Pressure transmitter improves valve test rig productivity

A leading global manufacturer of hydraulic valves and manifolds for the mobile and industrial equipment markets is upgrading pressure measurement equipment used on their hydraulic production test rigs to improve productivity.

A variety of sophisticated rigs are used to check quality and functionality of an extensive range of precision valves and manifolds used for performance and safety critical applications such as agricultural and material handling vehicles. 

Typically the hydraulic load applied is within a range of 0 to 400 bar and the pressure transmitters have to deliver a highly accurate, stable and reliable electronic output whilst operating in a physically demanding and high volume production environment with considerable shock and vibration loadings. In particular the test programs include full range hydraulic pulsing and ramping.

Due to problems experienced with the original pressure transmitter such as signal drift and mechanical integrity of the removable electrical connector assembly, Hydrotechnik’s HT-SML was successfully tested and selected for replacing the existing transmitters used across the entire range of test rigs in the company’s UK based European HQ and manufacturing facility.

The original pressure transmitters employed a “wet cell” Silicon measuring element which uses a fluid filled stainless steel isolation diaphragm to transmit the applied pressure value. The 4 wire electronics were configured for 0 - 10V output /12-32Vdc supply with internal zero / span adjustment potentiometers accessible by removal of the electrical DIN plug assembly.

Valve productivity

Due to signal drift experienced when used in the application, each transmitter would require periodic checks and adjustment to ensure that it’s performance is kept within precise tolerances. The potentiometers are very small and located inside the transmitter body, so the required adjustments could not be carried out in-situ, necessitating removal of each transmitter from the machines as and when required. Also due to ambient machine vibration levels the removable plug assemblies were often becoming loose causing ingress of machine fluid and sensor failure. Both issues inevitably led to significant machine downtime with corresponding loss in overall production efficiency.

The replacement pressure transmitters from Hydrotechnik’s HT-SML range feature thin film silicon technology. This uses a thin layer of silicon sputtered directly onto a stainless steel diaphragm to produce a single integrated measuring element with no fluid isolation and the rear electrical plug assembly is a fixed design with no internal potentiometers. The result is a highly rugged and reliable sensor that is very suitable for high pressure hydraulics and proven to be significantly more accurate, stable and reliable in this application.

Due to the HT-SML performance (accuracy <0.25% range including all ambient temperature error sources) zero and span adjustments are not necessary to maintain the required production measurement tolerances.

The result is improved test productivity and lower measurement costs.

Watch our HT-SML product animation below - feel free to get in touch on 0115 9003 550 / for more information.