The CEM68 transit-time flowmeter for stacks is designed to meet the requirements of the 1990 Clean Air Act amendments, including self-calibration checks. It accepts relative accuracy K factors for standardization to a reference-method device. The CEM68 measures standard and actual volumetric flow rate using a microprocessor-based electronics section and two or more ultrasonic transducers. No regular maintenance is required, even under the harsh conditions of stack monitoring. The meter has no moving parts, holes or orifices to clog and is adaptable to virtually all installation requirements.

The CEM68 flowmeter meets EPA requirements for self-error check. Automatic calibration routines are performed on a timed interval or upon demand, activating calibration and fault relays. The resulting status is logged via the meter’s RS232 interface. Additionally, multipoint calibration data can be entered into the CEM68 to standardize it to a reference-method calibration.

Adaptable installation configurations reduce installation costs. The meter’s electronics can be located up to 1,000 ft (305 m) from the transducer installation. Outputs include a liquid crystal display of standard and volumetric flow rate, actual flow velocity, totalized flow rate and diagnostic messages. Analogue and digital outputs are also standard.