INFICON Sensistor ISH2000 Hydrogen Leak Detector - Manual (Page 60)

Sensistor ISH2000 Technical Reference Manual (TRM) EN- 60
C 300
Note: If calibration fails you can still use the instrument. Last valid calibration
parameters will be used. You should, however, check that the instrument reacts
to the reference.
Reference Value
Your reference should have a concentration or flow equal to or slightly above
what you want to measure. See the examples below for specific recommenda-
tions.
Example for reference gas:
• Reject Level is set at 8 PPM
• For good accuracy, use a reference gas between 8-80 ppm hydrogen.
• 8 PPM hydrogen in synthetic air will give best results.
Example for reference leak
• Reject Level level is set at 2.0E-4 atm. cc/s
• For best accuracy reference leak within 2.0E-4 - 2.0E-3 atm cc/s.
• A reference leak calibrated to 2.0E-4 atm. cc/s will give best accuracy.
Reference Unit
The Reference Unit is set in the Calibration menu. Select PPM, cc/s, cc/min,
SCCM, g/a, oz/yr, mbarl/s, mm3/min, Pa m3/s or Custom. When you select Cus-
tom you can enter any unit as long as it contains a maximun of 12 characters.
Calibration can be performed with:
• a known hydrogen concentration
• a known flow leak
The following characters can be used: Upper and lower case Roman letters, the
numbers ь, Е, Д,Ц, е,д,ц,%,/,(,),and - (dash).
Note: The space (““) is not supported. The leak rate unit string will be cut short
at the first space found.
Calibration Time
The calibration time decides how long time the detector looks for a reference
signal before giving up. If the calibration is set to, for example, 6 seconds the
detector will record the maximum signal during 6 seconds after that the opera-
tor (or external hardware) orders a calibration.
It is very important that all delays in gas exposure as well as reaction time of
sensor are taken into consideration when setting the calibration time. Calibra-
tion will not be correct if the maximum signal comes after that the calibration
time has terminated.
High signal! Check
reference! Reference signal is abnor-
mally high. Check that reference gas
mix is not replaced with
tracer gas mix.
Check condition of refer-
ence.
Check that reference leak
connections has no leaks.
Message Explanation Remedy