Do you have a refrigerator compressor?

GrantR

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Does anyone have a refrigerator or freezer compressor laying around? I am looking for any type of a/c compressor to build a vacuum pump. I saw a few homemade ones on you tube using refrigerator compressors. Compressor needs to work.
 

Lee Scatt

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Hi Grant, Are you doing some a/c service or are you vacuum bagging? I have 3or 4 nice Kinney pumps you can use if needed.
The old frigidaire pancake compressor is the one you want, if you want to make one up.
When the newer compressors run under vacuum for awhile, they will cut off on thermal overload due to the lack of cooling gas flowing thru.
 

StanFoster

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Grant- If you are wanting a constant vacuum.... I have never used one...but at woodshows, they sell a venturi type device that just needs a low steady flow of air through it....and the result is a very powerful vacuum. They would demonstrate using a 1 x 12 board being vacuumed down on the bench, and you could sit on the board hanging off the bench. The most you can vacuum of course is just over 14 pounds per square inch...but that is some serious clamping pressure. If I did vacuum bagging, I would have one. If I recall correctly, it was only $30 or so.

Stan
 

Gyro28866

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On Hermetically sealed compressors, the electric windings on the motor are cooled from the returning refridgerant (gas). If you hold this unit for an extended run in a vacuum, it will fuse the windings from overheating; unless there is a thermal overload protection circuit build into it. Eventually it will fail also.
It can get bulky; but an automotive a/c compressor, driven by an electric motor or gasoline engine can provide a decent vacuum.
I have even tied to the intake on my AIR COMPRESSOR and pulled some pretty deep vacuums.
I built a unit one time, to suck up liquids. I tapped into the intake on my pick up trucks engine, ( engine running at idle will provide the greatest vacuum) and run a line to a 300 gallon tank in the truck bed. I had a 90 degree ball valve at the tank end. on the other end of the tank I installed another ball valve, and a reenforced hose for sucking oil up. Start the engine open the valve to the tank and draw a vacuum into the tank. then open the other valve and suck oil up real quick. This method is used by several local port-a-potty vendors.
 

gyroplanes

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My friends Subaru pickup (30 yrs old) drew enough vacuum to collapse the 55 gallon drum he was sucking oil into. Very powerful manifold vacuum.
 

Rehan K.Janjua

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Besides all the problems and hick-ups of hermetic sealed compressors the most serious
issue is lubrication oil........which has to be fed from the suction line.

These kind of compressors will work as long as it is lubricated.

Tom has the best option and its absolute vacuum the highest.

Good Luck.
Rehan
 

gyromike

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Grant- If you are wanting a constant vacuum.... I have never used one...but at woodshows, they sell a venturi type device that just needs a low steady flow of air through it....and the result is a very powerful vacuum. They would demonstrate using a 1 x 12 board being vacuumed down on the bench, and you could sit on the board hanging off the bench. The most you can vacuum of course is just over 14 pounds per square inch...but that is some serious clamping pressure. If I did vacuum bagging, I would have one. If I recall correctly, it was only $30 or so.

Stan
I have a couple of the venturi types made by Air-Vac. They can be ordered right from the website.

I think I have the AVR062H. They work well and I use the regulator on the compressor to limit air flow while still pulling a decent vacuum.

 

Monte55

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Does anyone have a refrigerator or freezer compressor laying around? I am looking for any type of a/c compressor to build a vacuum pump. I saw a few homemade ones on you tube using refrigerator compressors. Compressor needs to work.
First question....what do you want the vacuum pump to do? What will you use it for?
 

GrantR

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I want to built a icyball adsorption cooler using methanol/ activted carbon. I need to create a good vacuum in the cooler so the methanol will evaporate at a low temp. I may try acetone but I dont know if it will adsorb into anything.
 

dinoa

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Acetylene readily dissolves in acetone. Check out its heat of adsorption if its enough for your needs. It also auto detonates at higher pressures than those found in acetylene tanks.

You cant beat the ammonia/ water adsorption refrigeration cycle though.

Dino
 

Gyro28866

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Grant:
A vacuum is a volume of space that is essentially empty of matter.
keep in mind that when you start and you look at the gauge which you are using. It is displaying a pressure of "0" which is actually the current atmospheric pressure (inside and outside the vessel) being displayed like an altimeter. On a pressure gauge you do not have a Collsman window like an altimeter, to dial in the pressure differential compared to 29.92"hg. When you pull a vacuum on a refridgeration system, you are actually removing (matter) contaminates, like oxygen, nitrogen, water (in vapor form), etc. It is better to pull a vacuum slowly to remove these contaminates. If you pull a vacuum quickly, the water vapor will evaporate and turn to ice and freeze to the container wall. Then the gas which you use as a refridgerant will be contaminated and can cause the gasses evaporation process to be hindered. A 1 to 2 cubic feet/ minute rate will work well for "moving" the contaminates out of the system. your local AWOS or FBO is a source for the current Barrometric pressure.
Example: If you are under a high pressure system and the current barometer pressure is 30.5"hg then subtract 29.92 from this to see a callibration differential of .58"hg.
I hope this makes a little sense for you.
I have never used Methanol as a refridgerant, most absorbtion refridgerators use ammonia for a pressure-equalizing fluid, butane as refrigerant, and water as an absorbing fluid.
Sorry, I got caught up in the moment...
Depending on how critical the vacuum (removal of matter) is, you might need to use a "vacuum pump" designed for operating to the lower pressures. Talk to your local HVAC guy and borrow his pump. Tell him what you are doing and he will most likely want to help, if nothing else just to see if "this thing" will work.
Good luck

ps:
most household vacuum cleaners are only about 20% effecient. The intake on a vehicle is maybe 45% efficient.. nowhere near enough to do what you want.
 
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