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Bearing Oil Sensor For High Vibration Environments

The Problem

A compressor at a chemical company vibrated severely – a common problem with compressors in any industry. An important sensor used to measure the compressor’s bearing oil temperature was a field-cuttable RTD that failed frequently, forcing a compressor shutdown each time. The RTD failed for two reasons:

  1. When the company installed a new RTD they cut the sensor to length which created a sharp tubing edge that would cut the wires where they exited the stainless steel sheath as the assembly vibrated.
  2. Vibration fatigue eventually caused the internal RTD wiring or connections to break, leading to a failed open sensor.

Bearing Oil Sensor Compressor Image

The Solution

The WORM Flexible Temperature Sensor for Thermowell Temperature Assemblies from Moore Industries provided the necessary solution. It is a field-cuttable sensor, but with a unique flexible design that eliminated the sharp tubing edge that resulted from cutting the conventional rigid sensors. It has a short 1.5” long sheath with lead wires and a compression spring which allows its use in most any depth of thermowell. Instead of cutting the sensor the company only had to cut the lead wires and spring, leaving no sharp steel edge to damage the wires.

Failure from vibration fatigue in the sensor was solved with the high vibration 30G option. With this option, the WORM sensor is encapsulated in a waterproof epoxy that can endure extreme vibration levels and full water immersion. Sensors with the 30G option have been in service in many applications with high vibration conditions since 2005 and have proven to have a long life.

In addition, the WORM sensor provided other benefits. The compression spring that comes with the sensor ensures a consistently tight fit of the sensor tip at the end of the well for faster response time. The short sheath also prevents the sensor from picking up irrelevant ambient temperature which results in more accurate measurements.

To mount the WORM into the compressor’s oil reservoir Moore Industries engineers used a thin wall protection tube which allows fast measurement response to changes in oil temperature. The protection tube’s process connection is ½” NPT which includes a compression fitting so that the protection tube depth in the oil reserve could be adjusted.

Because of the WORM’s easy adaptability to any length thermowell or protection tube, its faster response time and more accurate measurement, and the 30G option’s capability of enduring a high vibration environment, the WORM provided the increased reliability that this company needed. They drastically decreased their production downtime and reduced maintenance costs in both replacement parts and manpower. 

WORM Board pp

The model number used for this application: TRX / PTB-P2C / U18-T0 / S316 / -WSPT14 -30G –SSF15 [LH2NS]

Learn more about the WORM Flexible Temperature Sensor for Thermowell Temperature Assemblies. Download the RTI-1 data sheet. Or visit the catalog.

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