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Instruction Manual
CCM502 Hornet
7 Service
7.1 Calibration
The gauge is factory-calibrated and the pressure reading applies to dry air, O
, CO and N
. For other gases, the
2
2
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
-5
-3
their respective partial pressures. Continuous operation in the range of 7.6 x 10
Torr ... 7.6 x 10
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
-4
(p < 7.6 × 10
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.
InstruTech
Page 17
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