Edwards AIM-SI1-NW25 User manual

D146-71-880
Issue E
Original Instructions
Instruction Manual
Industrial Active Inverted Magnetron Gauge
Description Item Number
AIM-SI1-NW25 D146-71-000
AIM-XI1-NW25 D146-72-000
AIM-SLI1-NW25 D146-74-000
AIM-XLI1-NW25 D146-75-000

This product has been manufactured under a quality management system certified to ISO 9001:2008
Declaration of Conformity
We, Edwards Limited,
Crawley Business Quarter,
Manor Royal,
Crawley,
West Sussex, RH10 9LW, UK
declare under our sole responsibility, as manufacturer and person within the EU authorised
to assemble the technical file, that the product(s)
AIM-SI1-NW25 D146-71-000
AIM-XI1-NW25 D146-72-000
AIM-SLI1-NW25 D146-74-000
AIM-XLI1-NW25 D146-75-000
to which this declaration relates is in conformity with the following standard(s) or other
normative document(s)
EN61010-1: 2010 Safety Requirements for Electrical Equipment for Measurement,
Control and Laboratory Use. General Requirements
EN61326-2-3: 2013 Electrical equipment for measurement, control and laboratory
(Class B Emissions, Use. EMC requirements. Particular requirements. Test
Industrial Immunity) configuration, operational conditions and performance criteria
for transducers with integrated or remote signal conditioning
EN50581: 2012 Technical Documentation for the Assessment of Electrical and
Electronic Products with respect to the Restriction of Hazardous
Substances
and fulfils all the relevant provisions of
2014/30/EU Electromagnetic Compatibility (EMC) Directive
2012/19/EU Waste from Electrical and Electronic Equipment (WEEE) Directive
2011/65/EU Restriction of Certain Hazardous Substances (RoHS) Directive
Note: This declaration covers all product serial numbers from the date this Declaration was
signed onwards.
19.08.2015, Eastbourne
Larry Marini, Senior Technical Manage
r
Date and Place
P200-02-040 Issue
F

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Contents
D146-71-880 Issue E
Contents
Section Page
1 Introduction .......................................................................................1
1.1 Scope and definitions ................................................................................................... 1
1.2 General description ..................................................................................................... 1
1.3 Gas dependency .......................................................................................................... 2
2 Technical data ....................................................................................3
2.1 Mechanical data .......................................................................................................... 3
2.2 Performance, operating and storage conditions .................................................................... 3
2.3 Electrical data ............................................................................................................ 3
2.4 Error monitoring ......................................................................................................... 4
2.5 Materials exposed to vacuum .......................................................................................... 4
3 Installation .........................................................................................5
3.1 Unpack and inspect ...................................................................................................... 5
3.2 Fit the AIM gauge to the vacuum system ............................................................................. 5
3.3 Electrical connection .................................................................................................... 5
3.3.1 Connect to Edwards controllers or AGD display ..................................................................... 5
3.3.2 Connect to your own supply and control equipment ............................................................... 6
4 Operation ..........................................................................................9
4.1 Safety ......................................................................................................................9
4.2 Enable and disable the AIM gauge ..................................................................................... 9
4.3 Pressure measurement .................................................................................................. 9
4.4 Set-point .................................................................................................................10
5 Maintenance ..................................................................................... 13
5.1 Introduction .............................................................................................................13
5.2 Replace the body tube .................................................................................................13
5.2.1 Remove the AIM gauge from the vacuum system ..................................................................13
5.2.2 Fit the new body tube .................................................................................................13
5.2.3 Refit the AIM gauge to the vacuum system .........................................................................13
5.3 Replace the electrode assembly ......................................................................................14
5.4 Replace the electronics and magnet housing ......................................................................14
5.5 Clean the internal components .......................................................................................15
5.6 Fault finding .............................................................................................................15
6 Storage and disposal ........................................................................... 17
6.1 Storage ...................................................................................................................17
6.2 Disposal ...................................................................................................................17
7 Spares and accessories ......................................................................... 19
7.1 Introduction .............................................................................................................19
7.2 Spares .....................................................................................................................19
7.3 Accessories ...............................................................................................................19
Index .............................................................................................. 21
For return of equipment, complete the HS Forms at the end of this manual.
dcs/7692/07/15

