Instrutech Hornet CCM502 User manual

p/n 002552-100
InstruTech®
Cold Cathode Ionization Vacuum Gauge
CCM502 Module
The Hornet™
User Manual
InstruTech
1475 S. Fordham St.
Longmont, CO 80503
USA
Phone: [phone]
Fax: [phone]
E-mail [email protected]
www.instrutechinc.com

Instruction Manual CCM502 Hornet
InstruTech Page 1
Important User Information There are operational characteristic differences between solid state equipment and
electromechanical equipment. Because of these differences, and because there are a variety of uses for solid state equipment, all
persons that apply this equipment must take every precaution and satisfy themselves that the intended application of this equipment is
safe and used in an acceptable manner.
In no event will InstruTech be responsible or liable for indirect or consequential damages that result from the use or application of this
equipment.
Any examples or diagrams included in this manual are provided solely for illustrative purposes. Because of the many variables and
requirements imposed on any particular installation, InstruTech cannot assume responsibility or liability for any actual use based on the
examples and diagrams.
No patent liability is assumed by InstruTech with respect to use of information circuits, equipment, or software described in this manual.
Throughout this manual we use notes, notices and apply internationally recognized symbols and safety messages to make you aware of
safety considerations.
Identifies information about practices or circumstances that can cause electrical or physical hazards which, if precautions are not taken,
could result in death or serious injury, property damage, or economic loss.
Identifies information about practices or circumstances that can cause electrical or physical hazards which, if precautions are not taken,
could result in minor or moderate injury, property damage, or economic loss.
Identifies information that is critical for successful application and understanding of the product.
Labels may be located on or inside the device to alert people that dangerous voltages may be present.
CAUTION
CccWARNING
WARNING
NOTICE
SHOCK HAZARD
CccWARNING
WARNING

p/n 002552-100
Copyright © 2016 by InstruTech
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying and recording, or by any information storage or retrieval system, except as may be expressly permitted in
writing by InstruTech.
Printed in the United States of America
Conflat® is a registered trademark of Varian, Inc. / Agilent Technologies, Lexington, MA

Instruction Manual CCM502 Hornet
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Table of Contents
1 Introduction / General Information....................................................................................................................3
1.1 Description .................................................................................................................................................3
1.2 Specifications .............................................................................................................................................3
1.3 Dimensions.................................................................................................................................................4
1.4 Part Numbers .............................................................................................................................................5
1.5 Options & Accessories................................................................................................................................5
2 Important Safety Information.............................................................................................................................6
2.1 Safety Precautions - General......................................................................................................................6
2.2 Safety Precautions - Service and operation ...............................................................................................7
2.3 Electrical Conditions...................................................................................................................................8
2.3.1 Proper Equipment Grounding............................................................................................................8
2.3.2 Electrical Interface and Control..........................................................................................................8
2.4 Overpressure and use with hazardous gases.............................................................................................8
2.5 Gas Dependency.........................................................................................................................................9
3 Installation ........................................................................................................................................................10
3.1 Mechanical Installation............................................................................................................................10
3.2 Electrical Installation................................................................................................................................11
3.2.1 Grounding.........................................................................................................................................11
3.2.2 Connector.........................................................................................................................................12
3.2.3 Connectors pin-out...........................................................................................................................12
4 Setup and Operation.........................................................................................................................................13
4.1 Applying power ........................................................................................................................................13
4.2 Overpressure shut down..........................................................................................................................13
4.3 Activating the sensor................................................................................................................................13
4.4 Status Indication.......................................................................................................................................14
4.5 Sensor activation delay ............................................................................................................................14
5 Using the gauge with different gases ...............................................................................................................15

Instruction Manual CCM502 Hornet
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6 Analog Output...................................................................................................................................................16
7 Service...............................................................................................................................................................17
7.1 Calibration................................................................................................................................................17
7.2 Maintenance ............................................................................................................................................17
7.3 Contamination..........................................................................................................................................17
7.4 Removing the gauge from service............................................................................................................18
7.4.1 Inspecting the sensor .......................................................................................................................19
7.4.2 Replacing the ionization chamber and sensor activation aid ..........................................................20
7.4.3 Replacing the measuring chamber...................................................................................................22
7.5 Troubleshooting.......................................................................................................................................23
8 Factory Service and Support.............................................................................................................................24
9 Warranty...........................................................................................................................................................24

