Background compensation, Sensitivity, Auto range – INFICON Sensistor ISH2000 Hydrogen Leak Detector User Manual

Page 28: Direct sensitivity adjustment, Audio threshold, Reject indication

Hydrogen leak detector Sensistor ISH2000

Operating Manual

OM-Sensistor ISH2000-EN-201304

over the condenser, the signal will increase as the probe approaches the leak. If the
signal goes off the scale, simply reduce the sensitivity setting to bring the signal
within the scale. By working with the sensitivity setting in this way, you will be able
to locate multiple leaks that are in close proximity to each other.

Do not expose the probe to more gas than is necessary, because it will slowly
saturate with time. It is good practice to detect a leak, locate it, and immediately
remove the probe to avoid saturation. The probe is not damaged by the exposure
but it will recover more slowly. After excessive exposure it will be less sensitive for a
short period of time.

Background Compensation

There is always some hydrogen gas in the background. In fresh air this is as low as
0.5 ppm (parts per million).

Sensistor ISH2000 actively adjusts itself to the background. This is done
automatically at start-up and thereafter, it slowly adapts itself to slow variations in
the background concentration. By adjusting slowly (minutes) it avoids mistaking an
actual leak for an increased background and vice versa. Therefore, a sudden rise in
background concentration will be detected. However, if the concentration remains
constant it will be gradually canceled out over a period of several minutes.

For example, if the background concentration for some reason should suddenly rise
to 10 ppm H

, then the detector will give a corresponding signal which will very

slowly decline to zero. If you thereafter expose the probe to a leak which gives rise
to another 10 ppm H

, then the detector will give essentially the same signal as if

there were no background concentration.

Sensitivity

Sensitivity

of audio signal and signal bar in

Locating Mode

Note:

This does not affect the

Measuring Mode

Auto Range

Set this parameter to

for auto ranging of sensitivity in

Locating Mode

. Sensitivity

will decrease two steps if the signal reaches full scale. Sensitivity is restored to
selected

Sensitivity

when signal returns to zero.

Direct Sensitivity Adjustment

Setting this parameter to

OFF

will remove the sensitivity adjustment from the

Locating Mode

display. Sensitivity can still be adjusted in the

Sensitivity Settings

after entering password (if set).

Note:

The sensitivity setting only affects the

Locating Mode and Combined Mode

Audio Threshold

Makes it possible to mute the sound to a set level in Locating Mode. The level is in %
of full Locating bar.

Reject Indication

Makes it possible to show the indication Reject in Locating Mode.