The sample system uses the Simrad GD10P IR detector. The GD10P is factory calibrated for 9-100% LEL Pentane.
The
Simrad GD10P detector cannot be poisoned, and it does not require any
calibration. However, the GD10P detector can be checked for proper
operation by applying test gas to the sample system. The GD10P detector
will provide a 4-20mA-signal output. The 4-20mA output is then sent
to the flow meter and the GDS C2 controller. The C2 controller will
provide a digital display of the gas concentration, and provide both
4-20mA and alarm/fault relay outputs. 120VAC is required for
operation. See the Simrad GD10P transmitter, and the GDS C2 manual for
complete operation.
The system uses a flow switch to alarm when
the flow is interrupted. The switch will alarm if the system aspirator
is set to low or is non-functioning. In addition, the switch will alarm
if the sample line/system filters are plugged. The flow switch uses
the transmitter 4-20mA output signal to activate the C2 controller A3
level fault alarm system. This is set to operate if the transmitter
signal falls below 4mA. A set of dry contacts located on the relay
option board is used for this function. This A3 fault relay is assigned
to relay number 3 on the optional relay module. 120V can be connected
to this relay for remote use.
The system design is based on a dry
gas sample to the monitor. A system particulate filter will help
remove any dirt entering the detector. A three-way valve is used to
test the detector or proper operation. A system flow meter is used to
regulate the process gas .5-1 LT/M flow rate to the detector. The flow
meter should be set to 50 on the flow meter scale.
The sample
gas is drawn into the monitor by an air-operated system aspirator (air
consumption is approximately .27 SCFM). The compressed air regulator
adjusts the aspirator vacuum flow. By adjusting the regulator process,
and by adjusting the flow meter needle valve, the system can be set for
.5-1 LT/M flow rate. To conserve instrument air, and not to develop a
high vacuum in the transmitter, the regulator should be set to the
minimum pressure to maintain the proper flow rate. The process gas with
the compressed air exits out of the monitor at the gas outlet fitting.
The gas must be vented to a safe area with minimum backpressure.