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1 Introduction / General Information
1.1 Description
A cold cathode ionization gauge measures vacuum pressure by first ionizing gas molecules inside the vacuum
gauge and then measuring the resulting ion current. A large potential between the sensor anode and cathode
will cause ionization to occur. The amount of ion current generated from the ionized gas is proportional to the
pressure in the vacuum system and is dependent on the type of gas used. As the pressure inside the vacuum
system drops, the measured ion current drops. Two ion current collector options are available. The low current
collector option is recommended for use in heavy gases such as argon to prevent self-sputtering while the high
current version is recommended for gases such as N2/air, etc.
The InstruTech® CCM502 Hornet™ module provides the basic signal conditioning required to turn a cold cathode
vacuum gauge into a complete measuring instrument. The module provides a log-linear analog output for the
measured pressure and requires a digital input to activate the sensor. Additionally, the instrument provides a
sensor on/off status using an open collector transistor output as well as a status LED. The measurement range
for the CCM502 cold cathode ionization gauge is 7.6 x 10-10 to 7.6 x 10-3 Torr.
1.2 Specifications
measurement range
7.6 x 10-10 to 7.6 x 10-3 Torr / 1 x 10-9 to 1 x 10-2 mbar / 1 x 10-7 to 1 Pa
accuracy - N2 (typical)
7.6 x 10-9 to 7.6 x 10-3 Torr: ± 30% of reading
repeatability - (typical)
7.6 x 10-9 to 7.6 x 10-3 Torr: ± 5% of reading
materials exposed to gases
anode: molybdenum others: Ni alloy, AI2O3, stainless steel, glass
internal gauge volume
1.391 in3 (22.8 cm3)
admissible pressure
145 psi, 10 bar absolute (limited to inert gases < 50 oC)
temperature
operating: + 5 to + 55 oCstorage: -40 to + 70 oC
humidity (30 days a year)
7.6×10-8 … 7.6 ×10-3 Torr
0 to 95% relative humidity, non-condensing
7.6×10-9 … 7.6 ×10-3 Torr
0 to 70% relative humidity, non-condensing
bakeout temperature (at flange)
150 oC(sensor only - electronics removed)
weight
0.61 lb. (0.28 kg) with NW25 KF flange
housing (electronics)
aluminum extrusion
use
indoor
mounting orientation
any
input signal
sensor enable (anode voltage turned on) is set by continuity to ground
analog output
log-linear 0 to 8 Vdc, 1 V/decade
output impedance
2 × 4.7 , short-circuit proof
load impedance
≥10 k, short-circuit proof
error signal
analog output switches to ≥ 10 V
response time
p = 7.6 X 10-9 Torr
~1 sec
p > 7.6 X 10-7 Torr
<100 msec
sensor status output
sensor on/off status is determined by open collector transistor (ground emitter) rated at 30 V
max. VCE, 100 mA max. IC. Transistor off = Sensor off, Transistor on = Sensor on
sensor status indication on gauge
sensor ON/OFF status indication via LED

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input power (1)
14.5 to 30 Vdc, 2 W protected against power reversal and transient over-voltages
(Minimum voltage of the power supply unit must be increased proportionally to the length of the cable)
fuse required
≤ 1AT
supply voltage ripple
<1 Vp-p
high voltage in measuring chamber
operating voltage (anode): <3.3 KV
sensor activation voltage (anode): <4.5 KV
current in measuring chamber
low current collector version: ≤ 100 µA
high current collector version: ≤ 500 µA
connector
9-pin D-sub male
altitude
19,685 ft. (6,000 m) max
CE compliance
EMC (EN61000-6-2, EN61000-6-3, EN61010-1, EN61326-1)
environmental
RoHS compliant
(1) WARNING! The gauge may only be connected to power supplies, instruments, or control devices that conform to the
requirements of a grounded protective extra-low voltage (SELV) and limited power source (LPS), Class 2. The connection to the gauge has
to be fused.
1.3 Dimensions
in. (mm)
Fitting dimension A
NW25KF 0.59 in. (15 mm)
NW40KF 0.67 in. (17 mm)
2 3/4 in. Conflat® 0.91 in. (23 mm

