external sensor s are being used with the EGM-4.

If the EGM-4 is being used on its own, the following will be displayed:

Where:

C2000

1V=2000 R150

If the EGM-4 is being used with an external sensor (i.e. SRC-1 Soil Respiration Chamber), the following will be displayed:

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. Refers to the serial number of the EGM-4 Refers to the firmware (EPROM).

Corresponds to the last calibration gas c oncentration. After DEFAULT, it is the original range specified by the end user. Range of the voltage signal corresponding to the CO Number of records stored in memory.

Note. If any external sensors/probes are to be

When the ins trum ent is f irst powered up, it will go

PP SYSTEMS C2002 EGML 0456 V1.30

C2000 1V=2000 mV INPUTS R150

concentration.

C2000 1V=2000 PROBETYPE 8 R150

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Operation

Where:

C2000

Corresponds to the last c alibration gas concentration. After DEFAULT, it is the original range specified by the end user.

1V=2000 PROBETYPE 8

Range of the voltage signal corresponding to the CO Refers to the probe/sensor connected to the EGM-4. For a list of probe

concentration.

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:

C2000 1V=2000 POROMETER R150

Where:

C2000

Corresponds to the last c alibration gas concentration. After DEFAULT, it is the original range specified by the end user.

1V=2000 POROMETER R150

Range of the voltage signal corresponding to the CO Refers to the PMR-4. Number of records stored in memory.

concentration.

After all system checks have been performed and the s ystem achieves warm-up, the EG M-4 Main Menu is displayed as follows:

1REC 2SET 3CAL 4DMP 5CLR 6CLK

If the instrument was just powered up, the display will show “WARM UP DELAY

Note.

TEMPERATURE = XX” until the ins trument 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

Z/0

Y/R

8/X

To: Perform a manual Zero. Record a measurement and place it in memory. Changes to a different display (See section

1REC

Return to the Main Menu.

Refer to the following sections for more information on menus and displays.

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Operation

Main Menu

There are 6 options available to the user when the Main Menu is displayed as follows:

Where:

Press

Key

1 2

3 4 5 6

Each option is discussed in further detail below.

Go Into Measurement Mode. See Change system settings (i.e. zero type and time interval, recording type, alarm settings, etc.). See To calibrate the Analyser. See To dump stored data to a PC or to view data on the LCD display. See Clear system memory. See Set/check the system clock (date and time). See

1REC 2SET 3CAL

1REC

2SET

3CAL

5CLR

4DMP

6CLK

1REC

To begin recording, press k ey 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 CO2 Analyser. See Stand Alone CO2 Analyser

(Probe Type 0).

Environmental Monitor (With one of our Environmental Sensors such as %RH, temperature, PAR, O

(Probe Types 1-6

Steady State Porometer. See

(Probe Type 7)

Closed System Soil Respiration (i.e. SRC-1 Soil Respiration Chamber). See

Soil Respiration (Probe Type 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).

Important Note.

supplied with the EGM-4. If an existing EGM-4 user purchas es an environmental sensor from us, it may be necessary to set the probe type (see

Most instruments are s upplied with the probe type already set if a sensor is

, etc.). See

and 10)

Environmental Monitor

Steady State Porometer

Closed System

1EGM

1-5

7 8

Stand Alone CO2 Analyser (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

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Operation

“Measurement Mode” where the CO pressure and probe type are displayed as follows (

value (plus Humidity if sensor is pres ent), atmospheric

Display 1

C 365 H 13.5 A 0987 P 00

Where:

C H A P

concentration (ppm)

Humidity (mb).

Only if a sensor is present.

Atmospheric Pressure (mb) Probe Type

Press key 8/X to view record number, plot number, date and time (

Display 2

REC 0001 PLOT 00 03-04 12:40

Where:

REC

PLOT

03-04 12:40

Record Number (up to 9999). Plot Number (up to 99) Date (3

day of April)

Time (12:40 PM)

The record num ber res ets each tim e the instr ument starts or when the memor y 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, pres s key N when Display 2 above is shown and enter the plot number desired. Next, pres s 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 m ay 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

A0244 B0333 0444 D0555 E0666

Where:

A0244

B0333

0444

Signal (mV) from sensor connected to

Environmental Sensor Inputs

Signal (mV) from sensor connected to

Environmental Sensor Inputs

Signal (mV) from sensor connected to

Environmental Sensor Inputs

. Due to the lim its of the dis play, the letter C is not

on the 15 pin D connector. See

Pin 1

on the 15 pin D connector. See

Pin 2

on the 15 pin D connector. See

Pin 3

displayed next to the signal.

D0555

E0666

Signal (mV) from sensor connected to

Environmental Sensor Inputs

Signal (mV) from sensor connected to

Environmental Sensor Inputs

on the 15 pin D connector. See

Pin 4

on the 15 pin D connector. See

Pin 5

PP Systems Environmental Sensor Conversions:

The following conversions need to be m ade to determ ine ac tual m easurem ents of PAR, %RH and temperature when using PP Systems’ environmental sensors.

PAR Sensor %RH Sensor Temperature

mV x 3 = PAR Level (µmol m

mV / 10 = %RH mV / 20 = Temperature (˚C)

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)

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Operation

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 CO values are displayed as follows (

Where:

C H T

concentration (ppm)

Humidity (mb). Air Temperature ( PAR (µmol m

-2 s-1

Relative Humidity (%RH)

If the instrument was just powered up, the display will show “WARM UP DELAY

Note.

TEMPERATURE = XX” until the ins trument 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 (

Where:

REC

PLOT

03-04 12:40

Record Number (up to 9999). Plot Number (up to 99) Date (3

day of April)

Time (12:40 PM)

the oldest records. Note.

Additional information m ay be viewed on the LCD display if required. While in Measurement Mode with the CO

concentration 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 (

value (plus Humidity if sensor is present) and sensor

Display 1

C 365 H 13.5 T24.3 Q 1200 RH 65.3

Only if a sensor is present.

)

Display 2

REC 0001 PLOT 00 03-04 12:40

Please note, when the memory is full, it overwrites

Display 3

Axxxx Bxxxx xxxx Dxxxx Exxxx

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Operation

Where:

xxxx

Signal (mV) from sensor connected to D connector. See

Environmental Sensor Inputs

Signal (mV) from sensor connected to D connector. See

Environmental Sensor Inputs

Signal (mV) from sensor connected to D connector. See

Environmental Sensor Inputs

Signal (mV) from sensor connected to D connector. See

Environmental Sensor Inputs

Signal (mV) from sensor connected to D connector. See

Environmental Sensor Inputs

on the 15 pin

Pin 1

on the 15 pin

Pin 2

on the 15 pin

Pin 3

on the 15 pin

Pin 4

on the 15 pin

Pin 5

. . . . .

