Customer Services (858) 578-7887 & (888) GO IN
TEC
IN
TEC
Controls, 12700 Stowe Dr., Suite 110, Poway, CA 92064
Fax (858) 578-4633 & (888) FX IN
TEC
www.inteccontrols.com
Specification subject to change without notice.
Printed in USA 140225
Polygard® is a registered trademark of MSR
SPC3-11XX US
PolyGard
®
Single-Point Controller
User Manual - SPC3-11XX
Page 29
8 Gas Sensor
8.1 Description
The sensor is a micro-fuel cell, which is completely sealed. The measurement is a gas-in-liquid chemical reaction
rather than a surface area measurement. With no surface area to coat, this sensor retains its sensitivity to carbon
monoxide even after prolonged exposure to clean air.
The cell consists of a diffusion barrier, O-ring seal, electrolyte reservoir and two electrodes. The target gas, carbon
monoxide, enters the cell through a diffusion barrier. The chemical process of the measurement is one of oxidation
where one molecule of the target gas is exchanged for one molecule of oxygen. The reaction drives the oxygen
molecule to the counter electrode, generating a DC microampere signal between the counter electrodes. This signal is
linear to the volume concentration of the sensed gas rather than the partial pressure.
The transmitter electronics will provide the necessary bias voltage when configured for one of these sensor types.
Most sensors produce a small amount of baseline current in clean air. This is adjusted out with the zero push button
on the transmitter.
This oxidation at the electrodes causes wear of the sensor. Typical life for this sensor is approximately five years in
normal operation. This will vary somewhat from sensor to sensor, with some working lifetimes less than five years and
some more than 5 years. This wear also changes the characteristics of the sensor, requiring periodic re-calibration
with the potentiometer Gain. It is recommended that the sensor accuracy be verified every twelve months and
recalibrated as necessary.
8.2 Calibration
Required instruments to calibrate the transmitter:
x
Test gas bottle with synthetic air or CO-free ambient air.
x
Test gas bottle with CO (ppm) in the range of 30 – 80 % of the measuring range.
x
Calibration adapter with tube. Type:
x
Small screwdriver.
8.3
Zero-Point Calibration
Consider the running-in period of the sensor (at least 1 hour).
x
Open window SP 01 in menu “Measuring Value”.
x
Connect calibration adapter carefully to the sensor element.
x
Wait 1 minute until the measuring signal at SP 01 is stable, push button “Zero” for 5 seconds.
After successful calibration the measuring signal is corrected automatically.
If the zero-point is out of the admissible range (> 10 % of measuring range) before calibration, there is no
correction of the measuring signal. The sensor has to be replaced.
x
Remove calibration adapter carefully by turning lightly. Check the sensor for correct mounting!
Note:
Please observe proper handling procedures for test gas bottles!
x
Gas pressure regulator with flow meter to control the gas flow to 150 ml/min.
CONKIT-E/CH-
LC
See fig. 06
x
Apply synthetic air (
150
ml/min; 1 Bar (14.5 psi ) ± 10%), or CO-free ambient air.
1) Type gas depends on model #.
2) Flow rate depends on model # and diameter of element.
3) Calibration adaptor depends on model # and diameter of element.
