RKI Instruments RM-5000 Series Indicator/Alarm Unit - Manual (Page 50)

6 Operations and Functions 6-4. Other functions
RM-5000 - 50 -
6-4. Other functions
<Suppression Function>
Some types of detector heads connected to the indicator/alarm unit 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 fluctuate around zero even in a normal state 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 fluctuation
of the reading under the setting value, indicating zero.
<<Example: CH4 0 – 100% LEL Specifications>>
5
%LEL
CH4
Suppression Disabled
A fluctuation around zero is displayed as the reading.
↓
0
%LEL
CH4
Suppression Enabled
A fluctuation under the setting value is hidden with zero.
(Zero suppression)
NOTE
• In the maintenance mode, this function is disabled and the fluctuation of the reading under the setting
value is displayed.
• When a sensor unit with the oxygen deficiency alarm (O2: 0 - 25 vol%) is equipped, the zero
suppression is shifted to AIR suppression (20.9 vol%) automatically. That is, a small variation of the
reading around 20.9 vol% is displayed as 20.9 vol%.
<Zero Follower Function>
Some types of detector heads connected to the indicator/alarm unit might have sensitivity variations after
being used for a long period.
This function corrects the fluctuation of the reading at the zero point (zero drift) among the sensitivity
variations over time by a program manipulation to stabilize the zero point.
Zero Follower Off Zero Follower On
* The zero drift of the sensor appears as the
reading.
⇒
* The zero-adjustment is made periodically.
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.
Zero
point
Zero
point
R
Time
R
Time