Can Water Hammers Cause Damage to Temperature Sensors?

Control and instrumentation engineers should consider the pipe infrastructure downstream of pumps, where conditions during start-up or momentary cavitation have been known to cause a highly accelerated movement of the liquid column. These water hammers can have a destructive impact on pipe-mounted process instruments such as temperature controlling and measuring devices.

Thermometers using resistance temperature detectors (RTD) are typically designed for accelerations up to 3g under the standard industry norm IEC 60751. Under certain conditions water hammer can produce forces far greater than 3g, causing damage to the sensor installed in the tip of the measuring insert.

In search of robust and reliable temperature measuring solutions for these high-stress scenarios, Endress+Hauser has developed a unique temperature measuring insert rated to withstand forces up to 20 times the norm. By embedding the delicate platinum (Pt100) sensor tip in a special protective ceramic filling compound, impact resistance was considerably increased without sacrificing measurement performance.

The iTHERM StrongSens technology successfully passed laboratory stress testing exceeding 60g (limited only by the test bench equipment) without any impact on its measurement accuracy or service life. The technology has since been widely adopted and deployed in critical processes by customers worldwide. Temperature instruments equipped with this technology are particularly appreciated in safety-related measuring loops, significantly improving the SIL characteristic values.