PP Systems Environmental Sensor Conversions:

The following conversions need to be m ade to determ ine ac tual m easurem ents of PAR, %RH and temperature when using PP Systems’ environmental sensors.

PAR Sensor %RH Sensor Temperature

mV x 3 = PAR Level (µmol m

mV / 10 = %RH mV / 20 = Temperature (˚C)

To return to the Main Menu while in Measurement Mode, simply press the N key.

-2 s-1

)

Steady State Porometer (Probe Type 7)

Immediately after pr essing key 1, the instrument will display the following message to allow the sensors to time for alignment (

Display 1

KEY 2 = HUMIDITY SENSOR BALANCE

After approximately 3 seconds, the following is displayed to allow entry of record and plot number if required (

Display 2

REC 0001 PLOT 00 03-04 12:40

Where:

REC

PLOT

03-04 12:40

Record Number (up to 9999). Plot Number (up to 99) Date (3

day of April)

Time (12:40 PM)

Note.

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Operation

To proceed to the Measurement Display, press the 8/X key

(Display 3):

I 22.3 O28.4 T22 Q1645 F245 G 0234

Where:

Inlet Relative Humidity (%RH) Outlet Relative Humidity (%RH) Porometer Temperature (˚C) PAR (µmol m

-2 s-1

) Flow Rate (ml/min) Stomatal Conductance (

mmol (H2O) m

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 m easurem ents with the SRC-1 Soil Res piration Cham ber, see the section on Condensation Risk at the beginning of this m anual to ensure that you do not encounter any problems related to water in the analyser.

Immediately after pressing k ey 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 CO concentration. The user has the option of saving the full data used in fitting the soil respiration rate curve or the final res ults. If you want to save the full set of data, press k ey 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 meas urem ents, 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 ( unsure which option to c hoose, 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 volum e, key 2 to change the area, etc. (

SOIL RESP.DATA RECORD 1ALL 2END?

DATA F ITTING 1LINEAR 2 QUAD.?

Display 3

1V: 1171 2A: 78 3V/A*100 1491

Display 2

). If you are

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Operation

Where:

1V:

3V/A*100

Volume of the system up to 999,999 (ml) Area exposed up to 9999 (cm

) Volume/Area. This is automatically updated when there is a change to 1 (Volume) or 2 (Area). Also, if this value is changed directly, 1 (Volume) and 2 (Area) are set to maximum. The default value is 1491.

Press key Y to advance to the next dis play. Press key 1 to change the time, k ey 2 to change the CO

concentration or key 3 to change the approximate air temperature

(Display 4):

1DT:120 2DC:50 3 APPROX TEMP 25

Where:

1DT:

Time for which the change in the chamber CO

concentration is monitored

(seconds). The minimum and maximum values are 30 and 999 seconds respectively.

2DC:

The maximum change allowed in CO

concentration from time zero at which

point the final measurement is made (ppm)

3 APPROX

The approximate air temperature (°C)

TEMP

Press key Y to advance to the next display

(Display 5):

PLOT NO = 0 Y OR NEW VALUE

Where:

PLOT

Plot Number (up to 99)

Note.

If the plot number needs to be changed, s imply enter the new value and press key Y when Display 5 above is shown. T o return to Display 1 press key 8/X twice. Only the plot number can be changed at this point and the rec ord number automatically resets to 1 when the plot number changes.

The next display is as follows

(Display 6):

CHAMBER FLUSHING HOLD IN AIR 03

At this stage, the SRC-1 chamber should be held in the air to allow it to flush out prior to placing it on the soil. The number in the bottom right (03 in this case) is a count from 0-15 in

1.6 second increments. When completed, the following is displayed

(Display 7):

PLACE ON SOIL PRESS Y TO START

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Operation

After placing the SRC-1 cham ber on the soil, pres s the Y key. The following will be displayed

(Display 8)

EQUILIBRATION PLEASE WAIT 03

After approxim ately 5 seconds, the measurement will com mence. Before f inal calculation of soil respiration rate (g (CO data sets. The measurement display is as follows

) m2 Hour) can be achieved, the EGM-4 m ust have acc um ulated 4

(Display 9):

C00395 H14.7 T22 A02.11 Q0000 110

Where:

C00395

H14.7

T22

A02.11

Q0000

110

Current measured CO Humidity concentration

concentration (ppm)

if sensor is present

(mb)

Soil Temperature if probe is present (˚C)

exchange (Assimilation) rate (g (CO2) m2 Hour). The maxim um rate that

can be recorded is 99.99 g (CO PAR (µmol m

-2 s-1

)

) m2 Hour.

The elapsed time of measurement (seconds)

Please Note.

If the DC or DT exceeds the set values, the following message is displayed:

MEASUREMENT END RECORD Y/N

The following m essage will be shown with the quadratic fit if the C term in the quadr atic fitting expression (Y = a + bx + cx

) is greater than 0.1 x b.

NON LINEAR FIT

At this stage, the us er is given the opportunity to save the measurem ent even though the DC an DT settings were exceeded. If you still want to save the meas urement, press key Y. If not, press key N. After making your selection, the following is displayed:

REMOVE FROM SOIL THEN PRESS Y KEY

The measur ement process begins as des c ribed above.

If a ZERO is required, it will be

Note.

performed in between measurements. At any time, a key press of N will return you to the display that shows Volume, Area, etc. (Display 3 above) and the settings can be changed if required. A subsequent press of the N key will return you to the Main Menu.

To return to the Main Menu while in Measurement Mode, simply press the N key. For more information on the theory and calculation of soil respiration, please refer to the

SRC-1 Soil Respiration Chamber Operator’s Manual.

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Operation

Oxygen (Probe Type 9)

Where:

C H T

concentration (ppm)

Humidity (mb). Air Temperature ( O2 concentration (%) Relative Humidity (%RH)

and O2 value (plus Humidity and Temperature if sensor

Display 1

C 365 T24.3 O% 31.0 RH 65.3

Only if a sensor is present.

C).

Only if a sensor is present.

Open System Soil Respiration (Probe Type 11)

Before starting any m easurements with the CFX-1 or CPY-3 chambers , see the section on

Condensation Risk at the beginning of this m anual to ensure that you do not encounter any

problems related to water in the analyser. Immediately after pressing key 1, the instrument will display the following message

(

Display 1

Where:

Select the appropriate chamber (CPY-3 or CFX-1) . If one of the CPY-3 chambers is selected, it is necessary to enter or to check that the area c overed by the chamber is corr ect. Note, the entry is in cm smaller, the calculated flux will be the chamber flux.

