Hydraulic Coupling
Incompressible silicone fluid seals sensor diaphragms from harsh process fluids while transmitting applied pressure. Operating an oil filled isolator involves capturing process fluid pressure on a flexible outer isolation diaphragm, which transfers force through an internal oil volume to a primary MEMS sensing element. The fluid fill provides continuous hydraulic coupling while protecting delicate internal electronics from corrosive chemicals, viscous media, and mechanical abrasion.
Bubble-free vacuum filling ensures linear pressure transmission across full operational ranges. Thermal expansion of the internal oil volume exerts additional pressure on the sensing diaphragm, introducing temperature-dependent zero shifts that require active electronic compensation.
Fluid Compression
Fluid compressibility dictates dynamic response speed and transmission fidelity in pressure isolators. High bulk modulus silicone oils transmit fast pressure transients without signal attenuation. Vacuum degassing processes eliminate dissolved gases that introduce fluid compliance and dynamic phase lags.
Dynamic pressure testing verifies response bandwidth across target operating frequency ranges.
Temperature Response
Thermal expansion at high temperatures alters internal baseline hydraulic pressure against sensing diaphragms. Thermal offset compensation algorithms adjust digital output values based on internal temperature sensor readings. Isolation oil selection balances low thermal expansion coefficients with high chemical stability.
Temperature cycling tests evaluate zero-shift repeatability.
Leak Detection
Diaphragm pinholes or weld defects allow fill oil loss and introduce measurement errors. Helium mass spectrometry testing inspects isolated assemblies for micro-leaks prior to oil filling. Verification protocols validate seal integrity at maximum working pressure limits.
