Profile: Datatest Industries, Inc. offers emission control and monitoring equipment. The DT109 opacity monitor measures opacity as well as mass emissions. It enables process monitoring with instant and average 4-20 mA outputs. The 201LP triboelectric detector is a three wire particulate monitor that measures particulate levels in air ducts on a real time basis. It is powered by an external 24V DC supply, and its continuous 4-20 ma output can be connected directly to a PLC, recorder, or digital readout.