Protection From External Heat
Pressure transducers are sensitive to their external environment and often are protected by heat shields or insulation. The pressure transducers shown on figure 4 have been covered with zinc chromate putty to protect them from external heat so that their accuracy will not be impaired. As reported in reference 38, even sunshine on the transducer housing can cause a thermal gradient sufficient to produce a measurable error. For commonly employed strain-gage transducers, about a 1-percent change of measurement occurs for an increase of 100° F in the transducer temperature when it is functioning in its compensated operating temperature range, usually from about —65° to
+250° F. When transducers are placed on the aft regions of a motor in the direct view of the nozzle exhaust plume, additional insulation is applied to the transducer. Insulation materials that are suitable include asbestos-tape cloth, zinc chromate putty, room-temperature-vulcanized (RTV) rubber, and reflective aluminum foil.
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