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1.4 Part Numbers
CCM502 Part Number Spare Parts / Accessories Part Numbers
Sensor Version
S= Standard
CCM502 S # # A
CCM502 Spare Sensor, NW25KF
CCM502 Spare Sensor, NW40KF
CCM502 Spare Sensor, 2 3/4 in. CF / NW40CF Conflat
Spare Ionization Chamber
Sensor (anode) activation aid (set of 10 pcs)
Tool set for removing/installing sensor activation aid
Centering ring with fine filter, NW25KF
CC5SC
CC5SD
CC5SF
002588
002587
002586
002585
Collector
H= High Current
L = Low Current
Fittings / Flanges
C= NW25KF
D= NW40KF
F= 2 3/4 in. CF / NW40CF Conflat®
Electrical Connector
A= 9-pin D-sub male
Example: CCM502SHDA (CCM502 with standard sensor, high current collector, NW40KF fitting, 9-pin D-Sub connector)
1.5 Options & Accessories
PS501-A
‘
Description: Power supply
Compatibility: Powers the CCM502 Hornet™
vacuum gauge module
Power Input: 100 - 240 Vac
Power Plug: North American 115 Vac plug
Output: 24 Vdc @ 750 mA (18 W)
Connector: 9-pin D-sub female to mate with and power the
CCM502 module
Cable length: 6 ft. (2 m)
Note: 9-pin D-sub connector backshell can be opened to
enable connections to signals and relays

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2 Important Safety Information
InstruTech has designed and tested this product to provide safe and reliable service, provided it is installed and
operated within the strict safety guidelines provided in this manual.Please read and follow all warnings and
instructions.
To avoid serious injury or death, follow the safety information in this document. Failure to comply with these
safety procedures could result in serious bodily harm, including death, and or property damage.
Failure to comply with these warnings violates the safety standards of installation and intended use of this
instrument. InstruTech disclaims all liability for the customer’s failure to comply with these instructions.
Although every attempt has been made to consider most possible installations, InstruTech cannot anticipate
every contingency that arises from various installations, operation, or maintenance of the module. If you have
any questions about the safe installation and use of this product, please contact InstruTech.
2.1 Safety Precautions - General
Hazardous voltages are present with this product during normal operation. The product should never be
operated with the cover removed.
WARNING! Do not modify this product or substitute any parts without authorization of qualified
InstruTech service trained personnel. Return the product to an InstruTech qualified service and repair center to
ensure that all safety features are maintained. Do not use this product if unauthorized modifications have been
made.
WARNING! Source power must be removed from the product prior to performing any servicing.
WARNING! The gauge may only be connected to power supplies, instruments, or control devices that
conform to the requirements of a grounded protective extra-low voltage (SELV) and limited power source (LPS),
Class 2. The connection to the gauge has to be fused.
After servicing this product, ensure that all safety checks are made by a qualified service person. When
replacement parts are required, ensure that the parts are specified by InstruTech. Substitutions of non-
qualified parts may result in fire, electric shock or other hazards. Use of unauthorized parts or modifications
made to this product will void the warranty.
To reduce the risk of fire or electric shock, do not expose this product to rain or moisture. These products are
not waterproof and careful attention must be paid to not spill any type of liquid onto these products. Do not
use these products if they have been damaged. Immediately contact InstruTech to arrange return of the
product if it is damaged.
WARNING
WARNING
WARNING

