Selecting the Right High Temperature Industrial Pressure Transducer for Liquids or Gases

When selecting an industrial pressure transducer for monitoring high temperature liquids or gases be sure to check the operating temperature range of the transducer, in order to select the correct pressure transducer for these applications.

This specification for temperature is included under environmental data on most manufacturers' data sheets. The temperature compensated range specification of a transducer is the error introduced as temperature increases or decreases from 70°F. This thermal error affects both the span and zero setting of the transducer's analog output and is generally listed as a percent of full scale per degree (% FS/°F). Thus, the static accuracy (accuracy at 70°F) of the pressure transducer plus the thermal error introduced by a high temperature pressure source is the total possible error for a specific high temperature pressure measurement.

The expense of a special high temperature pressure transducer can be avoided by using a temperature stand-off (short length of tubing) to isolate the transducer from the high temperature pressure media. The chart below shows various lengths and diameters of tubing for 303 stainless steel and brass that will limit the media temperature at the transducer to 0-200°F. This chart assumes the ambient temperature around the transducer is 100°F and the major source of thermal input is via the connecting tubing.

As an example, a 6 inch length of 1/4" O.D. 303 stainless steel tubing will protect a transducer from an 1100°F pressure media.

Note: In order for the standoff to be effective, it should be pointed straight down or within 45° of vertical.