Bacharach GDC-150 Operation Manual - page 26
GDC-150 Operation Manual
20
5209-9000 Rev 0
IMPORTANT:
If the user attempts to null adjust the sensor without
applying zero air and the sensor detects background gas the amber
LED flashes to advise the user that it is out of tolerance.
5.8. Calibrating the Span Value
Step
Calibrating the Span Value Procedure
1
Attach regulator to cylinder of span gas.
2
Insert the calibration adapter into the sensor opening in the front of the
enclosure door. Use a slight twisting motion as you gently push the
calibration adapter into the sensor opening. If the calibration adapter is
hard to insert, moisten the “o” ring seal slightly then try re-inserting it.
3
Open regulator valve fully and allow span gas to flow over sensor.
4
Move the jumper to J4 position (see Figure 4-1 on page 15). The tri-color
outer LED will change to a steady amber color. The system now waits 30
seconds to ensure the user is flowing span gas.
5
The GDC-150 then enters a count down (180 seconds for catalytic and
solid-state sensors, 150 seconds for Electrochemical sensors) during
which time it adjusts the circuit to the span value which was set earlier
(see “Setting the Span Gas Value”).
If the user wishes to view this, attach meter leads to test points TP1 and
TP2 (see Figure 1-4 on page 3). The meter will show an increasing
voltage indicating the GDC-150 sensor is responding to the span gas and
the circuit is being adjusted for accuracy. Alternatively, If the optional
LED digital display has been fitted, read the value indicated on the outer
digital display. Once the count down is finished, the outer LED changes
back to green indicating the procedure is complete.
6
Before removing the span gas, move the jumper back to its resting
position (J1) and the new value is saved.
IMPORTANT:
If the user attempts to span adjust the sensor without
applying span gas or the proper value of span gas, the sensor will
produce a response that is outside of the circuit preset tolerance value.
The amber LED flashes to advise the user that it is out of tolerance.