Hey all, I am looking to get a diaphragm pump that I can use to recirculate a vat of chilled liquid through a jacket. I would like this to be able to go down to dry ice bath temperatures. Any recommendations here? I can’t personally afford a chiller, especially one that reached -80°C, so I’m trying to figure out alternatives.
check it!
Diaphragm pumps dont like to work at really low temps, really you are limited by the material of the diaphragm. @cyclopath had been down this road for pumps, here were his choices.
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Are you going to be moving alcohol as a chiller fluid?
Check out the eco 633 or bigger. I’ve used them to make a chiller to flow alcohol through a jacket.
http://www.ecoplususa.com/shop/product/ecoplus-eco-fixed-flow-rate-submersible-pumps
They are magnetic impeller driven pumps and can easily move cold alcohol.
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Oh wow for real? Submergible in -70°C ethanol?
All day long. I’ve made a “chiller” with em. Guy who taught me a lot of what I know showed me ways back
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Holy shit man you’ve just made my whole fucking day 
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What sizing pump for what size jacket?
Absolutely, you’re very welcome. Are you going to be making a dry ice slurry with a “tank” in the middle with the pump in there, flowing fluid? Or something similar.
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I’m going for a dry ice slurry with the pump placed in a bucket within that which will hold the fluid to be circulated, then that leading to my jacketed recovery vessel I’m getting made rn.
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Pretty much same thing I was saying, ya. Don’t let the slurry get in there and bubble up. That’ll mess up the pump. If you can, put a lid with the hoses going in and out with the power cord. To keep it covered and anything else kept out.
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Got it, thank you for the tips. I will keep my pump in a 5 gal bucket and keep that in an ice chest filled with iso dry ice slurry. I’m trying to do a 24 hour crystalization.
Awesome! I’m stoked to know how it goes.
I have a Viton diaphragm pump 110v 60psi and it will not build pressure below -20ish. I have contacted the company that manufactures the pump and we are changing the viton for something that can handle the temps. The new diaphragm & gasket material can go down to -60c and still function.
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yeah, just don’t try and fly this in a regulated shop.
the reason this works is that one requires a source of ignition, vapor, and oxygen to have an issue, and at dry ice slurry temps you’ve got no vapor. you’ve also got no oxygen when submerged in ethanol, and assuming the seals designed for water also hold up to ethanol and remain elastic at -80C, there shouldn’t be access to ignition either.
Props to your mentor @Dred_pirate.
However, it’s still a non-compliant hack, and my biggest concern is that someone will decide it passes for food-grade too, and chuck one in their heptane denatured extraction solvent…
I have no clue on material compatibility for that trick.
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You have a point with mixing it with other than alcohol. I was wanting to mention that they obviously can’t move anything else really. They are a means to get by, is all.
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Holy hempsmoke dred pirate, I mean, aaarrrggggh.
Definitely going to try this asap
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it looks like your application doesn’t need alot of head feet of pumping, You may find a mag drive pump is more suitable for this application. Diaphragm pumps are a good tool, just not in the low temp ranges. You are mostly limited by the diaphragm material. You can find mag drive pumps in a all stainless build.
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Did you try out the ecoplus submersible pump yet for -80 slurry? I’m assuming you used some sort of isopropyl or ethanol for the slurry ?
Yes it works. Place the pump in a bath that is sitting in the slurry then have it pump through a coil also in the slurry
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