RKI Instruments GD-70D Series - Manual (Page 40)

4 Detection Mode 4-4. Other functions
GD-70D - 40 -
4-4. Other functions
<Suppression Function>
Some types of sensor used with the detector are influenced by environmental changes (temperature,
humidity, and other characteristics) or interference gases (interference characteristics) in no small measure,
which affects the reading.
Therefore, the reading might vary around zero even in a normal environment with no gas leakage.
This function obscures influences by environmental changes and interference gases around zero that have
no meaning for your management rules of gas alarm. This function is used to hide (suppress) the variation
of the reading under the setting value, indicating zero.
<<Example: SiH4 0 - 15 ppm rated range>>
0.5ppm
SIH4
Suppression Disabled
A variation around zero is displayed as the reading.
↓
0.0ppm
SIH4
Suppression Enabled
A variation under the standard setting value = 6% FS (0.9 ppm) is hidden with
zero. (Zero suppression)
NOTE
In the maintenance mode, this function is disabled and the variation of the reading under the setting value is
displayed.
When a sensor unit with the oxygen deficiency alarm (OSU 0 - 25 vol%) is equipped, the zero suppression
is shifted to AIR suppression automatically. That is, a small variation of the reading around 20.9 vol% is
displayed as 20.9 vol%.
CAUTION
• A reading under zero is suppressed with the 10% FS suppression.
• A reading that is 10% FS or more under zero is displayed as "-0.0", which prevents an accurate gas
detection and needs the zero adjustment.