What is the safest water PSI Range for lab glass condensers?

I thought I would open this thread because I searched for an answer and didn’t see one for something like this but I think it should be discussed.

I recently thought to myself about the PSI Ratings for condensers inside glassware like standard lab condensers, condensers for rotary evaporators, condensers on WFE Units and so forth. I never thought about the PSI rating of them until I looked at one of my water hoses and read the Max PSI Rating and it got me thinking : What is the safest PSI Range for lab glass condensers?

I of course don’t know this answer but I would love to know the answer.



just keep your expansion open to air and you won’t make bursting pressure

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The chiller for my rotary evaporator runs at 45psi


Found this
“The real pressure ratings depend on the wall thickness of the piece and the temperature as well. Most standard lab glass products, at room temperature, can take pressure up to 25-30 PSI. Also, be sure there are no scratches in the glass, as they will weaken the piece, which could cause it to break under pressure. Some glass vessels have very little or NO pressure rating. Most flasks or beakers are 5-15 psi maximum.”

but honestly I doubt the condensers are seeing much pressure over the head pressure because they are open on both ends.


15-30 general or higher


We have almost 60 psi of water pressure in our roto columns (city water pressure is crazy where we’re at) and no trouble yet but it’s worth noting that liquid pressure is much safer than gas phase pressure. If a coil cracks with water pressure, because it’s largely incompressible there won’t be much stored energy so the worst will pretty much just be replacing the glassware. When it happens with gas though, there’s a shitload more stored energy and that’s where the getting hurt happens. Personally, I wouldn’t run over 15psig with unrated glass


@SidViscous would you need a water pressure regulator on both the intake and out take if you wanted to go lower than 60psi?

I’d like to point out most vessels will never ever see pressure. Forceable inlet pressure out of a heater/chiller is rated if you stop the flow dead on.

Supply side pressures vary bc the outlet is always open and sending back and system isn’t exactly closed with positive tandem pumping.

The biggest issue isn’t exactly psi it’s turbulent flow. Some devices like coils or jackets all have varied amount of turbulence it can produce in flow and a varied amount it can handle.

A good reference is a large 50-100 liter reactor has at or above 30 psi in fluids through out so to speak by the time the bottom valve is measured with all the weight. I’m not exact but even then larger vessels can handle more flow rates even at mild psi. It’s the flow rate you Wana watch out for.

Small devices aren’t nearly as crazy as like larger long ass roto coils. That can be sketch based on manufacturer as well as lengths. The amount of fluid turbulence generally is what pops those. They should never be under high amounts of pressure wife the outlet is open. That’s one of the reasons why you also feed from top instead of from bottom. You avoid massive pressure spikes and inherently uneeded upward turbulence.


We have them running off the building chilled water which is pressurized by city water pressure, so we’d need a pressure reducing regulator on the inlet, a pump on the outlet to overcome the pressure at the return, and a check valve to hold back the pressure from the return when the pump is off. Kind of a pain, honestly I’m just working on replacing all our glass condensers with stainless


Let’s say you have a pump that only pumps water at 60 psi but you’re trying to lower the flow significantly you’d use a globe valve not a needle valve right?

Either could be appropriate, there wouldn’t be a substantial difference. As long as you don’t have a closed system the pump won’t actually build 60 psi because the other side will be open to atmosphere.

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I run a pretty big water pump through my coils. I was worried at first, used a smaller pump, but after using the bigger one for a bit I feel 100% confident in it. I believe the pump im using now is 1100 gph. (Dunno the psi). But it works amazingly well pushing water up both coils.