Dwyer DPM - Manual (Page 38)

Particulate Monitoring Systems
Installation & Operating Manual
Document No. 210-1003-M Page 31 ©2007
9. Troubleshooting
The following is primarily used when troubleshooting a system without the optional automatic self
checks. When troubleshooting, consider each component of the system: The control unit, the sensor
coax cable and the sensor assembly.
False High Signals (False Alarms)
1. When an apparent false high signal is present, first check the process to be sure the particulate
level has not increased. Keep in mind that the system can detect very low levels. In filtration
applications the system can detect invisible particulate levels and very small emissions.
2. Check the sensor cover and conduit seal to be sure they were not left open allowing rain to enter
the housing. Check the coaxial cable connectors using a digital voltmeter and check for shorts. If
nothing can be found, conduct a manual system zero check.
No Reading or Alarm (When Believed Necessary)
1. Increase the particulate level or introduce particulate into the air stream and monitor for a response.
If the system responds properly re-evaluate the selected alarm points and the process conditions.
2. If there is no response, check for electrical continuity from the sensor to the control unit end of the
coax cable.
3. Contact the factory for a Field Test Unit that can generate a signal to check response and
calibration.
10. Routine Maintenance
EQUIPMENT MAINTENANCE
• Only appropriately licensed professionals should perform maintenance on
this product.
• For operator safety and to prevent ignition of flammable or combustible
atmospheres always disconnect power before servicing.
Particulate Sensor: There is no electronic calibration or zero adjustment for the sensor. The sensor
does not normally need any cleaning and for optimal performance, routine cleaning of the sensor is
not recommended.
Control Unit: The viewing window, keypad and enclosure may be cleaned with soap and water as
needed. Use a soft cloth to prevent scratching the window. Do not use an abrasive pad or any
chemicals that will attack plastic or Lexan.