Sentry Industries 5000 User Manual

 

 

3.  Using a Sierra Monitor Model 1200-26 Gas 

Calibrator with a Sierra Monitor Model 5358-00 
calibration adapter, or Model 5360 Gas 
Delivery Fitting. Apply the calibration gas at a 
flow rate of 100 cc/min. until the signal out 
voltage stops changing (approx. 2 minutes).  
Then adjust span adj. potentiometer to the 
calculated value. 

4.  Remove the calibration gas and wait for the 

voltage to drop.  If the voltage is below 0.30 
VDC the procedure is complete.  If the voltage 
is above 0.30 VDC repeat the zero and span 
adjustments. 

5.  Calibrate the sensor using the instruction manual 

procedure. 

• 

A 

 message during 

calibration indicates one of the two 
conditions for a combustible sensor: 

• 

The zero gas voltage must be less than 
.3 volts.  

• 

The new span change (span voltage less 
zero voltage) must exceed 30% of the 
calculated span change. 

For Example: 

Zero gas voltage = .20 VDC 

Span voltage = .43 VDC 

Span change is .43-.2  = .23 VDC 

As the calculated span value (from step 
5 above) is 1.03, the calculated span 
change is:  1.03-.2 = .87 

By calculation: 30% of .87 = .26 

The new span change (.23) is less than 
30% of the calculated span change so a 

 message will be 

displayed. 

The 

 calculation is made to insure that 

the calibration does not adjust the electronics so that the 
"gain" is large enough to cause false alarms due to minor 
drift or due to minimal electronic noise. 

If any 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 7-4 provides the 
pin out for the sensor assembly. 

1 

DETECTOR 

WHITE 

2 

COMPENSATOR 

BROWN 

3 

CALIB. SW. 

RED 

4 

DETECTOR 

BLACK 

5 

DRAIN 

BARE 

6 

CALIB. SW. 

GREEN 

1.  Detector element  resistance should be between 1.5 to 

2 ohms. 

2.  Compensator element resistance should be between 

1.5 to 2 ohms.  

3.  Calibration switch 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 electronics and sensor which are removed should be 
returned to the factory for evaluation). 

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

• 

Make the bridge voltage adjustment 
immediately to avoid over-voltage damage to 
the sensor. 

• 

Use diagnostic code 0020 to establish nominal 
value calibration. 

• 

Allow 24 hours for full stabilization of the 
sensor, recheck the zero and span adjustments 
and calibrate the sensor module.