Controller Calibration
If the system is being calibrated using the “Controller
Calibration” method, the most accurate calibration for
a new sensor will be achieved if a transmitter calibra-
tion is performed first (as soon as the sensor output
has stabilized). Then perform the “Controller
Calibration” procedure described in the “Calibration”
section (24 hours later for maximum accuracy). The
controller calibration procedure can then be used for
all subsequent calibrations.
Transmitter Calibration
1. Plug the calibration meter into the transmitter.
2. Allow the sensor output to stabilize (several hours
for maximum calibration accuracy), then perform
the Transmitter Calibration procedure described
in the “Calibration” section.
3. When the calibration is complete, remove the cali-
bration meter and place the cover back on the
transmitter enclosure.
4. Press the controller RESET button. The controller
returns to the normal operating mode (after a time
delay).
For the highest degree of calibration accuracy, per-
form a second calibration after 24 hours.
A Recommended Test Form is supplied at the back of
this manual for recording maintenance performed on
the system.
TROUBLESHOOTING
Table 5 is intended to serve as an aid in locating the
cause of a system malfunction.
NOTE
Record all faults on the Fault Record Sheet sup-
plied with this manual.
LOSS OF SENSOR SENSITIVITY
There are a variety of factors that can cause a
decrease in the sensitivity of catalytic type com-
bustible gas sensors. Interfering or contaminating
substances that can adversely affect the response of
the sensor to combustible gases are as follows:
A. Materials that can clog the pores of the sintered
metal flame arrestor and reduce the gas diffusion
rate to the sensor are:
1. Dirt and oil.
A dust cover should be installed to protect
the flame arrestor whenever these conditions
exist.
The dust cover can be cleaned as part of rou-
tine maintenance. This can be accomplished
using an organic solvent and an ultrasonic
bath.
2. Corrosion products.
This occurs when substances such as Cl
2
(Chlorine) or HCl are present. A dust cover
provides some protection. The dust cover
should be replaced as part of routine mainte-
nance.
3. Flame arrestor clogged as a result of painting
or house cleaning.
The routine maintenance procedure should
include covering the sensor with a plastic bag
when painting or cleaning. The bag should be
removed as soon as possible when the pro-
cedure is complete.
4. Polymer formation in the flame arrestor.
This can occur where monomer vapors such
as 1-3 butadiene, styrene, isoprene, etc. are
present.
B. Substances that cover or tie up the active sites on
the catalytic surface of the active sensing ele-
ment.
This occurs in the presence of volatile metal
organics, gases, or vapors of hydrides, and
volatile compounds containing phosphorous,
boron, silicone, etc.
Examples: RTV silicone sealants
Silicone oils and greases
Tetraethyl lead
Phosphine
Diborane
Silane
Trimethyl chlorsilane
Hydrogen fluoride
Boron trifluoride
Phosphate esters
Significantly longer sensor life can be obtained by
using the Det-Tronics poison resistant sensor.
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