Liquified nitrogen system operation 2

[enguest]

Sirs,

I am working on the project which includes the replacement of manual type of operation of liquified nitrogen system (storage and vaporizer) with automatical type.

Now the liquified nitrogen storage is connected to vaporizer and being operated manually. Flow is being controlled by valve (one of DBB valves) located just downstream of the liquified storage and before vaporizer.
We are going to put a control valve downstream of vaporiser. This control valve will be activated as pressure in the main nitrogen supply system is below the normal operation pressure.
Could you please help me to find if it is any safety related issue associated with our modification?

 

[StoneCold]

We have a gaseous nitrogen header that is fed from a vaporizer. We control the pressure in the header with a forward pressure regulator. It is downstream of the vaporizers. We have ours set up so that we switch between two vaporizers every 12 hrs. This helps keep the ice buildup down and the exit temperature up. You need copper or stainless piping due to the low temperatures. Use silver solder if you use copper. We placed our switching valves downstream of the vaporizers to keep them out of the liquid nitrogen area. You need relief on any line that has liquid in it that can be blocked in because the pressure builds very fast. Use a valve type that does not have a cavity that can fill with liquid nitrogen and burst.
Check with your supplier. A lot of companies have Nitrogen under PSM and they have some policies that you need to follow.

Regards StoneCold

 

[BenThayer]

low temperature interlocks are not uncommon.

if your "take" is greater than the vaporizer's sizing, you can have liquid entering the header piping. typically, the main headers are not of a design that they can take either very low temperatures or thermal shock.

 

[enguest]

Sirs,

Thank you very much for your help.

StoneCold,

What does PSM mean?

 

[StoneCold]

enguest
PSM is process safety Management. It is a policy/practice mandated by OSHA in the US for large volumes of potentially hazardous materials. The danger from liquid Nitrogen obviously being freeze contact and suffocation.

Regards

StoneCold