Best Pumps For Moving Cold Liquid

[OCme]

Here is good link for elastomers and what they are capeable of:


http://www.gmt-international.com/Elastomer%20info.htm

check out silicone it's good down to -70C

[Calab]

Originally posted by OCme
Try finding out what type of elastomer is being used in the pumps that you research....I know members that are using these Danner Mag pumps with no problems down to -40C, which may mean that they are using a perbunan elastomer like the Ehimes. I'm beginning to get the feeling that many of the top water cooling pumps are using this elastomer, but I don't know for sure....If this is the case we need to be researching other pumps like the fuel pump sky mentioned, or the taco pump which is an all metal pump, or maybe the surflo.

i specifically asked what the material of the elastomer was. to not be so impersonal, unlike the a-hole on the receiving end, i thought i would mention the application, so they would know why i was trying to get more information.

after getting his second uninformed and useless reply, i felt compelled to rub in that Danner Supremes are being used in -30c and below environments 24/7 and next time he should have half a sense of what he is talking about.

before i decided to contact danner, i looked into the tacos as well. their site has all the pertinent information people look for when picking pumps, so i moved on to the next manufacturer i wanted to know more about.

the real problem i see with taco are they are behemoths compared to eheim and the likes. even the small pumps are a good 8 pounds and make no attempt to be compact. these are engineered for the application extremists would be using it in, but i don't think the tradeoff is worth it. but i place more of an emphasize on aesthetics over performance. no way would i have a 8 pound block of cast iron sitting in my loop. but that's just me.

[OCme]

Originally posted by Calab
the real problem i see with taco are they are behemoths compared to eheim and the likes. even the small pumps are a good 8 pounds and make no attempt to be compact. these are engineered for the application extremists would be using it in, but i don't think the tradeoff is worth it. but i place more of an emphasize on aesthetics over performance. no way would i have a 8 pound block of cast iron sitting in my loop. but that's just me.

You can keep your pretty boy pumps; if it doesn’t serve its intended purpose then what good is it? I for one would rather have a 20lb pump that would move -70C liquid than an aesthetically pleasing one that could only do -30C. Just think of the possibilities a -70C pump would open up in regard to a cascade or auto cascade chiller. I guess the question is do you want a show pony or a work horse?

[OCme]

Perhaps Taco isn't the best pump either, we are exploring new possibilities here, and there are many, many, many more that can be researched.

[Lotec25]

i dont see a problem with the taco pumps either. Yea there heavy but who cares. It's going to be set off to the side anyway. The only problem i see is the plastic on the Circulator it needs to me made out of a hard metal that will not chip if for some reason a piece of ice gets pushed threw it. Or maybe a screen over one side of the inlets to keep the ice out. I am sure there is a pump out there that will work below -50 maybe even -100 the problem is finding something that can either keep out ice or something that will push it threw. maybe increasing diamater for the hose from 1/2 inch to bigger will take care of this problem but you still have the block to contend with. A piece of ice is not going to flow threw one of the blocks.

Lotec25

[Gary Lloyd]

Aside from the surface of the evaporator itself, the most likely spot for ice formation is at the eye of the pump impellor. In other words, if ice is going to form, it will form inside the pump.

[Lotec25]

ok that makes since. So now we know one place to work on. We dont want to heat it that would just be a waste. So how do we stop it, or how do we break the ice up will the impeller break the ice without causing it alot of harm? I think we need to look at gear drivin pumps for this. If ice was to form on the inside of the pump the magnet will be the first thing to go. Ill keep working on it. I know i am finding problems and no answers yet. I am looking at it as if we need to solve the problems that could occur and then fix them that will point us in the right direction.

Lotec25

[Calab]

Originally posted by OCme
You can keep your pretty boy pumps; if it doesn’t serve its intended purpose then what good is it?

i'm doing this for fun. i'm not trying to achieve that absolute lowest possible temperature. so the pumps i am interested in do serve it's purpose.

[Gary Lloyd]

We dont want to heat it that would just be a waste.

That may in fact be the best solution. It wouldn't take much heat, just enough to warm the inlet to a safe temp.

There should be no ice formation. If there is ice, the mixture is not strong enough. And yes, ice can destroy the impellor.

[OCme]

Originally posted by Gary Lloyd
That may in fact be the best solution. It wouldn't take much heat, just enough to warm the inlet to a safe temp.

How about running a pump in a seperate bath slightly warmer than what the chiller is chilling to to keep it from freezing?

[OCme]

Food For Thought:

I was thinking, it would not be hard to mod a pump with a silicone elastomer that could do -70C. It would probably void the warranty, but if you ended up with a pump that could move colder liquid then it would defiantly be worth it. Elastomers are very inexpensive and come in many sizes. Just a thought.

[Gary Lloyd]

Both good ideas, and definitely worth considering. Voiding warranties is what OCing is all about.

[kingsack]

If you are runbing sub -40C then you will probably be using pure alcohol, most likely methanol or isopropanol. If that is the case then the best thing to do is use a water trap in your resevoir. This is done by inserting a smaller container in the expansion area of your resevoir and then piping air in and out. Your very cold liquid will keep this small container cold enough that any water vapor will condense out in the trap. This should keep your system slush ball free for many moons. I would include a screen of some kind in the pump inlet. A witches hat (a cone shaped screen) inserted backwards would do nicely. This will work the best if you are running your pump submerged in your resevoir.
If need be I can draw a picture easily and email it to interested individuals.

[OCme]

So far the best pump I can find for moving liquid in the -40C / -50C range seems to be a seal-less mag drive pump. This would eliminate the possibility of the elastomer failing and ruining the pump. The best elastomers are silicone or flurosilicone which I found out is good down to -73C. The best mag drive pump bearing choices are silicone carbide or ceramic.

Here is a link to just such a pump which might be the Holy-Grail to many...

http://www.pondliner.com/PondmasterPumps.htm

[OCme]

I spoke to a mechanical engineer today that knew a lot about thermal dynamics and pumps. He said that there are pumps that will move -70C fluids. He recommended that the pump be made of stainless steel, brass, or aluminum ( Aluminum @ sub zero temps is 2X stronger than steel), and the pump would need to be seal-less. So if you are building a cascade or autocascade chiller and you need an xtreme pump these are the kinds of pumps to be looking at.