A question that is coming up more and more often for DP Flow is, what are the best practices for measuring cryogenic liquids?
While many standard DP Flow products can be used in cryogenic applications without issue, below are a couple tips to help ensure a successful installation-
1. Utilize a primary element without welds in the flow stream (especially dissimilar metals) as extremely low temperatures can lead to brittleness in the metal.
2. Mount the transmitter above the flow point (contrary to the recommendation for normal liquid installation) to ensure a gas barrier is present to insulate the transmitter from cryogenic temperatures.
3. Utilize small diameter (1/4" recommended) impulse tubing. This helps to prevent cold liquid from contacting the transmitter diaphragms.
3. Do not insulate the impulse lines leading to the transmitter.
4. Avoid "flow-down" situations. If installation in a vertical line is necessary, flow up is preferred.
5. Instrument gaskets and O-rings should be PTFE, which provides better sealing performance at low temperatures than graphite.
What other challenges do you have when using DP Flow on cryogenic liquids? Add your questions or tips in the comments below.