Sentry Industries 5000 User Manual

 

 

The Combustible Gas Module includes the sensor 
and electronic  assembly installed in an explosion 
proof housing.  The sensor screws into one hub of 
the enclosure and plugs into the bottom electronics 
card via a six pin connector.  Cabling to the 
controller connects to a three pin spring loaded 
terminal strip.  

Electrical adjustment, or replacement of the sensor 
will be necessary under the following conditions: 

• 

Controller displays the following error 
messages: 

 

• 

False readings or alarms are received 
due to sensor inaccuracy. 

Warning: : During sensor adjustments the 
concentration reading on the controller will be 
inaccurate and alarm level concentrations may be 
displayed.  If false activation of the alarm relays 
will cause a problem disconnect the relay wiring 
prior to adjustment or turn the module off using 
the 

 mode. 

Prior to reading voltages and making adjustments perform 
a visual inspection to confirm that there are no physical 
problems such as water in the electronics enclosure, 
wiring damage or corrosion. 

Use  Figure  7-6 to locate test  points during the following 
procedures: 

Caution:  The area must be free of flammable vapors or 
gases during any adjustments or maintenance procedures. 

Confirm that no combustible gas is present and remove 
sensor module cover. 

Comparing to the "GND" (ground) test point measure 
"BRIDGE VOL" (bridge voltage) and adjust to 2.00 VDC 
using "BRIDGE ADJ" potentiometer.  Turn counter-
clockwise to increase. 

Comparing to ground measure 

 and adjust to 

0.18 VDC by turning 

 potentiometer.  Turn 

counter clock-wise to increase. 

1.  Determine the concentration of the calibration 

gas (CG) in % LEL. 

2.  Use the following formula to determine the 

response to the calibration gas at 

. 

Voltage (Signal Out) = (CG+12)/60 

For Example:  

If CG  = 50% L.E.L 

Signal Out = (50+12)/60 

= 1.03 volts