D146-71-880 Issue E
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Contents
Illustrations
Figure Page
1 General view of the AIM gauge (showing the NW25 flange) ....................................................... 2
2 Dimensions (mm) ........................................................................................................ 4
3 Schematic diagram of typical electrical connections .............................................................. 6
4 Exploded view of the AIM gauge tube assembly ...................................................................15
Tables
Table Page
1 Pins on the AIM gauge electrical connector socket ................................................................. 7
2 Pressure and voltage characteristics for nitrogen and dry air ...................................................10

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Introduction
D146-71-880 Issue E
1Introduction
1.1 Scope and definitions
This manual provides installation, operation, maintenance and storage instructions for the Edwards Industrial Active
Inverted Magnetron Gauge. You must use the gauge as specified in this manual.
Read this manual before you install and operate the gauge. Important safety information is highlighted as WARNING
and CAUTION instructions; you must obey these instructions. The use of WARNINGS and CAUTIONS is defined below.
CAUTION
Cautions are given where failure to observe the instruction could result in damage to the equipment, associated
equipment and process.
Throughout this manual, page, figure and table numbers are sequential.
The units used throughout this manual conform to the SI international system of units of measurement.
The following symbol appears on the AIM Gauge:
1.2 General description
The AIM Gauge, shown in Figure 1, is an inverted magnetron gauge head and gauge controller in a single compact
unit. The gauge operates as a cold cathode ionisation gauge, in which the pressure is measured indirectly as function
of the current which flows in a Townsend discharge maintained in the body tube.
The measurement range of the gauge is 1 x 10-8 to 1 x 10-2 mbar (AIM-SI1/AIM-SLI1) and 1 x 10-9 to 1 x 10-2 mbar
(AIM-XI1 /AIM-XLI1). The AIM Gauge vacuum connection is a NW25 flange.
The AIM Gauge requires a 13.5 to 36 V d.c. power supply; it has a 2 to 10 V d.c. analogue output which is related to
pressure. The AIM Gauge is compatible with all of the Edwards TIC (Turbo Instrument Controller), ADD (Active Digital
Display) and with the appropriate versions of the Edwards AGD’s (Active Gauge Displays). Alternatively, you can read
the AIM Gauge output signal with a voltmeter or analogue-to-digital converter.
We recommend that you do not operate the AIM Gauge unless the pressure in the vacuum system is 1 x 10-2 mbar or
lower. A gauge enable signal is used to control the operation of the AIM Gauge; refer to Section 4.2 for more
information.
An 8-way electrical connector socket on the AIM Gauge (Figure 1, item 7) is used to connect the AIM Gauge to your
TIC, ADD, AGD or electrical supply and voltmeter. Electrical cables fitted with suitable connector plugs are available
as accessories.
A gauge identification signal is available on the electrical connector; this signal is used by Edwards Controllers to
identify which type of Active Gauge is connected.
The AIM Gauge has a set-point facility; the set-point signal is an open drain transistor (FET) output, which is on when
the pressure measured by the Gauge is below a pre-set pressure. You can adjust the pressure at which the set-point
output goes on; refer to Section 4.4.
WARNING
Warnings are given where failure to observe the instruction could result in injury or death to
people.
Edwards offer European customers a recycling service.

D146-71-880 Issue E
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Introduction
Note: If you use an Edwards TIC Controller, ADD Controller or AGD Display, the AIM Gauge set-point output signal
is not used.
1.3 Gas dependency
The ionisation of the gas in the vacuum system is dependent on both the pressure and the physical properties of the
gas. Therefore, the output signal of the AIM Gauge is gas dependent.
The output signal voltage to pressure conversions in Section 4.3 apply for nitrogen and dry air.
Calibration graphs for use with argon, neon, krypton, helium and carbon dioxide are available on request; contact
your supplier or Edwards.
Figure 1 - General view of the AIM gauge (showing the NW25 flange)
1. End-cap
2. Vacuum flange
3. Body tube
4. Magnet housing
5. Cable connector plug
6. Set-point potentiometer (on end of item 1)
7. AIM Gauge connector socket

