cryogenic check valve with drilled hole

[simplemath]

What is the point of drilling a 3/16” bleeding hole on the disk of 10" cryogenic check valve?

Fluid temperature -265°F.

Thanks in advance

 

[dcasto]

A built in thermal relief would be my guess.

 

[simplemath]

dcasto?
Could you please explain in more detail?

In my understanding, the liquid through the hole will flash into gas, which serves as buffer between cryogenic temperature and ambient.

Thanks

 

[dcasto]

I'm assuming the check valve is on a pump or meter. Once the pump or flow through the meter is stopped, the cyogenic liquid would gain heat and expand. Again guessing more, there is no relief valve on the upstream side and there is a relief valve on the downstream side.

There maybe other reasons, but that is why I would put the hole in the disk.

 

[JimCasey]

And there is a justification to keep a trickle of cryofluid on all components in the loop to stabilize the temp. As was pointed out earlier: If the system is totally isolated, the liquid flashes to gas. Once the phase change is complete, it's just a few BTUs away from ambient temperature. When the flow resumes, the components could be thermal-shocked with potentially adverse effect.