After performing a Zero, the next display will be as follows (

1:5L

2:20L

3:100L

CFX

CPY 1:5L 2:20L 3:100L 4:CFX

Select 1 if operating our CPY-3 chamber with 5 Litre/min flow. Select 2 if operating our CPY-3 chamber with 20 Litre/min flow. Select 3 if operating our CPY-3 chamber with 100 Litre/min flow. Select 4 if operating our CFX-1 Soil Respiration Chamber

up to 9999 or approximately 1 m2. If 9999 is entered when the true area is

Display 2

REC 0001 PLOT 00 03-04 12:40

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Operation

Where:

REC

PLOT

03-04 12:40

Record Number (up to 9999). Plot Number (up to 99) Date (3

day of April)

Time (12:40 PM)

Note.

If the plot number needs to be changed, pres s key N when Display 2 above is shown and enter the plot number desired. Next, pres s 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.

To proceed to the first measurement display, press the 8/X key

(Display 3):

R00345 D+0020 T22 A06.15 F0300

Where:

R D T A F

Reference CO

concentration (ppm)

Difference between Reference and Analysis gas (ppm) Temperature of the CFX-1 or CPY-3 Chamber (˚C)

exchange (Assimilation rate) (µmol m2 s-1).

Flow Rate (ml/min)

If you press the 8/X k ey, the standard EGM-4 data is displayed (i.e. CO

, H2O, etc.). W ith the

CPY-3 chambers, the atmos pheric pressure Annnn is replac ed by the PAR reading (Qnnnn). If the EGM-4 is fitted with our optional humidity/temperature sensor, the H

O fluxes are

calculated and recorded but are not shown on the displays. The EGM-4 is an abs olute Analyser. When used with the CFX-1 Soil Respir ation Chamber,

an internal solenoid (built into the CFX-1) switches the gas stream from Reference and Analysis during 30 second intervals. As such, a m inimum of 45 seconds m ust elapse before valid data is available. At the conclusion of measurement, the following is displayed:

MEASUREMENT END RECORD Y/N

At this stage, the user is given the opportunity to save the measurem ent. If you want to save the measurem ent, pr es s key Y. If not, press key N. After making your selection, the following is displayed:

REMOVE FROM SOIL THEN PRESS Y KEY

The measur ement process begins as des c ribed above.

If a ZERO is required, it will be

Note.

To return to the Main Menu when any of the above displays are shown, simply press the N key.

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Operation

Calculation Of Fluxes For CFX And CPY Chambers

Both the CFX-1 and CPY-3 chambers us e Honeywell mass flowmeters that are calibrated at STP which is 0

for H

Convert the flow (V) measured in m l min of (A) cm

= ( V x 10000 ) / ( A x 22.414 x 1000 x 60) = (V / A ) x 7.436 x 10 With a CO ∆C x (V / A ) x 7.436 x 10 and with an H ∆H x (V / A ) x 7.436 x 10 For CO

For H

O, to convert to g H2O m2 h-1 , multiply by 64.87.

C and 1013mb. Results are given in µmol m

-1

to mol m-2 s

differential between the inlet and outlet of ∆C ppm, the CO2 flux is:

O differential between the inlet and outlet of ∆H mb, the H2O flux is:

to convert to g CO2 m2 h

-1

(Molar Volume at STP is 22.414 l.)

-1

, multiply by 0.1584.

at STP through the chamber with an exposed ar ea

-3

µmol m-2 s

-3

mmol m-2 s-1 .

-1

-2 s-1

for CO2 and in mmol m

-2 s-1

-3

2SET

Press key 2 from the Main Menu if you need to:

• Select/change probe types the EGM-4 (

• Select/change the EGM-4 Zero (2Z).

• Enable/disable sampling pump (

3PMP).

• Determines within which range of outputs the average is to be taken (

• Change the instrument recording feature, automatic vs. manual (

• To set the high and low alarm (

6ALM

)

• To change the analog voltage output, 1-5V, (

1EGM2Z: 3PMP 4AV 5RECD 6ALM 7VOUT

1EGM

Press 1EGM to set the EGM-4 displays according to intended application. The EG M-4 can be used as a:

1. Stand alone CO

2. CO

IRGA with external sensor (probe) attached (i.e. SRC-1 Soil Respiration

Chamber, CFX-1, CPY-3, HTR-2 RH/T emp/PAR Probe, PAR-1 Sensor, O etc.).

3. Steady State Porometer

If the instrum ent is being used on its own, press key 1. If an external sensor/pr obe is used simultaneously, press k ey 2. If the EGM-4 is being used as a porometer , press key 3. After making your selection, an asterisk (*) will be placed next to your selection. The EGM-4 will automatically recognize which sensor or probe is connec ted by way of code resistors which are built into the sensor connector (See Environmental Sensor Inputs (I/O Por ts) . Pres s the Y key to return to the 2SET menu.

IRGA

1EGM

7VOUT

4AV

5RECD

)

Sensor,

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Operation

Press 2ZERO to change the zero type and the time interval for performing zeros.

Changing the Zero Type

Press key 2 (2ZERO) and then key 1 to change the zero type used by the EGM-4. At present, there are 3 types of zeros that can be performed:

Auto

Manual

EXT

An asterisk (*) indicates which ZERO type is selected. By default, the ZERO TYPE is set to AUTO which is what we recommend.

To change the ZERO TYPE, press k ey 1 for AUTO, k ey 2 for MANUAL or key 3 for EXT. Immediately after pressing the k ey, the asterisk (*) will be displayed next to your selection. This will be the ZERO TYPE that will be used by the EGM-4 until changed again. Press key Y to return to the 2SET menu.

This is the recom mended ZERO type. The EGM-4 performs a Zero on start up, then again after 2 minutes, then again after 4 mor e minutes, then after 8, etc up to a maxim um inter val set by the ZEROTIME. ZEROT IME by default at start up is 20 minutes but it can be set from 1 to 30 minutes. This is the default m ode on startup. If selected, the EGM-4 will perform an initial ZERO when first s tarted. After that, the user is responsible for performing ZEROS by pressing the 0 key while in Measurement Mode.

minutes, one will be performed automatically.

A ZERO can be initiated by pulling DATA/ZERO REQ (Pin 10) line LOW. (Connect to Ground Pin 8) Hold for 3 sec onds and then break ground connection.

If no ZERO occurs after 40 minutes, one will be performed automatically.

Note, if the user fails to perform a ZERO after 40

ZEROTYPE *:AUTO 2:MANUAL 3:EXT

Changing the Zero Time

Press key 1 (1ZERO) and then key 2 to change the Auto-Zero time.

