Gas Detection (Australia) Pty Ltd
Page 8 of 12
M-3160-003-1 05/12/2017
Refrigerant Gas Relay Alarm Point Formula:
Vin = Alarm point Concentration / 204.8
Example;
Alarm level set point required at 250ppm
250/204.8= 1.22 V
1.
The alarm switch point is preset with 10% hysteresis to prevent relay “chatter”;
2.
The relay is non-latching and will turn off when the gas level falls to below 10% of the alarm point; and
3.
The alarm relay contacts are rated 50 V
DC
0.5 A non inductive. If heavier loads require switching a slave
relay must be used.
Calibration:
The GDA 3160 are factory calibrated to 0-1000ppm of the users required target gas and are sent out with
a certificate of calibration stating target gas information.
Functional testing may be carried out with a suitable test gas to ensure that the 4-20ma o/p corresponds
with the gas level. This should be undertaken when the unit is fully assembled and using a flow rate of
~0.5L/min of the target gas. Test gas and equipment are available from Gas Detection Australia.
When in service, if the sensor falls below a minimum working standard the o/p current will fall to
<3.00mA which will be detected at the control unit has a sensor fault.
Zero point Calibration:
A manual zeroing of the sensor can be performed when the sensor has been powered for a minimum of
one hour. The zero can be performed when the sensor is in a known fresh air, Non refrigerant gas
environment or gassed with Nitrogen. The sensor must be in one of the three above conditions for a
minimum of five minutes or until the output has reached a stable point.
To perform a manual zero:
1. Remove the GDA 3160 from the wall to access the back of the sensor unit;
2. Add a jumper to pins 1 and 3 of
P4
see picture below, This enters Manual Calibration Mode (see table
for LED sequence);
3. Press and hold the ZERO calibration button
SW1
for one second (see table for LED sequence):
If the zero was successful a short beep will be heard (see table for LED sequence)
If the zero was
not
successful a two sec beep will be heard (see table for LED
sequence). Repeat step 3 after ensuring that the sensor is in fresh air and stable.
4. When successfully zeroed remove the Manual Calibration jumper from header
P4
and return to normal
operation.