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Technical data
D146-71-880 Issue E
2Technicaldata
2.1 Mechanical data
2.2 Performance, operating and storage conditions
2.3 Electrical data
Dimensions See Figure 2
Mass 840 g
Volume of gauge tube 26 cm2
Enclosure rating IP40
Ambient temperature
Operation 5 to 60°C
Storage 0 to 70°C
Ambient humidity (operation) 10 to 90% (non condensing)
Maximum operating altitude 2000 m
Maximum internal pressure 10 bar absolute (9 bar gauge)
Pressure measurement range 1 x 10-8 to 1 x 10-2 mbar (AIM-SI1/AIM-SLI1)
1 x 10-9 to 1 x 10-2 mbar (AIM-XI1/AIM-XLI1)
Pollution category EN61010 Category 2
Voltage +13.5 to +36 V d.c.
Max voltage ripple 1 V peak to peak
Max source resistance 50 
Max power consumption 2 W
Electrical connector FCC68/RJ45 type, 8-way
Pressure output signal
Range 2 output 10 V d.c.
Error range output < 2 V d.c. or output > 10 V d.c.
Impedance 0.1 
Min load impedance 10 k
Max current source 1 mA
Gauge enable
Control sense Active low
Active level < 1.3 V
Control impedance 12 kpull up to positive supply
Set-point output external load rating 40 V d.c., 100 mA max
Set-point trip level
Range 1.8 to 10.0 V
Minimum load impedance 200 k
Hysteresis 500 mV

D146-71-880 Issue E
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Technical data
2.4 Error monitoring
The set-point output is switched off:
for 0.5 seconds during gauge switch on
when pressure output signal voltage < 1.8 V
2.5 Materials exposed to vacuum
Stainless steel (AISI 304, 416 and 347)
Fluoroelastomer
Soda lime glass
Figure 2 - Dimensions (mm)
Back EMF suppression diode*
Min. surge rating 1 A
Min. reverse voltage rating 100 V
Gauge identification resistance 100 k2% AIM-SI1/AIM-SLI1
110 k2% AIM-XI1/AIM-XLI1
*Required when you use an external d.c. relay connected to the set-point output.
1. Clearance required for electrical cable

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Installation
D146-71-880 Issue E
3 Installation
3.1 Unpack and inspect
Remove all packing materials and protective covers and check the AIM Gauge. If the AIM Gauge is damaged, notify
your supplier and the carrier in writing within three days; state the Item Number of the AIM Gauge together with your
order number and your supplier’s invoice number. Retain all packing materials for inspection. Do not use the AIM
Gauge if it is damaged.
If the AIM Gauge is not to be used immediately, replace the protective covers.
Store the AIM Gauge in suitable conditions as described in Section 6.
Note: Please consult your supplier in case of any difficulty.
3.2 Fit the AIM gauge to the vacuum system
The AIM Gauge can be mounted in any orientation. To avoid the build up of debris or condensable material in the
body tube of the AIM Gauge (which will probably cause pressure measurement errors), we recommend that you install
the AIM Gauge vertically as shown in Figure 2.
Use an O-ring/centring ring or co-seal and clamp to connect the NW25 flange of the AIM Gauge to a similar flange on
your vacuum system.
If required, you can turn the end cap (relative to the magnet housing) so that the electrical connection socket is in
a convenient position on your system; refer to Figure 1 and use the following procedure: hold the magnet housing (4)
and turn the end cap (1) in a clockwise or anti-clockwise direction (arrow B) until the electrical connection socket
(7) is in the required position.
3.3 Electrical connection
When using a cable longer than 30 m, full compliance with European Standards requires an in-line surge suppressor
(please refer to Section 7.3).
Note: Ensure the cable is installed in such a way as to not cause a trip hazard.
3.3.1 Connect to Edwards controllers or AGD display
Connect the AIM Gauge to the controller or display with a cable which is terminated in suitable connectors. Suitable
cables are available from Edwards (refer to Section 7).
WARNING
The AIM gauge incorporates magnets. Keep away from heart pacemakers, computers, credit cards
and any other magnetically sensitive devices.
WARNING
If the AIM Gauge malfunctions, the AIM Gauge pressure output may be incorrect. If such a failure
could cause injury to people or damage equipment, you must install a suitable control system to
indicate the failure and, if necessary, to close down your process system.

