35-3010A-12 Sample-Draw Detector • 17
6.
If necessary, use a small flat-blade screwdriver to adjust the zero pot until the voltmeter
reading is 100 mV (± 2 mV).
7.
Close the housing door.
Operation
Normal Operation
During normal operation, the Pilot LED will be on and the flowmeter will indicate about 1.2
SCFH. The current gas readings will be indicated at the controller. See the controller’s operator’s
manual for a description of the reading indications.
Low Flow Alarm
If the flowrate falls below 0.6 SCFH (±0.2 SCFH), then the sample draw detector will initiate a low
flow alarm. In a low flow alarm the Fail LED will turn on and the pump will shut off. In addition,
the CO and H
2
S sensor signals to the controller will be interrupted by the sample draw detector
resulting in a failure indication for the CO and H
2
S channels at the controller. If a low flow alarm
occurs, press the pump reset switch for about 2 seconds to restart the pump, turn off the Fail LED,
and resume proper sensor signal transmission to the controller. If the condition continues, find the
cause of the reduced flow, correct it, and restart the pump with the pump reset switch. A flow
reduction can be caused by a flow blockage, a leak in the flow system, a malfunctioning pressure
switch, or a malfunctioning pump.
NOTE:
There is no flow fail indication for the oxygen channel on the 35-3010A-12.
Maintenance
This section describes maintenance procedures. It includes preventive maintenance procedures.
This section also includes procedures to troubleshoot the sample-draw detector, replace
components of the sample-draw detector, and adjust the low flow setting.
Preventive Maintenance
This section describes a preventive maintenance schedule to ensure the optimum performance of
the sample-draw detector. It includes daily and quarterly procedures.
Daily
1.
Verify that the pilot light is on.
2.
Verify that the flowmeter indicates a flow rate of approximately 1.2 SCFH.
If necessary use the bypass valve or flow adjust potentiometer to adjust the flow rate to 1.2
SCFH.
3.
Verify a reading of 20.9% for the oxygen channel (434 mV at the oxygen transmitter test
points), 0 ppm for the CO channel (100 mV at the amp 1 test points), and 0 ppm for the H
2
S
channel (100 mV at the amp 2 test points). Investigate significant changes in the reading.
Quarterly
Calibrate the sample-draw detector as described in the “Calibration” section on page 14.