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Cleaning IPA

I have seen other people post about making a “still” to clean the used IPA. So I tried it with a pressure cooker and a coil of copper pipe in a cooler for the condenser.

Well that attempt worked but was very slow. And if you used to much heat the IPA would boil and run dirty IPA into the condenser. It also was very slow and not be worth the time.

So I had an idea to use a vacuum pump to see if it would speed things up. First attempt I put the pump pulling the vapor from the pressure cooker. That made the pump get very hot so I moved the pump to pull from the condenser. That worked pretty good, still not fast but it may be worth it. What happens is pulling the vacuum keeps the IPA from boiling and it keeps all hoses and the pressure cooker lid tightly sealed. So basically you use a lot of heat on the pressure cooker and that speeds things up.

I did not measure the speed or timing yet but will do so next time. What was left over in the pressure cooker was a thick molasses. I had been doing clear and black resin. I need to find a way to clean that out of the pressure cooker.

A professional solution takes about 2~3 hours for 10 liters. I read you didn’t measure it you but state it took too long so how many hours approximately?

A vacuum on top is only needed for higher temperature boiling solvents (such as TPM) as IPA boils at a lower temperature than water.

Pro solutions use special bags (they need to survive high temperatures) that retain all the impurities after the recycling and then you just remove the bag and throw it away with any cleaning need.

Also be careful with home made solutions (and cheap ones) due to all the dangers involved.

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I was thinking of some plastic bags. Just need to find what will standup to IPA and heat. The vacuum pump lets me keep the heat on without it boiling the dirty IPA into the condenser. My guess is I get 1.5 liter or more in one hour.

Doesn’t the vacuum pump mean the boiling temperature of the IPA is reduced, so you don’t need heat?

I guess it depends on what you call vacuum. I have an refrigeration pump that goes down to 200Torr or so. That causes any moisture in the refrigeration system to evaporate at room temperature.

A.

I would guess the boiling temp is reduced. My vacuum pump is a Thomas 107CAB18-H which is a diaphragm type pump that does not need oil. It only pulls 23 inches. I would guess it would work without heat but that would provide very slow results. What I find is I can keep the heat on full and it does not spit out dirty resin. So it really speeds up the results with the high heat. Don’t know if the IPA will damage the pump diaphragm yet.