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Due to the possibility of corrosion when used in certain environmental conditions, it is possible that the
product’s safety could be compromised over time. It is important that the product be periodically inspected for
sound electrical connections and equipment grounding. Do not use if the equipment grounding or electrical
insulation has been compromised.
2.2 Safety Precautions - Service and operation
Ensure that the vacuum port on which the CCM502 is mounted is electrically grounded.
Do not turn on the anode voltage and try to activate the sensor when pressure exceeds 7.60 x 10-3 Torr.
WARNING! The power supply used in the Cold Cathode Gauge Module (CCM502) is subject to high
voltages which could cause severe injury or death. In order to prevent electric shock and bodily harm, the user
should wait 1 minute after power is removed before touching the CCM502 power supply components.
WARNING! When the anode voltage is turned on and the sensor activated, 3,300 Vdc to 4,500 Vdc is
present at the internal power supply and other components. DO NOT operate the CCM502 with the CCM502
enclosure removed. Contact with exposed electrical circuits in the CCM502 could result in death or serious
injury.
Use an appropriate power source of 14.5 to 30 Vdc, 2 W minimum.
Turn off power to the unit before attempting to service the module.
Turn off power to the unit before detaching the electronics from the sensor for sensor replacement, sensor
cleaning or bake-out purposes.
Turn off power to the unit if a cable or plug is damaged or the product is not operating normally according to
this instruction manual. Contact qualified InstruTech service personnel for any service or troubleshooting
condition that may not be covered by this instruction manual.
Do not use if the unit has been dropped or the enclosure has been damaged. Contact InstruTech for return
authorization and instructions for returning the product to InstruTech for evaluation.
The most common cause of all vacuum gauge failures is contamination of the sensor. Noisy, abnormally low, or
erratic readings and total gauge failure are possible indications of gauge contamination.

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2.3 Electrical Conditions
WARNING! When high voltage is present in any vacuum system, a life threatening electrical shock hazard
may exist unless all exposed electrical conductors are maintained at earth ground potential. This applies to all
products that come in contact with the gas contained in vacuum chambers. An electrical discharge within a
gaseous environment may couple dangerous high voltage directly to any ungrounded conductor of electricity. A
person could be seriously injured or killed by coming in contact with an exposed, ungrounded electrical
conductor at high voltage potential. This condition applies to all products that may come in contact with the gas
inside the vacuum chamber (vacuum/pressure containment vessel).
2.3.1 Proper Equipment Grounding
WARNING! Hazardous voltages that could seriously injure or cause death are present in many vacuum
processes. Verify that the vacuum connection port on which the ion gauge is mounted is electrically grounded.
Consult a qualified Electrician if you are in doubt about your equipment grounding. Proper grounding of your
equipment is essential for safety as well as intended operation of the equipment.
The CCM502 must be electrically connected to the grounded vacuum chamber. The connection must conform
to the requirements of a protective connection according to EN 61010:
➔VCR® connections fulfill this requirement.
➔For gauges with a KF connection, use a conductive metallic clamping ring.
WARNING! In order to protect personnel from electric shock and bodily harm, shield all conductors
which are subject to potential high voltage electrical discharges in or around the vacuum system.
2.3.2 Electrical Interface and Control
It is the user’s responsibility to ensure that the electrical signals from this product and any connections made to
external devices, for example, relays and solenoids, are used in a safe manner. Always double check the system
set-up before using any signals to automate your process. Perform a hazardous operation analysis of your
system design and ensure safeguards and personnel safety measures are taken to prevent injury and property
damage.
2.4 Overpressure and use with hazardous gases
WARNING! Install suitable protective devices that will limit the level of pressure inside your vacuum
chamber to less than what the vacuum chamber system components are capable of withstanding. For example,
a quick-connect, O-ring compression fitting may forcibly release a mounted device from the vacuum chamber
fitting with only a few psi over local uncorrected barometric (atmospheric) pressure.
In cases where an equipment failure could cause a hazardous condition, always implement fail-safe system
operation. For example, use a pressure relief device in an automatic backfill operation where a malfunction
could result in high internal pressures if the pressure relief device was not installed on the chamber.

