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What about fridge compressors?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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What about fridge compressors?

Unread postAuthor: RedAplle » Sun Sep 07, 2008 8:01 pm

Hi there,

I was just wondering, what happens when the limit of a fridge compressor is reached?

Because I have one, I have been up to 30bar (about 430PSI) with it, but I'm scary about how I'll know when I'm at the max pressure the compressor can up to?

Thanks, and sorry for my poor english =/
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Unread postAuthor: far_cry » Sun Sep 07, 2008 8:22 pm

some one have fridge compressor
he say that at 600psi tart to slow down
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Unread postAuthor: RedAplle » Sun Sep 07, 2008 8:27 pm

Thanks for the answer, so it will stop at its max pressure?
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Unread postAuthor: TurboSuper » Sun Sep 07, 2008 8:40 pm

I imagine it will get to a certain point where the motor just won't be able to drive the piston anymore.
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Unread postAuthor: Gippeto » Sun Sep 07, 2008 10:02 pm

It will start to slow down as the work required to generate the pressure gets closer to the output of the motor.

If you let it actually stall the motor, you will probably over heat the windings, and destroy the motor.
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Unread postAuthor: jimmy101 » Mon Sep 08, 2008 3:40 pm

Actually, the motor may or may not stall, no way to tell without a lot more info.

The maximimum pressure of any piston based pump is related to the compression ratio of the cylinder. A 10:1 compression ratio would be limited to about 150 PSIG at the outlet. That's neglecting heating affects. GasEq would give an estimate of the maximum pressure based on the compression ratio with the change in temperature of the gases taken into account.

If the motor can supply sufficient force the pump won't stall, it'll just quit adding air to the high pressure side.
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Unread postAuthor: man_o_brass » Mon Sep 08, 2008 5:02 pm

While I've never tinkered with a refrigerator, automotive AC systems are designed to operate under 250 psi. I wouldn't imagine a refrigerator to run any higher than an AC system, so 430 psi is probably well over what the compressor was designed to handle. Pressure systems are designed with a factor of safety built in, however, and are built to handle more pressure than they'll experience under normal operation. The problem is that, without knowing the factor of safety used, there's no way to know just how much pressure the thing will hold. Just because you hit 430 before doesn't mean that the compressor won't fail the next time you try. I'd keep it under 300 psi (20 bar).
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Unread postAuthor: VH_man » Mon Sep 08, 2008 5:05 pm

but 400 is sooo much fun! :D

honestly, i say that the motor will stall. thats what happens with most pumps. Just stop at 400, if it can get there. plus, 400 is PLENTY powerful.... you have to admit that.
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Unread postAuthor: man_o_brass » Mon Sep 08, 2008 5:18 pm

VH_man wrote:but 400 is sooo much fun! :D


Yes, I'm sure it is, but it's also not something the compressor is designed to do. It's double the normal loading, and 100 psi over what would be considered a serious problem in an automotive system. Run whatever you like through the bloody thing, just don't come back here whining if you find yourself missing a hand.
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Unread postAuthor: RedAplle » Mon Sep 08, 2008 8:39 pm

I'm not going to limit myself at 300PSI lol, my new pneumatic is designed to shoot at +500PSI, and it will shoot at this pressure ahahah.

And thanks for the answers :)
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Unread postAuthor: iisthemuffin » Mon Sep 08, 2008 9:01 pm

Hey, i jsut got a fridge compressor. How did you wires yours? Mine has 4 wires.
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Unread postAuthor: CasinoVanart » Mon Sep 08, 2008 9:15 pm

man_o_brass wrote:
VH_man wrote:but 400 is sooo much fun! :D


Yes, I'm sure it is, but it's also not something the compressor is designed to do. It's double the normal loading, and 100 psi over what would be considered a serious problem in an automotive system. Run whatever you like through the bloody thing, just don't come back here whining if you find yourself missing a hand.


Can you kindly explain how one would get a hand blown off with a fridge compressor, my understanding is that they don't have a tank so to speak, so the actual potential energy stored in one at 500psi would be fudge all.
It's the tank your filling that you should be concerned about in my opinion.
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Unread postAuthor: ramses » Tue Sep 09, 2008 3:39 pm

TurboSuper wrote:I imagine it will get to a certain point where the motor just won't be able to drive the piston anymore.


Actually, I think they are scroll pumps

CasinoVanart wrote:...Can you kindly explain how one would get a hand blown off with a fridge compressor, my understanding is that they don't have a tank so to speak, so the actual potential energy stored in one at 500psi would be fudge all.
It's the tank your filling that you should be concerned about in my opinion.


I agree, but make sure you use a check valve between the compressor and tank. otherwise the probability of loosing a hand will be greater.
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Unread postAuthor: Gippeto » Tue Sep 09, 2008 4:01 pm

Some of them are scroll pumps. Others ARE piston compressors. :)


http://s245.photobucket.com/albums/gg76 ... ompressor/
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Unread postAuthor: POLAND_SPUD » Thu Sep 11, 2008 12:49 am

there is one simple answer... all fridge compressors have a circut which is supposed to protect the motor from overheating or excesive load...

so most likely it will first slow down and then the circut will turn off the compressor
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