Stable and accurate temperature signal readings in natural gas compressors with heavy engine vibration

A number of applications require signal conditioning devices to operate in extremely harsh environments – natural gas compressors with heavy engine vibration is one example...


An Italian manufacturer of natural gas compressors selected the PR 5333D transmitter for its compressor engines because of the transmitter’s ability to deliver high quality temperature readings in an ATEX area with heavy vibration…


Example of a natural gas compressor station – courtesy of


Safe S.p.A. is one of the world's leading manufacturers of natural gas compression solutions for commercial and industrial applications. The company specifies the PR 5333D 2-wire programmable transmitter when designing heavy-duty gas compressors for reliable and efficient operation throughout a wide range of conditions for specific customer needs.


Mr. Gianluca Bertacchini, COO of Safe S.p.A., says:


“The operating environment of natural gas compressor stations includes a combination of heat, pressure and vibration. We need stable oil and methane gas temperature readings when using PT100 probes in environments with heavy compressor vibration – we have selected the PR 5333D transmitter for an ATEX area with heavy vibration and we are happy to have learned that it is able to provide the required stable, high accuracy signal measurement we require”.


Safe’s compressors with high capacity include mother stations, booster versions for daughter stations, and special units designed for oil & gas and biogas applications, etc. The compressors can be driven by either an electrical motor or a gas engine.


Thank you

We sincerely thank Mr. Gianluca Bertacchini, Safe S.p.A., for participating in this article.




Comment from the PR electronics specialist:


The main task in this case was to achieve high quality temperature readings in an ATEX area.

This was solved by choosing the EMC robust PR 5333D transmitter with ultra-high accuracy (19 bit input and 16 bit output resolution) and multiply IS approval listings (ATEX, FM, CSA, INMETRO, CCOE and EAC).


In this case, however, there was also a demand for installation in a heavy vibration environment.

PR electronics has a strong background in developing products and solutions for the marine industry.The PR 5333D has a DNV.GL marine approval where the product have passed a special vibrations test after the B-criteria for directly mounting in a heavy vibration environment.


A typical natural gas application requires precise control and monitoring.


Lubrication systems protect compressor components from increased amounts of wear and deposit formation and help the equipment run cooler and more efficiently. Many different lubricants with different basis oils are being used. The lubrication fluids are typically stored in stainless steel and carbon steel tanks. To secure continual lubrication the tanks are being monitored for level using both 2-wire style level transmitters and level switches. The applications are rated I.S. so robust and precise isolation barriers are needed to bring the signal back to the safe area for connection to the control system.


Our recommended solution is to use a 9106BB (double channel HART transparent repeater) for both the temperature measurement and the level transmitter, where the built-in loop supply in the 9106BB powers the two-wire devices and on the safe side replicates a precise 4 – 20 mA signal for the control system. The level switch is directly connected to the 9202B pulse isolator which delivers a relay output to the controller on the safe side.




Niels Præst, Product Commercialization Manager, PR electronics


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