Zero time is the interval between Zeros in m inutes when ZERO TYPE is set to Auto. If the displayed time is correct, simply press the Y key. If you want to change the ZERO TIME, press key N and enter a value up to a maximum of 40.

leading zeros are required (i.e. 05 for 5 minutes).

display. To accept, press the Y key.

ZEROTIME = 40 Y=OK N=NEW VAL

Note, for values less than 10,

The new value will be updated on the

3PMP

Press 3PMP to enable/dis able the internal sampling pump. By default, the sample pum p is on.

SAMPLE PUMP ON Y/OK N/CHANGE

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Operation

If required, the internal pump can be turned off by pressing the N key.

If static sam pling is selected, the user can inject sam ples directly into the sample cell rather than having the sample pumped through it. For minimum volume, the samples should be injected into the cell exhaust through the port labelled “G as Out”. A minimum volume would be about 5 ml. A warning is given 2 minutes and 1 m inute prior to the instrum ent perfor ming a ZERO followed by the pump turning on for a ZERO. On com pletion of the Analyser ZERO, the pump will again switch off.

STATIC SAMPLING Y/OK N/CHANGE

4AV

The outputs from the CO2 sensors are normally subjected to an averaging process. This consists of diff erencing the c urrent r eading and the stored average r eading (both raw data). If the difference exceeds the average limit, then the current reading replaces the average. Otherwise, the current reading is incorpor ated into the average. The average reading is then linearized etc. to give the measured concentration. If AV is s et to 0, then aver aging is dis abled giving instantaneous readings. The averaging band is increased as AV is increased, up to a maximum of 999 units.

The AV is automatically set to 1 unit for s oil respiration and static sampling measurements. The AV defaults to 30 units without a probe.

Press 4AV to change the AV.

If you want to change the AV value, press key N and enter a value up to a maximum of 999.

AV. LIMIT = 30 Y/OK N=NEW VAL

5RECD

This controls the recording in the EGM-4. Records can be recorded manually or automatically at set time intervals. Press Key 5 to set the recording type.

To change the r ecording from MANUAL (M) to AUT OMATIC (A) and vic e versa, press k ey 1. If M is displayed, the time interval (2INT) is set 0 by default. A key press of 1 will change the recording type to A (Automatic) and the time inter val (2INT) will change to 1 (1 minute) by default. To change the time inter val for automatic recording, press key 2 and enter a value (not to exceed 720 minutes).

(i.e. 005 for 5 minutes).

The EGM-4 is set to MANUAL recording by default.

1REC:M 2INT: 0

Note, leading zeros are required fo r values less than 100

6ALM

There are both high and low alarm facilities built into the EGM-4. A 2 pin header type connector (CN6) is located on the internal EG M-4 circuit board for controlling the alarm . All EGM-4’s are cur rently supplied with the alarm dis abled as the jumper is f itted to just one pin

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Operation

on CN6. To enable the alarm, simply fit the jumper to both pins on CN6. For acc ess and location of CN6, see Inside The EGM-4. Note, the alarm facilities are not available with Probe Types 7 or higher (i.e. porometer and soil res piration). Press key 3 to set the Low and High CO

alarm setpoints.

1:LOCO2 = 250 2:HICO2 = 2000

Setting the Low CO2 Alarm Setpoint

Press key 3 (3ALM) and key 1 to set the low CO2 alarm setpoint in ppm . The display will show ?????. Enter the required value.

than 1000 (i.e. 00200 for 200).

setting of 250 ppm . The reas on for this is that a typical low CO the following scenarios:

• Low or no air flow.

• Absorber column exhausted (soda lime).

• Zero valve failure.

• Source failure.

However, past history has shown that some customers want to work at lower CO concentrations. As a result, lower alarm settings can be set up by the user if requir ed. If the low alarm is set to 250 ppm, the low alarm operates when the self-check ing facility finds any of the following system faults:

Error Code Reported fault

1 Zero to low 2 CO2 < 250 ppm 3 Analyser temperature out of range (too cold) 4 Analyser temperature out of range (too hot) 5 RH > 90%

The above error codes are ac companied by corresponding displays and the error codes are written to the records. Note, with the porom eter and soil respiration chambers (SRC-1 and CFX-1), the display warnings still occur but there is no alarm.

The low alarm signal comes out on Pin 7 and is buffered (i.e. able to drive a load).

Note, leading zeros are required for values less

The EGM-4 is supplied with a factory default low alarm

value is the result of one of

Setting the High CO2 Alarm Setpoint

Press key 2 to set the high CO2 alarm setpoint. The display will show ?????. Enter the required value.

The default EGM-4 high alarm setpoint setting is 2000. As long as the high alarm is set

900).

to the maximum CO value, when the CO

Note, leading zeros are required fo r values less than 1000 (i.e. 00900 for

ppm range of the instrum ent, the alarm is inactive. If set to a lower

concentration exceeds the high setting, the alarm will activate.

The high alarm signal comes out on Pin 13 and is not buffered.

7VOUT

Press key 7 (7VOUT) to check/set the analog voltage output. These settings control the voltage output from the D/A converter in the EGM-4.

EGM-4 Operator's Manual – Version 1.00

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Operation

Where: D/A 1V Selects the maximum voltage output of the EGM-4 (1-5V)

2000 Corresponds to the CO2 concentration (ppm). The FSD (Full Scale Deflection) analog output value can be set from 1 to 5V. Press key 1

and enter any value between 1 and 5 to set the analog output to the value required. Press key 2 if you want to change the CO

concentration corresponding to the analog output value.

As in the display above, the EGM-4 would be set up with an analog output of 0-1V corresponding to a measurement range of 0-2,000 ppm.

By default, the analog voltage output is 0-5V. If the displayed values are correct, simply press the Y key to return to the 2SET menu.

Note. The voltage output must be set to 5V in order for the current output (4-20 mA) to work properly. If the voltage output is changed to any other value (i.e. 2, 3 or 4V), the current output facility will not work correctly and should not be used.

3CAL

To calibrate the EGM-4, press key 3.

The EGM-4 will display a value. Before proceeding, it is critical that:

• The absorber column is properly seated in its manifold

• The soda lime is fresh.

• The EGM-4 has been on for at least 30 minutes.

• The Gas Out port is unobstructed.

Connecting Calibration Gas To The EGM-4

During calibration, the signal from the CO2 detector is referenced against a gas of k nown CO2 concentration. The EGM-4 calibration procedure uses two reference points:

1. Zero CO

2. Span Gas (a user-defined CO

composition).

It is therefore vital that both of these references ar e accurate. For greater accuracy, cylinder mixtures should be acc urate to +/- 1% and traceable to NIST standards. The zero gas will only be accurate if the soda lime in the absorber column is fresh.

