The sample conditioning system of the Continuous Emission Monitor (CEM) is designed to remove moisture from the sample gas by chilling the gas and condensing the water. Liquid water before the chiller, in the sample line or at the primary filter, is too heavy for the sample pump to move. In other words, water before the chiller acts like a soft plug and greatly reduces or stops flow to the analyzers. The sample conditioning system has several self-checks that prevent liquid water being pumped into the analyzers. The status of a self-check is displayed by a light on either side of the icon. A red light indicates a failure or stoppage whereas a yellow light means the check is OK. The top icon is for the chiller. If the chiller is not cold enough the pump will be shut down. The second icon is gas flow, a red light means no or too low flow. The third icon is the moisture sensor, a red light means water is on the sensor. The pump will be off and the 2nd icon light will also be red. These checks are mirrored in the Evaps control room and show as analyzer faults on the control screen.

If any analyzer fault alarm is active check the status of the icons described above. Some of the problems can be solved easily. Before doing any maintenance or adjustment to the CEM system the data system must be put in the MAINT mode. The most common problem will be with water so check the 3^rd icon. If the light is red remove the moisture sensor, shown in green below, and dry the sensor with a soft paper towel. Form a wick with the towel and insert it into the flow chamber to absorb any other water droplets.

Once the sensor is dry the pump should restart. Let it pump dry air for about 10 minutes and reinstall the sensor. If the pump stops and the light turns red redo the above process. If the pump stalls after this second attempt call the service technician. Take the system out of MAINT.

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