Selecting an appropriate transducer involves making a detailed analysis of the specifications provided by the manufacturer. This is done to ensure that the transducer meets the environmental test conditions, the measurement requirements, and the measurement error allowance. Environmental conditions can include temperature, pressure, humidity, vibration, radiation, and water resistance. Measurement requirements can include operating range, frequency response, space limitations, output signal compatibility, operating life, mounting requirements, and test fluid compatibility. The measurement error allowance provides input into the total measurement uncertainty analysis described in chapter 18, section 18.5, "Uncertainty Versus Accuracy." Before incorporating the selected transducer into a measurement system, a preliminary analysis of the potential error sources and their possible corrections should be performed prior to the uncertainty analysis to verify that the selected transducer alone has sufficient measurement accuracy. This analysis should be done before the transducer is purchased or before the final design of the measurement system.

Bench tests of the transducer's performance must be carried out for any conditions or combination of conditions not specified by the manufacturer. Similar tests are required if the transducer is modified or mounted in ways not specified by the manufacturer.

Reputable and successful transducer manufacturers will provide all the information available on their products and will usually be able to provide the test data to confirm their specifications. Suppliers that sell equipment made by another manufacturer under their own name may not be able to provide complete information. In this case, you may have to determine who the original manufacturer...