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WARNING! Overpressure in the vacuum system > 14.5 psia (1 bar)
Injury caused by released parts and harm caused by escaping process gases can result if clamps are opened
while the vacuum system is pressurized. Do not open any clamps while the vacuum system is pressurized. Use
the type of clamps which are suited to overpressure.
WARNING! Overpressure in the vacuum system > 29 psia (2.5 bar)
KF connections with elastomer seals (O-rings) cannot withstand such pressures. Process media can thus leak
and possibly damage your health. Use O-rings provided with an outer centering ring.
CAUTION! If the internal pressure of a vacuum measuring device is allowed to increase above local
uncorrected barometric pressure (atmospheric pressure side), vacuum fittings may release and possible
overpressure conditions may cause leaks that would allow the gas inside the tube to release into the
atmosphere of the surrounding environment. Toxic, pyrophoric and flammable gases are examples of
hazardous gases that if allowed to leak out of the vacuum/pressure containment vessel into the atmospheric
environment, could cause bodily injury and possible damage to equipment. Never expose the vacuum
measuring device internal volume to pressure above local atmospheric pressure when using hazardous gases.
2.5 Gas Dependency
WARNING! The measurement value is gas dependent. The pressure reading applies to dry air, O2, CO and
N2. For other gases, the measurements have to be corrected. Refer to section 5 titled “Using the gauge with
different gases” for a more details.

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3 Installation
3.1 Mechanical Installation
CAUTION! Dirt and damage can impair the function of the vacuum component. Take appropriate
measures to ensure cleanliness and prevent damage. Touching the product or parts with bare hands increases
the desorption rate. Always use clean, lint free gloves as well as clean tools when working with this product.
Mount the CCM502 as close as possible to the pressure you want to measure. Long or restricted, small diameter
tubing will create a pressure difference between your process chamber and the gauge. This may cause a delay
in response to pressure changes. Mounting the CCM502 too close to a gas source inlet may also cause
measurement and control instability.
The CCM502 can be mounted in any orientation, however, if possible, mount the gauge with port down to help
minimize the effect of any particles or condensation collecting in the gauge.
For electrical safety purposes the housing of the gauge must be grounded to the vacuum chamber. When using
KF flanges, metal clamps must be used to ensure proper grounding. Do not attempt to modify your flange in
order to use non-metallic-type flange clamps.
Use all metal vacuum fittings with metal seals when operating pressures are expected to be below
1.00 x 10-7 Torr (1.33 x 10-7 mbar, 1.33 x 10-5 Pa).
For potentially contaminating applications and to protect the measurement system against contamination,
installation of the optional seal with centering ring and filter is recommended. See section 1.4 for accessories
part numbers.
Remove the protective lid and install the product to the vacuum system following manufacturer’s
recommendations for different flanges and fittings. Keep the protective lid for future maintenance.
or
Protective lid
Seal with centering
ring and filter
Clamp
Seal with centering ring

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When making a CF flange connection, it may be advantageous to temporarily remove the electronics unit as
shown below.
Hexagon socket AF 2
Protective lid
WARNING! Helium may cause electric arcing with detrimental effects on the electronics of the product.
Before performing any leak tests disconnect power and remove the electronics unit.
3.2 Electrical Installation
3.2.1 Grounding
WARNING! Be sure the vacuum gauge and the rest of your vacuum system are properly grounded for
safety as well as intended operation of the equipment. When using KF flanges, metal clamps must be used to
ensure proper grounding.
WARNING! The gauge may only be connected to power supplies, instruments or control devices that
conform to the requirements of a grounded protective extra-low voltage (SELV) and limited power source (LPS),
Class 2. The connection to the gauge has to be fused.
Ground loops, differences of potential, or EMC problems may affect the measurement signal. For optimum
signal quality, please do observe the following:
•Use an overall metal braided shielded cable. The connector must have a metal case.
•Connect the supply common with protective ground directly at the power.
•Use differential measurement input (signal common and supply common conducted separately).
•Potential difference between supply common and housing ≤16 V (overvoltage protection).

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3.2.2 Connector
Good, recommended practice is to remove power from any cable prior to connecting or disconnecting it.
1) The CCM502 is provided with one 9-pin D-sub male connector used for the I/O interface. Fabricate a cable to
connect to the vacuum gauge as shown below:
3.2.3 Connectors pin-out
9-pin D-sub (DE-9P) male connector (used for analog output and digital I/O)
PIN NUMBER
PIN DESCRIPTION
1
Sensor enable (HV On/Off) - Low active digital input
The high voltage to anode is turned on and cold cathode sensor is activated by applying a continuous
ground. The sensor is turned off by removing the ground. See section 4.3 for other methods of
activating the sensor.
2
Power common GND
3
Analog output (Log-Linear 0 to 8 Vdc, 1 V/decade)
4
Power Input (14.5 to 30 Vdc, 2 W) protected against power reversal and transient over-voltages
5
Not assigned
6
Do not connect
7
Analog output common (Do not use for sensor enable ground)
8
Not assigned
9
Sensor on/off status is determined by open collector transistor (ground emitter) rated at 30 V max. VCE
, 100 mA max. IC. Transistor off = Sensor off, Transistor on = Sensor on
Wiring Diagram
* Applying continuous ground activates the cold cathode sensor.

