Dwyer PMT - Manual (Page 22)

Particulate Monitoring Systems
Installation & Operating Manual
Document No. 210-1015-F Page 16 ©2007
Pass:
1. Disconnect power to the control unit.
2. Open the sensor enclosure cover and re-attach the coaxial cable center
conductor to the sensor probe end.
3. Close the sensor enclosure cover and proceed to the sensor zero check.
Fail:
1. Check cable installation and routing instructions in the Installation section
of this manual for proper cable installation. Make any changes necessary.
2. Contact the factory for further assistance.
Once the control unit and coaxial cable zero have been checked, proceed to the Sensor Zero Check.
To perform the sensor zero check the process flow must be stopped or a sensor test pipe (available
from Factory) or length of metal pipe will be needed (4”-6” diameter pipe or larger). The pipe should
be at least 3 in (8 cm) longer than the probe itself and must be grounded. The length of pipe will serve
as an electrical shield for the probe while it is out of the process.
Sensor Zero Check
1. Do not remove the sensor from a running process if it will in any way
compromise personnel or plant safety procedures.
2. Disconnect power to the control unit.
3. Remove the sensor from the process and insert it into the grounded metal
test pipe.
4. Re-apply power to the control unit and allow the reading to stabilize for 1-2
minutes.
5. Monitor the transmitter’s mA output. Its scaled value should be well below
its specified minimum detection level. If the sensor passes this check there
are no false signals from the sensor.
Pass:
1. Disconnect power to the control unit.
2. Remove the sensor from the grounded test pipe and re-insert into the
process.
Fail:
1. Contact the factory for further assistance.
When performing a zero check, keep in mind that it may be acceptable to consider a small false signal
negligible. For example if the baseline readings are 100pA and a system zero offset of 1pA was
found, this is only a 1% affect on the normal readings. If using the device for basic flow/no flow
detection or basic emissions detection, this would not be significant.