ROBERT E ZUCKERMAN
Engineering in Glen Cove, NY

4111048, Sep 5, 1978

Mar 21, 1977

5/779736

Robert E. Zuckerman - Glen Cove NY
Michael J. Merendino - Brooklyn NY

G01N 2562

73338

An improved fluid parameter sensing apparatus particularly adapted for comparing one value of at least one air parameter as sensed at a first location in an air treatment system with at least one other value of the air parameter as sensed at at least a second location in the air treatment system includes a housing defining a pneumatic chamber; first means for feeding a stream of air from the first location to the housing; second means for feeding a stream of air from the second location to the housing; means for alternately admitting air from the first and second air stream feeding means to the chamber; sensing means disposed in the chamber for providing an output signal proportional to the at least one air parameter; means connected to the output of the sensing means for comparing a first output signal from the sensing means with a second output signal from the sensing means, the second signal being spaced in time relative to the first signal; and means operatively connected to the air admitting means for controlling the operation of the comparator means in synchronization with the operation of the air admitting means, the controlled operation resulting in the first output signal from the sensing means being proportional to the one value of the air parameter and the second output signal from the sensing means being proportional to the other value of the air parameter.