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4 Setup and Operation
4.1 Applying power
Connect power to the CCM502 using the designated pins 4 and 2 of the 9-pin D-sub connector. Alternatively,
you can power the device by connecting InstruTech’s PS501-A power supply to the connector. Read this user
manual in its entirety before activating the sensor. Refer to section 4.3 titled “Activating the sensor” for further
details.
4.2 Overpressure shut down
The user must turn off the high voltage to sensor before pressure rises above 7.60 x 10-3 Torr, otherwise the
signal output will be erroneous with the sensor turned on above 7.60 x 10-3 Torr.
4.3 Activating the sensor
Before you turn on the anode high voltage and activate the sensor, make sure you understand all instructions
and information provided in this manual. You can activate the sensor by one of the following methods:
1) Digital Input - See section 3.2.3 Pin 1 (low active)
2) Using a Convection gauge relay to activate the cold cathode sensor
Because the useful operating range of the InstruTech’s cold cathode CCM502 is from 7.60 x 10-10 Torr to
7.6 x 10-3 Torr, another vacuum gauge capable of measuring pressures above 7.60 x 10-3 Torr should be used to
determine when to turn on the high voltage to anode voltage and activate the sensor. This can be implemented
by using signals from another gauge such as an InstruTech convection enhanced Pirani (CG) gauge. For example,
you may use an InstruTech CVM211 Stinger™ or the CVM201 Super Bee™ convection gauge to activate or
deactivate the cold cathode sensor. The setpoint relay from the CVM211 or CVM201 can be physically wired to
the cold cathode connector (see typical connection scheme below). The relays in the CVM211 or CVM201 can
be configured to energize at the desired pressure at which the cold cathode sensor will be activated. The cold
cathode sensor is activated (operational) by applying a continuous ground thru the relay connections of the
CVM211 or CVM201. The sensor is deactivated when relay is de energized discontinuing the application of
ground.
CCM502 Hornet
Connector DE-9P
CAUTION! Activating the sensor at pressures higher than 7.60 x 10-3 Torr may result in contamination
buildup and incorrect pressure measurement.

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4.4 Status Indication
DIA
ADJ
CAL
HV-ST
ST
E
C
A
024
6
8
Supply voltage
Error
High voltage
cold cathode
For factory
setting only
Calibration
value
LED
Condition
<ST>
<HV-ST>
off
off
No supply voltage
lit solid green
off
Supply voltage = ok,
no high voltage in the measuring
chamber
lit solid green
blinking
green
Supply voltage = ok,
pressure in the cold cathode range,
cold cathode has not ignited
lit solid green
lit solid
green
Cold cathode has ignited
blinking red
off
EEPROM error
4.5 Sensor activation delay
An ignition delay occurs when cold cathode gauges are switched on. The delay time increases at low pressures
and is typically:
7.60 ×10-6 …7.60 × 10-3 Torr
< 1 second
7.6 × 10-8 …7.6 × 10-6 Torr
< 20 seconds
3.75 × 10-9 …7.6 × 10-8 Torr
< 2 minutes
< 3.75 × 10-9 Torr
< 20 minutes

