Specification for Transducers, Pressure and Differential, Pressure, Electrical and Fiber-Optic

This specification covers the requirements for pressure and differential pressure transducers for general applications. Pressure transducers typically consist of a sensing element that is in contact with the process medium and a transduction element that modifies the signal from the sensing element to produce an electrical or optical output. Some parts of the transducer may be hermetically sealed if those parts are sensitive to and may be exposed to moisture. Pressure connections must be threaded with appropriate fittings to connect the transducer to standard pipe fittings or to other appropriate leak-proof fittings. The output cable must be securely fastened to the body of the transducer. Most common sensing elements are diaphragms, bellows, capsules, Bourdon tubes, and piezoelectric crystals. The function of the sensing element is to produce a measurable response to applied pressure or vacuum. The response may be sensed directly on the element or a separate sensor may be used to detect element response. The following are the different types of electrical pressure transducers: differential transformed transducer, potentiometric transducer, strain gage transducer, variable reluctance transducer, and piezoelectric transducer. Different kinds of fiber-optic pressure transducers shall be discussed: Fabry-Perot interferometer, Bragg grating interferometer, quartz resonator, and micromachined membrane/diaphragm deflection. The following physical properties of transducers shall be determined: enclosure, transducer mounting, external configuration, standard electrical connection, pressure connections, damping, size, and weight. Different tests shall be conducted in order to determine the service life and overall performance of the transducers.