INFICON Sensistor ISH2000 Hydrogen Leak Detector - Manual (Page 8)

Sensistor ISH2000 Technical Reference Manual (TRM) EN- 8
A 400 Testing methods
To Detect leaks
If all you wish to do is to detect the presence of a leak, that is, find out whether
there is a leak or not, then use the Detection Mode (or use the detection bar in
Combined Mode). The definition of Leak/No Leak will then simply be "A leak is
a leak when it can be detected by the detector, set to a specific sensitivity".
To set up:
The operation in Detection Mode is not quantitative. The audio and visual sig-
nal will increase and decrease with the gas concentration. Therefore, there is no
actual calibration to be done, but rather a setting of the sensitivity to a desired
level.
A typical set-up procedure for Detection Mode is:
• Set up a reference leak which corresponds to the smallest leak you wish to
detect.
• Put the probe close to the reference leak and note approximately what reac-
tion you get (no reaction, small, medium, high, full scale) within the first few
seconds.
• Set the sensitivity. This can be done permanently under the menu Detection
Mode Settings or temporarily as a Direct Sensitivity Adjustment on the display
(unless you have set this function to OFF under the Detection Mode Settings
menu).
There is also an Auto ranging function which can be selected under the Detec-
tion Mode Settings menu.
Note: If the Detection Mode is used and the alarm function is required to be
activated at a particular calibrated level, then the unit must be calibrated in
accordance with the instructions, see "Calibrate the leak detector" on page 17.
The reason for this is that the alarm is based on the Analysis Mode when the
Detection Mode is displayed.
To Locate Leaks
Note: The Detection Mode (or use the detection bar in Combined Mode) is
used to locate leaks. This mode is semi-quantitative, that is, it gives an audio
and visual signal which increases as a leak is approached (a higher gas concen-
tration) and decreases as you move the probe away from the leak. It does not
display figures. In this mode of operation leaks can easily be detected using a
sensitivity which can be preset.
Leaks can be located very accurately, even when there are other leaks nearby. If,
for example, you are trying to locate a leak on a product and the product has a
major leak, then you will get an audio signal as soon as the probe is placed
close to the product.
When the probe is moved around and over the product, the signal will increase
as the probe approaches the leak. If the signal goes out of scale, simply reduce
the sensitivity setting to bring the signal within the scale. Working with the sen-
sitivity setting this way you will be able to locate multiple leaks that are in close
proximity to each other.
Note: Working inside a confined space such as, for example, a cabinet or a nar-
row passage on a combustion engine there is a risk that the background con-
centration accumulates to levels close to the upper detection limit of the
detector. In such case it will not be possible to locate leaks as easily as in open
spaces.
A 400