Nitrogen assist dangers?

Hello what dangers are common when doing a nitro assist with solvent at -60 to -80c?

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Too much nitrogen in your work environment will kill you. Get an O2 sensor for the work space. Place it near the process.

Also, don’t over pressurize the vessel—use a regulator to regulate pressure into vessel down.


over pressuring your vessel.
the clamps/gaskets will generally fail first.

make sure you have a prv with proper ratings and a good regulator.


I was examining an ets extractor the other day and the prv’s are set at 350 psi. Shouldn’t they be set much lower, just slightly above working pressure regardless of that systems max psi


The local extraction store near me now only sells PRVs set to 750 psi

They also recommended them for n2 assist


go to hydraulic hose fitting store such as “parker store” :speak_no_evil:


technically high quality 6in clamps/gaskets are good for 300psi, but i wouldn’t push it much past 150.


Any recommended o2 sensors?

I thought I was crazy with my 220psi prvs. I just bought 150psi ones to change them out when I redo all my taping and pressure testing


Shit, I rock 75 psi pressure relief valves!


Saw pictures today of a stainless solvent tank that did not look super happy with being pressurized to 165PSI.

Operator was extremely fortunate that the bulges he documented were not a rupture. I’m only guessing there was nitrogen involved.

Could have been atmosphere.
Might just have been hot (~45C!)

Seems fairly unlikely he hit 100% full but somehow failed to burst the tank :thinking:

It wasn’t me telling him to toss the tank, so I didn’t get to ask about PRVs or why he would even think about running the same tank again.

Over-pressurizing is one of the very real dangers of running nitrogen. If you asked nicely, you could probably acquire a 10,000 psi nitrogen tank. 3000 is more common I believe. Either way, if your regulator fails, or someone who doesn’t understand how the work “adjusts” it for you, you can be out of bounds pretty quickly. Buying a decent one, ideally one you can lock, is a start.

Pressure Relief Valves set to release before anything else fails, preferably ones that can be plumbed to a safe place (evacuated tank?) are a must.

As is a good understanding of how your solvent or blend responds to temperature (linked under “been hot” above).


Tanks rated for 150psi of more I do believe. I dont ever plan on going over 40-50 psi though when running nitrogen and I have a 50 dollar basic regulator. What’s the ideal regulator one should use

could you share the pics of the bulging? I’m curious to see what that looks like


I can. Here. Take a look.

The clamp gave our way before the warping. But it didn’t happen fast enough.

I was told dude left tank without purging the nitro off over night and care back to a warped tank. He left it in dry ice overnight. The ice melted. Created much added pressure. Tank warped.


hot damn that would be scary to see for sure. Thanks for posting, always nice to have this in the back of your mind

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The ONLY 2 times ive seen this is from the improper use of Nitrogen. Neither people had PRVs.

Neither person knew what they were doing nor how nitro assist worked.

Now, if a client even is considering Nitrogen Assist. I literally make them outfit every single chamber including the material columns with pressure gauge and prv. Every single spot that nitrogen can travel threw and settle needs pressure gauges and prvs. NO if and or buts about it.


Holy crap!!!

Glad u showed this to ppl … Makes me happy my prvs are 150 and 110!!!

Holy crap Batman!


Flat bottoms on a pressure tank are generally a no-no for design, same with vacuum.


Prvs mean pressure relief valve correct? When I run I do soaks, which means I let the solvent over run through the material as slow as possible until it starts to drip into collection base and then let sit and then I come back and do a pull through with my recovery pump, since now that I’m adding nitrogen, I will do the pull through with the nitrogen not the recovery pump?

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yes that is correct.
when you use n2 to assist your injection simply top off your cold solvent tank with between 15-60 psi of n2 gas (your milage will vary) and open the valves and inject. No soak is necessary, just let her wide open. After you have completed inject you can burp the n2 gas from your COLD solvent collection pot.If your collection isn’t dry ice cold you will loose butane.After the n2 gas is gone from the system recover like normal.