D146-71-880 Issue E
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Installation
3.3.2 Connect to your own supply and control equipment
Note: Do not connect the electrical supply common (pin 2) to the signal common (pin 5). If you do, the AIM Gauge
pressure output signal will be inaccurate.
A schematic diagram of the recommended electrical connections to the AIM Gauge is shown in Figure 3.
The pins on the AIM Gauge electrical connection socket are used as shown in Table 1. The specification of the
electrical supply, d.c. relay and back EMF suppression diode are given in Section 2.
The connection to pin 6 is optional. Make the connection to pin 6 if you want to connect the set-point output signal
to a d.c. relay; you must connect a suppression diode between pins 1 and 6 to protect the AIM Gauge from transient
voltages generated when the d.c. relay is switched off.
You can connect a voltmeter between pins 5 and 8 to measure the set-point trip level (that is, the voltage at which
the set-point output will go on); see Figure 3.
Connect a switch between pins 2 and 7 to enable and disable the gauge (refer to Section 4.2). If you want to measure
the gauge identification signal (which identifies the AIM Gauge), measure the resistance between pins 4 and 5.
Figure 3 - Schematic diagram of typical electrical connections
1. AIM gauge electrical connector
socket
2. Cable electrical connector plug
3. Electrical supply
4. Voltmeter (pressure signal)
5. D.C. relay (optional)
6. Back EMF suppression diode (optional)
7. Gauge enable switch
8. Voltmeter (set-point trip level)

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Installation
D146-71-880 Issue E
Table 1 - Pins on the AIM gauge electrical connector socket
Pin Number Use
1 Electrical supply positive voltage
2 Electrical supply common
3 Pressure measurement output signal
4 Gauge identification signal
5 Signal common
6 Set-point output signal
7 Gauge enable
8Set-pointtriplevel

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Operation
D146-71-880 Issue E
4 Operation
4.1 Safety
4.2 Enable and disable the AIM gauge
CAUTION
Do not operate the AIM Gauge for long periods when the system pressure is above 1 x 10-2 mbar. If you do the
anode pin can be damaged and the AIM Gauge can be severely contaminated.
We recommend that you only enable the AIM Gauge when the system pressure is lower than 1 x 10-2 mbar and that
you disable the gauge when the system pressure is 1 x 10-2 mbar or higher.
If you have connected the AIM Gauge to an Edwards Controller, refer to the corresponding instruction manual for
details of how to enable (switch on) and disable (switch off) the AIM Gauge.
Otherwise, to enable (switch on) the AIM Gauge, connect pin 7 to pin 2 (or to ground). To disable (switch off) the AIM
Gauge, disconnect pin 7 from pin 2 (or from ground).
4.3 Pressure measurement
If you connected the AIM Gauge to an Edwards Controller, the pressure measured by the AIM Gauge is shown on the
display.
If you connected the signal output of the AIM Gauge to a voltmeter, convert the measured voltage to the
corresponding pressure value: for AIM-SI1 and AIM-SL1, refer to Table 2; for AIM-XI1 and AIM-XLI1 gauges, use the
equation P=10(7/8 V - 10.75) where P is the pressure in mbar, and V is the measured voltage.
If necessary, adjust the pressure reading to compensate for the type of residual gas in your vacuum system
(refer to Section 1.3).
WARNING
Do not use the AIM Gauge to measure the pressure of explosive or flammable gases or mixtures.
WARNING
Never operate the AIM Gauge when it is disconnected from the vacuum system or when there are
explosive or flammable gases in the surrounding atmosphere of the vacuum system. High voltages
(up to 3 kV) are generated inside the body tube of the AIM Gauge; these could cause injury to
people or could be a source of ignition.
WARNING
The AIM Gauge incorporates magnets. Keep away from heart pacemakers, computers, credit cards
and any other magnetically sensitive devices.