Assuming that a calibration gas mixture is used to calibrate the EGM-4, follow these instructions:

1. To avoid excess pres sure in the sample cell and possible damage to the Analyser, you

must connect the s ample line with a “T” piece between the calibration gas mixture and the “Gas In” port on the EGM-4 as follows:

(generated from air that has been scrubbed through soda lime).

CO2 CONC = 2000 CORRECT (Y-N)?

concentration, normally a cylinder of certified CO2

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Operation

Gas In

Port

Excess gas o approx. 250 ml/min

Pressure

Regulator

EGM-4

In-line “T” piece

to vent excess

Shut-Off

Valve

CO2 Gas

Cylinder

2. T he pressure regulator should be s et to a very low pressure and there should be a slight

flow excess gas venting from the open “T” Piece (approx. 250 ml/min).

3. Press key N and enter the CO

This value must m atch the certified CO

concentration of the calibration gas that you are using.

concentration of the calibration cylinder and be

similar or higher than the anticipated m easurement range of the instrument (i.e. it is best to calibrate the instrument with a reference gas containing 350 - 450 ppm CO measuring around 350 ppm CO

when

4. The EGM-4 will then perform a ZERO. At completion of successful ZERO, a similar

message to the following will be displayed.

CO2 CONC = 1050 KEY0 WHEN STEADY

5. At this point, all you are looking for is that the CO

displayed value may not be the value you entered in step 1 above.

concentration is steady.

When this value

Note, the

is steady (i.e. not changing by more than 1 ppm after 30 seconds), press the 0 key.

6. Calibration is complete. The new calibration and linearization constants are stored in

non-volatile memory.

4DMP

Press key 4 to view/transmit stored data.

Stored data can be viewed on the instr um ent LCD display or transm itted to your PC computer using our data transfer sof tware. The EG M-4 will store up to 1,000 records in memory.

when the memory is full, the oldest record will be overwritten each time additional records are taken.

1:SCREEN DISPLAY

2:DATA DUMP 1-2?

Note,

Screen Display

To view stored data on the LCD display, press key 1. The latest stored record is displayed first. Each record has 3 different displays associated with it as follows:

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Operation

Display 1

REC 0000 PLOT 01 04-01 11:52

Where:

Record Number

REC PLOT 04-01 11:52

Plot Number Date (4

Time

day of January)

Press the 8/X key to proceed to the next display:

Display 2

A0000 B0000 C0000 D0000 E0000

Where:

mV signal from sensor (Pin 1).

A B C D E

mV signal from sensor (Pin 2). mV signal from sensor (Pin 3).

mV signal from sensor (Pin 4).

mV signal from sensor (Pin 5).

Press the 8/X key to proceed to the next display:

Display 3

C 950 A 0992 P00

Where:

Atmospheric Pressure

Probe Type

(ppm)

A key press of 8 steps you through the 3 above displays before taking you to the next record in memor y. Af ter all rec ords have been displayed, a mess age “No Mor e Records In Store” is displayed before returning you to the Main Menu.

from one display to the same di splay for the previous record

Note. A key press of Y will step you

. For instance, if Display 3 of record number 5 is displayed on the LCD, a key press of Y will step you to Display 3 for the previous record (Record 4). Therefore, if you are only interested in viewing the CO concentration for each record:

1. Press key 4 (4DMP).

2. Press key 1 (Screen Display).

3. Press the 8 key to display the CO

concentration for the last stored record.

4. Press the Y key to view previous records.

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Operation

A key press of N ends the screen display.

If there are no stored records, the m essage

Note.

“NO MORE RECORDS IN STORE” will be displayed before returning you to the main menu. Note, some of the displays will vary according the probe type connected.

Data Dump

To transm it stored data from the EGM-4 to a PC, you must use the data transfer cable and software supplied with the system. Step by step instructions on transferring data from the EGM-4 to the PC are contained in the software Help file.

When the RS232 transfer cable is properly connected and after you followed the instructions contained in software, press 4DMP and then key 2 on the EGM-4 to transfer the data. Complete data dump to PC takes approximately 70 seconds. Alternatively, the data dump can be initiated from a PC while the EGM-4 c ontinues to collect data. If ZERO TYPE is NOT set to external control, this can be initiated by a low on the Data Request. There are no displays and the EGM-4 returns to measuring after completion.

Sending <KSP>Z<CR> signifies completion. DATA DUMP may be terminated by pressing key N. Oldest records are always sent first.

Record Structure

A single record consists of 60 digits. Real time and stored data is output in the following format:

M/R Plot

M 1 1 28 1 13 19 968 0 000.0 0000 0000 0000 0000 0000 0000 00 00 991 0 R 1 2 28 1 13 21 930 0 000.0 0000 0000 0000 0000 0000 0000 00 00 991 0 M 1 3 28 1 13 23 956 0 000.0 0000 0000 0000 0000 0000 0000 00 00 991 0 M 1 4 28 1 13 25 941 0 000.0 0000 0000 0000 0000 0000 0000 00 00 991 0 R 1 5 28 1 13 27 946 0 000.0 0000 0000 0000 0000 0000 0000 00 00 991 0

No.

Rec

Day Mo Hr Min CO2

Ref

H20

RHT A B C D E F G

Ref

AP PT

Where:

M/R

M = Real Time Measurement R = Record from memory

Plot No. Rec No. Day Mo Hr Min(utes) CO2 Ref H20 Ref RHT Temp A B C D E F G H AP PT

0-99 1-9999 1-31 1-12 (January - December) 1-24 (based on 24 hour clock) 0-59

reading in parts per million (ppm = µmol mol-1)

O reading in millibars (mb)

Temperature of RH sensor if fitted Temperature (˚C). See

Data Structure Based On Probe/Sensors

See

Data Structure Based On Probe/Sensors

See

Data Structure Based On Probe/Sensors

See

Data Structure Based On Probe/Sensors

See

Data Structure Based On Probe/Sensors

See

Data Structure Based On Probe/Sensors

See

Data Structure Based On Probe/Sensors

See

Data Structure Based On Probe/Sensors

Atmospheric pressure in millibars (mb) Probe Type See

for more information.

1REC

If there are no stored records , the m essage “ NO MORE RECO RDS IN ST ORE” will be

Note.

displayed before returning you to the main menu.

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Operation

Data Structure Based On Probe/Sensors

Please note.

The data structure, particularly columns A-J described above, is dependent

upon the probe/sensor that is connected to the EGM-4.

