Most applications hold liquids with below-freezing boiling points, such as nitrogen and methane, in thermally insulated vertical cryogenic tanks. Still, the tank will always have a gas pressure head for the liquid vapor. Also, these fluids have low oxygen permeability, or Dk values, which make radar devices a poor choice for cryogenic level measurement.

Cryogenic level measurement using a differential pressure transmitter

Differential pressure transmitters can compensate for the vapor pressure head and measure the level accurately. Also, wet or dry legs with some slant will help reduce turbulence from boiling and condensing outside the insulation. If you use wet legs, then you should use liquids with low freezing points.

Cryogenic level measurement
DP transmitter, wet/dry leg, with cold temperature fluid – Courtesy of Emerson Automation Solutions

If you are wondering how to measure level using a differential pressure transmitter, don’t worry. We have a detailed guide here.

Got any more questions about cryogenic level measurement? We are here to help.

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