D146-71-880 Issue E
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Operation
4.4 Set-point
Note: The set-point is not used if you connect the AIM Gauge to an Edwards Controller.
To adjust the voltage at which the set-point output signal goes on, turn the set-point potentiometer, which is
accessible through an access hole in the end cap of the gauge: see Figure 1. Turn the potentiometer clockwise to
increase the voltage and turn it anticlockwise to decrease the voltage. Refer to Section 4.3 to determine the
operating voltage which corresponds to a given pressure.
The AIM Gauge has an error monitoring facility, which ensures that the set-point output signal is off:
When the gauge is switched off (that is, not enabled)
For 0.5 seconds immediately after the AIM Gauge is switched on
When the pressure output signal is out of range, perhaps because the gauge has failed to strike (ignite)
If required you can adjust the potentiometer so that the set-point operating voltage is < 1.8 V (that is, turn the
potentiometer fully anticlockwise). This ensures that the set-point output signal is permanently off.
If required, you can use the set-point output signal to indicate when the Gauge is operating correctly; adjust the
potentiometer so that the set-point operating voltage is 10 V (that is, turn the potentiometer fully clockwise). If
the gauge is operating normally, the set-point output signal will then be switched on.
Note: If you adjust the set-point operating voltage to > 9.5 V the hysteresis voltage will be > 10 V and the set-
point output signal may not switch off when the pressure rises; if so, the set-point output signal will only
go off when the gauge is switched off (that is, disabled).
Table 2 - Pressure and voltage characteristics for nitrogen and dry air
Pressure (mbar) Output voltage Pressure (torr)
1.0 x 10-8 2.00 7.5 x 10-9
2.4 x 10-8 2.50 1.8 x 10-8
5.8 x 10-8 3.00 4.4 x 10-8
8.1 x 10-8 3.20 6.1 x 10-8
1.1 x 10-7 3.40 8.3 x 10-8
1.5 x 10-7 3.60 1.1 x 10-7
2.1 x 10-7 3.80 1.6 x 10-7
2.9 x 10-7 4.00 2.2 x 10-7
4.0 x 10-7 4.20 3.0 x 10-7
5.4 x 10-7 4.40 4.1 x 10-7
7.3 x 10-7 4.60 5.5 x 10-7
9.8 x 10-7 4.80 7.4 x 10-7
1.3 x 10-6 5.00 9.8 x 10-7
1.7 x 10-6 5.20 1.3 x 10-6
2.2 x 10-6 5.40 1.7 x 10-6
2.8 x 10-6 5.60 2.1 x 10-6
3.6 x 10-6 5.80 2.7 x 10-6
4.5 x 10-6 6.00 3.4 x 10-6
5.6 x 10-6 6.20 4.2 x 10-6
6.9 x 10-6 6.40 5.2 x 10-6
8.4 x 10-6 6.60 6.3 x 10-6

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Operation
D146-71-880 Issue E
1.0 x 10-5 6.80 7.5 x 10-6
1.2 x 10-5 7.00 9.0 x 10-6
1.4 x 10-5 7.20 1.1 x 10-5
1.7 x 10-5 7.40 1.3 x 10-5
2.0 x 10-5 7.60 1.5 x 10-5
2.4 x 10-5 7.80 1.8 x 10-5
2.9 x 10-5 8.00 2.2 x 10-5
3.5 x 10-5 8.20 2.6 x 10-5
4.3 x 10-5 8.40 3.2 x 10-5
5.7 x 10-5 8.60 4.3 x 10-5
7.9 x 10-5 8.80 5.9 x 10-5
1.2 x 10-4 9.00 9.0 x 10-5
1.9 x 10-4 9.20 1.4 x 10-4
3.3 x 10-4 9.40 2.5 x 10-4
6.7 x 10-4 9.60 5.0 x 10-4
1.7 x 10-3 9.80 1.3 x 10-3
3.6 x 10-3 9.90 2.7 x 10-3
1.0 x 10-2 10.00 7.5 x 10-3
Table 2 - Pressure and voltage characteristics for nitrogen and dry air (continued)
Pressure (mbar) Output voltage Pressure (torr)

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Maintenance
D146-71-880 Issue E
5Maintenance
5.1 Introduction
The internal components of the AIM Gauge are shown in Figure 4. The AIM Gauge is designed so that you can clean
these components, or use the spares listed in Section 7 to replace these components. Refer to the following sections
for details of the maintenance procedures which you should do when necessary.
5.2 Replace the body tube
Refer to Figure 1 and use the following procedures to replace the body tube.
5.2.1 Remove the AIM gauge from the vacuum system
1. Switch off the AIM Gauge electrical supply and ensure that the vacuum system is at atmospheric pressure.
2. Disconnect the cable connector plug (5) from the AIM Gauge and remove the AIM Gauge from the vacuum
system.
5.2.2 Fit the new body tube
1. Hold the magnet housing (4) and turn the body tube (3) anticlockwise (when viewed from the vacuum flange) to
unlock the bayonet fitting. Remove the body tube from the magnet housing.
2. Slide the new body tube into the magnet housing (4).
3. Hold the magnet housing (4) and turn the body tube (3) clockwise (when viewed from the vacuum flange) to lock
the bayonet fitting.
5.2.3 Refit the AIM gauge to the vacuum system
Refit the AIM Gauge to the vacuum system as described in Section 3.2 and refit the cable connector plug to the socket
on the AIM Gauge (7).
WARNING
Do not disconnect the electronics and magnet housing from the body tube when the body tube is
connected to the vacuum system. If there is a plasma discharge in the vacuum system near the
body tube, the body tube can become electrically charged.
WARNING
Disconnect the AIM Gauge before you remove the AIM Gauge from the vacuum system. High
voltages are generated inside the AIM Gauge.