Probe

Type

0 No Sensor Connected.

1 STP-1 Soil Temperature

2 HTR-2 %RH/Temp/PAR 3 HTR-1 %RH/Temp/LUX 4 PAR-1 Sensor

5 PAR-1 LUX 6 Solarimeter 7 Steady State Porometer

8 SRC-1 Soil Respiration

9 OP-1 Oxygen Sensor 10 50Y %RH/Temp Sensor 11 CFX-1 Open System Soil

11 CPY-3 Canopy

Further description of the data output is as follows:

PAR % RH %

Evaporation Rate mmol m2 s-1 x 1000 Temperature ˚C Flow ml min-1 GS (Stomatal Conductance)

SR Rate (Assimiliation)

DC (Change in CO2 concentration ) DT (Change in time) seconds +/- In column H, if 00 is output, this

Description of Sensor

Connected

The EGM-4 is being used as a stand alone IRGA.

Probe or CH15T RH/T Probe

Probe Probe

(PMR-4)

Chamber

Respiration Chamber

Assimilation Chamber

Output Data Units

µmol m-2 s

mmol (H

A B C D E F G H

mV Pin 1 0000

PAR

0000

PAR

0000

PAR

0000

PAR

0000

PAR

0000

PAR

0000

PAR

0000

-1

O) m

SRC-1: g (CO2) m2 Hour CPY-3 & CFX-1: µmol m

ppm

represents increase in CO2 (respiration). If it is 01, it represents

uptake).

Each Column is described as follows

mV Pin 2 0000

%RH

000.0

%RH

000.0 %RH

0000

%RH

000.0 %RH 0000

Evap Rate 0000

mV Pin 3 0000

Temp.

000.0

Temp.

000.0

Temp.

000.0

Temp

000.0

Temp.

000.0

Temp.

000.0

Temp.

000.0

-1 2 s-1

Pin 4

0000

%RH

Out

000.0 DC

0000

mV Pin 5 0000

Pin 5 0000

Flow

000.0 DT

0000

Flow

000.0

Flow

000.0

In column G, a flow multiplier is output to provide true flow rate (1 or 10).

0000

Rate

00.00

Rate

00.00 SR

Rate

00.00

+/- SR

Flow

Multiplier

Flow

Multiplier

Rate

00=+

01 = -

+/- SR

Rate 00=+

01 = -

+/- SR

Rate 00=+

01 = -

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Operation

Error Codes

Error code infor mation is stored and output with data and can be located at the end of the data string. The following is a list of current Error Codes:

Error

Code

00 Normal Operation Not Applicable Not Applicable 01 Zero read to low

02 CO2 less than 250

03 Analyser

04 Analyser

05 %RH > 90%

06 Battery voltage to

Description Possible Faults Remedy

(<2500)

• Absorber column not properly fitted.

• Exhausted soda lime.

• Zero valve failure.

• Source/detector failure.

• Fit properly into

manifold.

• Change soda lime.

• Contact PP

Systems. (see

PP Systems’ Contact Information

)

• Contact PP Systems. (see

Systems’ Contact

)

ppm

• Genuine low CO

concentration.

• Absorber column not properly fitted.

• Exhausted soda lime.

• Zero valve failure.

• Source/detector failure.

Information

• Not Applicable.

• Fit properly into

manifold.

• Change soda lime.

• Contact PP

Systems. (see

Systems’ Contact Information

• Contact PP Systems. (see

Systems’ Contact

)

temperature < 50 ˚C

• Possible thermostat failure.

Information

• Contact PP Systems. (see

Systems’ Contact

)

temperature > 60 ˚C

• Possible thermostat failure.

Information

• Contact PP Systems. (see

Systems’ Contact

)

• If an RH sensor is fitted, a reading above 90% could mean condensation.

Information

• Contact PP Systems. (see

Systems’ Contact Information

• Battery voltage < 10.5v • Re-charge battery

low

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Operation

EGM Serial Outputs For Use With WINDOWS Data Transfer Program.

On Starting: <SP>B, EGM4,Serial Number, Firmware version<CR>

<SP>=Space, <CR>=Carriage return. Then during the delay period at the start: <SP>I, NN <CR>

Where NN is the same as the count on the EGM display. During Warm up <SP>W,TT<CR>

Where TT is the cell temperature. During ZERO

<SP>Z.NN<CR> Where NN is the same as the EGM display count.

During Diagnostics a data string is transmitted through the RS232: <SP>D,CCCCC,ZZZZZ,HHHH,HTHT,ANLT,INPA,INPB,INPC,INPD,INPE,ATMP<CR >.

(These values are the reads from the A/D converters and have not been scaled.) Where:

CCCCC Current Analyser reading ZZZZZ Stored Analyser reading during last zero. HHHH Reading of the internal humidity sensor (optional). HTHT Reading from the temperature sensor (optional). ANLT Analyser temperature sensor reading. INPA-E Corresponds to the mV inputs from external sensors. ATMP Reading from the pressure transducer (mb).

5CLR

To clear data stored in memory, press key 5.

To clear the entire database, press the Y key twice. For data safety reasons, you will be asked to “Press Key 0 To Confirm”. Press the 0 key to clear. The message “Database Cleared” is displayed before returning you to the main menu. If you do not want to clear the database, simply press the N key.

CLEAR DATABASE

(YY-N)?

6CLK

To view/set the EGM-4 real time c lock, press the 6 key. The following message should be displayed:

EGM-4 Operator's Manual – Version 1.00

RESET TIME (Y-N)?

13-12-01 16:51

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Operation

The date is displayed as day/month/year and the time is displayed on a 24 hour format. The display above shows December 13, 2001 and 4:51 PM. If the time is correct, press the Y key. Otherwise, press key N and enter the appropriate date and time. Leading zeros must be entered if required for date and time (i.e. if the time is 8:00 AM, enter 08 for the hour).

! Note ! Do not fo rget to ent er th e dat e as day/month /year and th e time b ased o n t he 24 hour format.

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Page 37

Diagnostics and Initialisation

The EGM-4 has a diagnostics and “Initialisation” feature built in for troubleshooting and f or setting system controls and calibration bac k to factory default. To check system diagnostics and to reinitialize the EGM-4, press key 0 with the Main Menu displayed. The following message is displayed:

Diagnostics

Press key 1 for system diagnostics and the following will be displayed:

Where:

CR:44049 Reading from 16 bit A/D converter for CO M/Z M indicates that the Analyser is in “Measure” mode. Z indicates that the

Analyser is in “Zero” mode.

1:MEASURE Pres s key 1 to put the EGM-4 into “Measure Mode”. In “Measure” m ode, the

CR value should read approximately 35000-45000 for CO around 400 ppm.