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5 Using the gauge with different gases
The measurement value is gas dependent. The pressure reading applies to dry air, O2, CO and N2. For other
gases, the measurements have to be corrected.
Indicated pressure (gauge calibrated for air)
4
2
10–3
8
6
4
2
10–4
8
6
4
2
10–5
8
6
4
2
10–6
8
6
4
2
10–7
10–7 2 4 6 10–6 2 4 6 10–5 2 4 6 10–4 2 4 6 10–3 2 4 6 10–2
Xe Kr
Air
O2
CO
N2H2Ne He
peff [Torr]
p [Torr]
Ar
Indication range below 1.0 x 10-5 Torr
In the range below 10-5 the pressure indication is linear. For gases other than air, the pressure can be
determined by means of the following conversion formula:
peff = K × indicated pressure
where:
Gas type
K
Air (N2, O2,CO)
1.0
Xe
0.4
Kr
0.5
Ar
0.8
H2
2.4
Ne
4.1
He
5.9
These conversion factors are average values.
Example: If the gas in use is argon (Ar) and the CCM502 indicates a measured pressure of 7.6 x 10-6 Torr,
peff = 0.8 X 7.60 X 10-6 = 6 X 10-6 Torr true pressure of argon gas
A mixture of gases and vapors is often involved. In this case, accurate determination is only possible with a
partial pressure measurement instrument, e.g. a quadrupole mass spectrometer.

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6 Analog Output
The CCM502 provides a 0 to 8 Vdc, 1 V/decade log-linear signal proportional to pressure.
A) The log-linear output signal and pressure are related by the
following formulas when units of measurement is in Torr and mbar:
P= 10(volts –10) V= log10(P) + 10
Where P is the pressure in Torr or mbar, and V is the output signal
in volts.
B) The log-linear output signal and pressure are related by the
following formulas when units of measurement is in pascals:
P= 10(volts - 8) V= log10(P) + 8
Where P is the pressure in pascals, and V is the output signal in
volts.
The output voltage is +10 Vdc under the following conditions:
1) The sensor is turned off.
2) The gauge has not stabilized and no valid pressure signal is
detected.
Log-Linear Analog Output
Pressure (Torr)
Voltage
1.00E-09
1.00
1.00E-08
2.00
1.00E-07
3.00
1.00E-06
4.00
1.00E-05
5.00
1.00E-04
6.00
1.00E-03
7.00
7.60E-03
7.88
Sensor is off
10.00
The following chart shows the graphical results of table and formulas above.
Pressure is plotted on the X-axis with a log scale; the output signal is plotted on the Y-axis on a linear scale.
+ 10 VDC
See the conditions
described above
which cause the
output to switch
to + 10VDC.

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7 Service
7.1 Calibration
The gauge is factory-calibrated and the pressure reading applies to dry air, O2, CO and N2. For other gases, the
readings have to be corrected as described in section 5.
7.2 Maintenance
In general, under clean operating conditions, maintenance is not required for the CCM502. In case of a defect :
•Only replace the ionization chamber and ignition aid, or
•Replace the measuring chamber (spare sensor)
InstruTech assumes no liability and the warranty becomes null and void if any repair work other than replacing
the sensor activation (ignition) aid, measuring or ionization chambers is carried out by the end-user or third
parties.
7.3 Contamination
The most common cause of all vacuum gauge failures is contamination of the sensor. Noisy or erratic readings,
gauge failures due to contamination or wear and tear, as well as expendable parts (e.g. ionization chamber,
ignition aid) are not covered by the warranty.
Gauge contamination is influenced by the process media used as well as any existing or new contaminants and
their respective partial pressures. Continuous operation in the range of 7.6 x 10-5 Torr ... 7.6 x 10-3 Torr can
cause severe contamination as well as reduced up-time.
Contamination of the gauge generally causes a deviation of the measured values. In the low pressure range
(p < 7.6 × 10-4 Torr), the pressure indication is usually too low (as a consequence of the contamination of the
cold cathode system). In case of severe contamination, instabilities can occur (layers of the measuring chamber
peel off). Contamination due to isolating layers can even lead to a complete failure of the discharge.
Contamination can to a certain extent be reduced by:
•Geometric protection (e.g. screenings, elbows) against particles that spread rectilinearly
•Mounting the flange of the gauge at a place where the partial pressure of the pollutants is particularly low.
Special precautions are required for vapors deposited under plasma (of the cold cathode measuring system).
While vapors occur it may even be necessary to:
•Temporarily switch off the gauge.
•Temporarily seal off of the gauge from the vacuum chamber using a valve.
When using the gauge in gases containing contaminants, periodic replacement of ionization or measuring
chamber maybe required.