D146-71-880 Issue E
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Maintenance
5.3 Replace the electrode assembly
CAUTION
Internal anode assembly includes a sharp-edged component. Care should be taken when handling this item.
Refer to Figure 4 in the following procedure.
1. Remove the AIM Gauge from the vacuum system as described in Section 5.2.1.
2. Remove the body tube from the AIM Gauge as described in Step 1 of Section 5.2.2.
3. Fit the flat spanner supplied in the electrode assembly kit (refer to Section 7) to the two lugs in the end of the
collar (1), then turn the collar anticlockwise to unscrew the collar from the body tube (4) and remove the anode
assembly (2) and the O-ring (3).
4. Use circlip pliers to remove the circlip (8) from the vacuum flange end of the body tube, then remove the outer
cathode plate (7), cathode tube (6) and the inner cathode plate (5).
5. Fit the new inner cathode plate (5) into the body tube (4) ensuring the end with reduced diameter is furthest
from the vacuum flange. Then fit both new cathode tubes (6). If this has been done correctly the second
cathode tube will now be protruding about 2 mm beyond the end of the vacuum flange. Hold the outer tube so
that the inner cathode plate is held in place, invert the assembly, and rest the outer cathode tube on the bench.
6. Fit the new O-ring (3) and anode assembly (2) into the body tube.
7. Refit the collar (1) to the body tube. Locate the flat spanner on the two lugs on the collar and turn the collar
clockwise until it is fully secured in the body tube.
8. Hold the outer tube so that the inner cathode plate is held in place, and re-invert the assembly so that the
14-point striker on the anode can be seen. Remove and discard the outer cathode tube.
9. Now use the 0.5 mm diameter wire supplied to check that the minimum gap between the striker and the inner
cathode plate is at least 0.5 mm. This means ensuring the wire is able to pass between the striker and cathode
plate all the way round. If not, use a single (gloved) finger on the top of the anode to gently bend it in the
appropriate direction. Repeat the test and gentle bending if necessary until the striker-cathode plate gap
is 0.5 mm.
10.Fit the new outer cathode plate (7) and secure with the circlip (8). Ensure both the circlip centre and ends are
pushed tight towards the inner cathode plate.
11.Refit the tube assembly to the magnet housing as described in Step 2 and 3of Section 5.2.2. Refit the vacuum
gauge to the vacuum system as described in Section 5.2.3.
5.4 Replace the electronics and magnet housing
The magnet housing and end-cap contain the AIM Gauge control electronics. Replace the complete unit as described
below.
1. Remove the AIM Gauge from the vacuum system.
2. Remove the body tube from the AIM Gauge.
3. Dispose of the old magnet housing and end cap (refer to Section 6).
4. Fit the body tube to the new magnet housing and end-cap. Refit the AIM Gauge to the vacuum system.

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Maintenance
D146-71-880 Issue E
5.5 Clean the internal components
Refer to Figure 4 in the following procedure.
1. Remove the internal components from the magnet housing.
2. Degrease the cathode plate (5), cathode tube (6), body tube (4) and anode assembly (2) in a suitable degreasing
agent.
3. Thoroughly soak the components in a suitable laboratory detergent.
4. Rinse the components in clean water to remove the detergent.
5. Rinse the components in alcohol to remove all of the water, then thoroughly dry the components.
6. Inspect the anode assembly and cathode plates to ensure they have no tiny hairs attached.
7. Refit the components in the magnet housing.
Figure 4 - Exploded view of the AIM gauge tube assembly
5.6 Fault finding
If the AIM Gauge does not operate correctly, ensure that the electrical connections are correct (refer to Section 3)
and ensure that your electrical supply is suitable for the AIM Gauge (refer to Section 2).
1. Collar
2. Anode assembly
3. O-ring
4. Body tube
5. Inner cathode plate
6. Cathode tube
7. Outer cathode plate
8. Circlip

D146-71-880 Issue E
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