Good question about cryogenic level measurement! So, most applications hold liquids with below-freezing boiling points, such as nitrogen and methane, in thermally insulated vertical 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.

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

List of DP flow manufacturers:

Other resources that might interest you

Differential pressure transmitter applied in a level measurement
Is the DP level transmitter the radar solution when implementing a DP level transmitter?

How do you use a 3D scanner for level measurement?
When should you use a 3D scanner to level measurement? 

Which is the best level principle – radar or pressure?
What’s the best level principle? And is it better to implement a radar instead of a pressure transmitter for level measurement?

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

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