Sentry Industries 5000 User Manual

 

 

To adjust the sensitivity apply 20 ppm hydrogen sulfide 
for five minutes for full stabilization.  (Check that the 
voltage drops by at least .3 volts during this time.) Adjust 
the signal out value to .6 VDC using the range adjust 
potentiometer.  Remove gas and verify that the voltage 
climbs to above 1.0 VDC in five minutes. 

If either of the above adjustments cannot be completed 
successfully the sensor and/or electronics will require 
replacement. To check the sensor unplug it from the 
electronics and remove from the housing so that continuity 
and resistance tests can be made.  Table  7-3 provides the 
pin out for the sensor assembly. 

1 

SENSOR FILM 

GREY 

2 

HEATER 

RED 

3 

HEATER 

RED 

4 

SENSOR FILM 

GREY 

5 

CALIB. SW. 

GREEN 

6 

CALIB. SW. 

GREEN 

1.  Sensor Film resistance (grey wires) should be 

above 10K ohms. 

2.  Heater resistance (red wires) should be between 

20 and 35 ohms. 

3.  Calibration switch (green wires) should be open 

in normal operation and should close when the 
calibration magnet is applied. 

If the sensor fails any of these tests it should be replaced.  
If the sensor passes these tests the electronics are suspect 
and BOTH the sensor and electronics should be replaced.  
(The failed components should be returned to the factory 
for evaluation). 

When a new sensor is installed the following actions 
should be taken: 

1.  Input new factors into controller. The factors are 

written onto the sensor connector label.  (Three 
numbers: ###-###-###) 

2.  Make a preliminary power adjustment to insure heater 

is below 400 mW. 

3.  Force calibrate the sensor module. 

4.  Wait 24 hours for stabilization of the sensor film. 

5.  Make the power and sensitivity adjustments as 

described above. 

6.  Calibrate the sensor. 

Table  7-4 may be used during adjustment of Hydrogen 
Sulfide sensor heater voltages.  Make small adjustments to 
the Heater Adjust potentiometer until the corresponding 
Heater Voltage and Heater Current readings are obtained.  
Both values are read as voltages.