2:ZERO Press key 2 to put the EGM-4 into “Zero” m ode. In “Zero” m ode, the A/D value

for CR should read approxim ately 40000-50000

in the absorber column

greater than the CR value in “Measure” mode.

Press Key N to return to the Main Menu.

1:DIAGNOSTICS 2:INTIALISE

CR:44049 M 1:MEASURE 2:ZERO

. The CR value in “Zero” mode should always be

detector.

concentration

if fresh soda lime is present

Initialisation

This feature is available in the event of a bad or incorrect calibration, if a new EPROM is installed with a new “Checksum” value, or if the system locks up. Pres s key 2 to reinitialize the EGM-4.

records to your PC or they will be lost for good. All records will be cleared from system memory during Initialisation.

After pressing k ey 2, you will be presented with ???? on the display. At this point, enter the code 0462. This will follow with a “Database Cleared” message before returning you to the Main Menu. At this point, your system will be returned to its or iginal factor y default conditions (i.e. calibration, etc.). The EGM-4 system settings will automatically revert to:

Calibration

Concentration Recording Type Zero Type Checksum Analog Voltage Output Memory

Very Important. Before initializing the EGM-4, you must dump all stored

2000 ppm Manual. No averaging of data.

Automatic 123456 5

Reset to start of memory.

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Page 38

Maintenance

The EGM-4 is virtually maintenance free. However, there are a few items that should be watched and cared for periodically.

Soda Lime Absorber Column

The soda lime absorber column is built into the EGM-4 and safely protected within the enclosure. It should not require any maintenance with the exception of the soda lime desiccant which will require replacement from time to time (See aluminium cap, located on the back of the instrument, is fitted with an “O” ring with a grey foam filter between it and the desiccant. The “O” ring should be kept fresh by applying a slight smear of silicone grease f rom time to time. If this “O” ring gets to dry, it could crack or even break which will lead to a leak in the system and errors in Analyser ZERO. The black aluminium cap can then be removed and the contents emptied when required. When replacing the soda lim e, the column should be tapped to ensure tight packing and the cap replaced as found. O ver time, the grey foam filter may require replacement. If so, contac t PP Systems (

It is sensible to examine the absorber column each time the contents are replaced as any leakage of am bient air into the gas circuit generally causes er ror m essages dur ing “Autozero” operation or fluctuating CO

PP Systems’ Contact Information

concentration during measurement.

Soda Lime

). The black

Soda Lime

Soda Lime is supplied as s elf-indicating granules (1-2.5m m) which turn from green to brown as it becomes exhausted. T his desiccant should be replaced when it is two-thirds exhausted (brown). Soda Lime cannot be regenerated and should be discarded when exhausted. Frequent replacement should not be required under normal circ umstances. The amount of change is highly dependent on the “Auto-Zero” frequency. Under normal operating conditions, this desiccant is changed approximately 1 time per month. See

For accurate m easurements and c alibration, it is absolutely critical that the EGM-4 absorber column is not exhausted. If the soda lime is becom ing exhausted, it will cause the ZERO to be performed on non-ZERO air causing an error in the calibration.

Soda Lime

! CAUTION !

WASH YOUR HANDS AFTER HANDLING SODA LIME

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Maintenance

MATERIAL SAFETY DATA FOR SODA LIME

CHEMICAL COMPOSITION

Components % W/W Calcium Hydroxide (Ca(OH)2) > 75.5% Sodium Hydroxide (NaOH) < 3.5% Water < 21.0% Indicator (Inorganic Salt) < 0.2%

PHYSICO-CHEMICAL DATA

Form Granules Color Green (Exhausted : Brown) Odor None Bulk Density 0.9 g/cm3 Solubility in Water None pH in Water 12-14 Incompatible Substances Acids, Chloroform, Trichlorethylene

Hazardous Decomposition

Products None

PROTECTIVE MEASURES, STORAGE AND HANDLING

Storage Conditions Clean dry environment Preferred temperature range 0 - 35 ˚C. Store away from direct heat/sun. Protective Measures Avoid inhaling dust. Wash hands after handling Industrial Hygiene Keep containers closed. Keep contents dry.

MEASURES IN CASE OF ACCIDENTS AND FIRES

Spillage Contain material.

Sweep or vacuum up. Transfer solids to metal or plastic container for disposal. Wash down spillage with water.

Suit. Extinguishing Media Water, CO2, Powder, Foam, Halon.

FIRST AID

Inhalation Remove from exposure. Skin Contact Drench with clean water. Eye Contact Irrigate thoroughly with clean water. Ingestion Wash out mouth thoroughly.

HAZARD LABELLING

Transport Codes None required. Hazard Classification None.

Obtain medical attention if discomfort persists. Obtain medical attention if skin becomes inflamed. Obtain medical attention. Drink water.

Obtain medical attention.

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Maintenance

Servicing The EGM-4

Fuse

The EGM-4 circuitry is protected by a 1A (5x20mm) fuse. This is located in a black fuse holder located at the back of the instrument (see replacement, please ensure that the correct size and type of fuse is used.

It is very easy to determine if a fuse is good or bad. Usually, a bad fuse will be burned out and visually obvious. The true test is to use an ohm m eter. Place one lead from the ohm meter on one end of the fuse and the other lead on the opposite end of the fuse. If it reads 0, you have a good fuse. Anything else, the fuse is bad and should be replaced.

The EGM-4 enclosure must be removed in order to service the following items:

• Infrared Source

• EPROM

• Zero Valve

• 12V Lead Acid Battery

• Air Sampling Pump

Remove These 4 Screws To Access Internal EGM-4 Components

Back Of EGM-4

). If this requires

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Maintenance

Air Sample Pump

CN6 (Alarm)

Infrared Source

Zero Valve

Air Out

Air In

Front Panel Retaining Nuts

Real Time Clock

EPROM

Notch On EPROM

Current Output

(CN7, IOut)

Rear Panel Retaining Nuts/Screws

Inside The EGM-4

Infrared Source

The infrared source should last for many years and not require replacem ent. The obvious sign of failure is that it is not flashing when the system is powered. However, it can be replaced easily if required. To do so:

1. Disconnect the infrared source electrical connector located at CN13 by pulling up on it.

2. Rem ove the 4 s mall scr ews that secure the infrared s ource to the end of the sam ple cell and remove it. Fit the new infrared source to the end of the sam ple cell aligned to fit in the notch in the

sample tube and secure it in plac e by the 4 small screws.

the bulb with your fingers and do not overtighten the scr ews.

4. Connect the new infrared source electrical connector to CN13 on PC075 circuit board. The orientation does not matter.

Be very careful not to touch

EPROM

The firmware and f actory meas ured calibration f actor s f or the EGM-4 ar e stored on a mem ory chip commonly referred to as an EPROM inside the instrument. This should never require maintenance but it may need to be replaced if the system is upgraded.

The EPROM that is used in the EGM-4 m ust be protected fr om static electr icity. As a result, there are several precautions that the cus tomer should take before removing EPROMS. The risk of dam age can be minimized by earthing both the operator and the lab bench surface. This can be done by covering the surface of the bench with a conductive material (e.g. aluminium foil) that is electr ically connected to an earthing point suc h as a m etal water pipe or tap. The operator should also be earthed using a wrist strap or by holding a wire that is connected to the same earthed point. Please contact PP Systems for further information.

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Maintenance

Once suitable earthing arrangem ents have been made, the EGM-4 enclosure can be opened to gain access to the circuit board containing the EPROM. The position of the EPROM is shown above.

Each EPROM is located in a specific orientation. Befor e starting to rem ove the chip, note the position of the notch on the end of the chip relative to the rest of the instrument. Using a small, flat screwdriver, gently pry the EPROM up until it is rem oved from its socket. W hen fitting the new EPROM to the socket, be caref ul not to bend any pins. Place the EPROM in the socket (noting the notch on one end of the EPRO M) and gently press down to secure in place.

Very Important.

Error! Reference source not found.

After replacing the EPROM, you should reinitialize the instrument (See

ZERO Valve

If it is suspected that the ZERO valve is not functioning pr operly, we recomm end r eturning the EGM-4 to our f actory for repair as this item is soldered directly to the PC075 circuit board. Contact PP Systems (see

PP Systems’ Contact Information

12V Lead Acid Battery

The 12V 2.0 Ah s ealed, rechargeable, lead acid battery should last for sever al years as long as it is properly maintained. Based on manufacturer’s data, the battery is non-spillable (qualified to non-spillable UN2800 standards) and can be used in any orientation. It has a float design life of 5 years. It s hould be c hecked periodically to ensure that it takes up charge. Measuring the voltage across the term inals of the battery after it has been char ged overnight can assess this.

If the battery is not fully charged after 12 hours, first c heck that the 1A fuse is ok. This fuse protects the charging circuit and if blown, the internal battery will not take a charge.

Please Note.

The internal 12V battery should always be fully charged before long-term storage. If it is stored in a low or discharged state, it is possible that it will become deepdischarged. If this occur s, the charge capacity of the battery is permanently reduced and will require replacement.

Battery Specification

Manufacturer Yuasa Type NP2-12 Voltage 12V Nominal Capacity @ 20 hr.rate (Ah) Terminals Faston Tab 0.187” Housing ABS Resin Dimensions 3.50” x 5.91” x .79” Weight 1.54 Lbs.

2.0 Ah

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Maintenance

Removing The 12V Battery

The front panel may need to be removed to slide the battery out of its com partment if it is stuck. W hen removing the battery, first ensur e that the power to the EGM-4 is turned off. Next, remove the red (positive) and blue (negative) charger leads from the battery.

Slide the new battery into the battery compartment, connect the charger leads correctly (Red = Positive, Black = Negative) and refit the enclosure.

Red (Positive) Charger Lead Blue (Negative) Charger Lead

If the battery is stuck, r emove the front panel retaining nuts, gently pull panel forwards, and push back of battery through hole provided.

Air Sampling Pump

The EGM-4 is fitted with a sealed, rotary vane pumps to sam ple the reference air. Rotary vane pump components wear with prolonged use and m aterial from the vanes m ay build up within the pumps. T his can eventually reduce the pumping efficienc y or even cause them to seize. The normal signs of a bad pump are as follows:

A worn pump usually sounds rough or vibrates.

Noise. Temperature.

The outer casing is hot when touched with your fingers.

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Maintenance

Replacing The Air Sampling Pump

It is very easy to replace a bad air sampling pump. First, tr ace the electr ical connec tion to the pump and disconnect the 2-pin connector from the terminal on the EGM-4 circuit board. Secondly, the electrical connector is rem oved by gently bending back the connector lock and sliding out the connector.

correct re-fitting of the pump

Please note the orientation of the red and black wire for

. The pump itself is secured in position by the gas tubing connections. Finally, remove the tubing from the inlet and outlet ports on the pump and lift out.

Fit the new pump making sure that:

1. The flat back part of the pump sits flush on its manifold.

2. Connec t the inlet tubing to the inlet port and the outlet tubing to the outlet port on the pump.

3. Finally, the 2-pin electrical connector s hould be reconnected in the same orientation. The two notches on the connector latch with the corresponding lock.

Cleaning The Air Sampling Pump

During prolonged operation, the vanes inside the pump will wear and deposit material inside the pump. It is sensible to clean the pump by periodically flushing it with with isopropyl alcohol. The following procedure can be adopted:

1. Connect the pump to a 6-12V source and fit a 30mm tube to the pump inlet. (i.e. the EGM-4 can be used to supply power via the pump electrical connector.

however, essential that the flu shing is p erformed ou tside of the instrument to avoi d spillage into it

2. Hold the pump above a beaker of isopropyl alcohol and dip the tube into the alcohol (See below). Run the pump to draw alcohol through it. A small roll of cotton wool in the inlet pipe can act as a filter for the re-circulating alcohol.

It is,

Pump

Electrical

Connector

Alcohol

If the pump is seized, it may be freed by tapping it on the bench or by reversing the voltage to run it backwards.

3. Run alcohol through the pum p for a m inute or two to ensure that any material is removed. When f inished, run the pump in air for at least 15 m inutes to allow any residual alcohol to eVapourate. Ideally, let the pumps dry outside of the EGM-4 overnight. If the pum ps are reconnected prematurely, the absorber chemical (soda lime) will be exhausted quicker than usual.

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Page 45

Maintenance

In-Line Hydrophobic Filter

If the In-Line Hydrophobic Filter is used with the EGM-4, it is very important to periodically inspect the internal filter and “O” Ring. To check the internal filter:

1. Open the filter holder.

2. Remove internal “O” Ring using a fine screwdriver or similar tool.

3. Remove the internal 3 m icr on, hydrophobic filter and inspect f or dir t, dust or m ois ture. If there is any sign of dirt, dust or moisture, replace the filter.

If a new filter is f itted, place the filter in the holder, place a slight s mear of silic one grease on the “O” ring and fit the “O” ring inside the holder to s ecure the filter in place. Refit the other end of the holder and tighten.

Important Note

The “O” r ing must always be used with the in-line holder to ensure leak tight seal. Tak e care not to apply too much silicone grease to the “O” ring as this could contaminate the filter.

“O” Ring

3 micron, hydrophobic

filter

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