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I have wanted a vacuum pump for some time, but I refuse to pay the price for a new one that looks of sufficient strength and duty that I imagine I need.
I have read in different forums about the making of a vacuum pump from a fridge compressor, but with the mixed reviews I was reading I was a hesitant. I am glad I finely did. What a nice unit. I have not used it for any applications yet as I just completed the unit yesterday and have been testing it.
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In an attempt to produce more airflow (CFM) I broke this vacuum. I am glad I have started to find these for free. I tried to drill out the discharge to see if I could get more air flow. I have to say don't bother. The line inside is far more restricting and what a pain in the arse to fix, and still have it not work.
The new pump I found is not as good as this one, but should still work for my needs. I will be keeping my eye out for another.
If you are hunting for one look for a compressor with the starting capacitor like this first one. The only real difference between the two compressers I have is that the first had one and the new one does not, and the new one seems to have a hard time starting against the higher pressures.
I have read in different forums about the making of a vacuum pump from a fridge compressor, but with the mixed reviews I was reading I was a hesitant. I am glad I finely did. What a nice unit. I have not used it for any applications yet as I just completed the unit yesterday and have been testing it.
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In an attempt to produce more airflow (CFM) I broke this vacuum. I am glad I have started to find these for free. I tried to drill out the discharge to see if I could get more air flow. I have to say don't bother. The line inside is far more restricting and what a pain in the arse to fix, and still have it not work.
The new pump I found is not as good as this one, but should still work for my needs. I will be keeping my eye out for another.
If you are hunting for one look for a compressor with the starting capacitor like this first one. The only real difference between the two compressers I have is that the first had one and the new one does not, and the new one seems to have a hard time starting against the higher pressures.
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Signing UpStep 1Finding a Fridge Compressor
I found mine out back of a local Motel.
The unit is from a small bar fridge that is common in Motel rooms. Someone else had already removed the coil from the back so I could not scavenge that, but the coil and the coolant was gone.
Note: If the coil is still attached to the fridge there is a good chance that there may still be some pressure on the system, so be careful when cutting lines. There was also talk of oil spilling out of compressor, but mine did not spill oil, even when turned upside down.
I snipped the lines, leaving as much as possible, with a heavy set of side cutters I carry in the truck. The wires were cut as long as possible and the starting capacitor was unstrapped and saved.
What I needed besides was:
A power Switch w/face plate
Junction Box
Cord w/plug (junk TV I had)
Tennis ball ( with a few small scraps of rag)
Copper tubing
Vacuum gauge
Plastic tubing
Compressor Oil
Tools:
Soldering torch w/solder
Small pipe cutter
Screw Driver
Hot Glue gun
Large syringe
The unit is from a small bar fridge that is common in Motel rooms. Someone else had already removed the coil from the back so I could not scavenge that, but the coil and the coolant was gone.
Note: If the coil is still attached to the fridge there is a good chance that there may still be some pressure on the system, so be careful when cutting lines. There was also talk of oil spilling out of compressor, but mine did not spill oil, even when turned upside down.
I snipped the lines, leaving as much as possible, with a heavy set of side cutters I carry in the truck. The wires were cut as long as possible and the starting capacitor was unstrapped and saved.
What I needed besides was:
A power Switch w/face plate
Junction Box
Cord w/plug (junk TV I had)
Tennis ball ( with a few small scraps of rag)
Copper tubing
Vacuum gauge
Plastic tubing
Compressor Oil
Tools:
Soldering torch w/solder
Small pipe cutter
Screw Driver
Hot Glue gun
Large syringe
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I have managed to find an old deep freezer that still works with coils attached - Was wondering how to remove the coils?
As far as the capacitor goes the one already on your unit should be fine. And a check valve is always needed to separate the tank from the compressor. Otherwise the pump is too hard to rotate and may not start (trip breakers or stall).
When the compressor gets up to pressure (cut out) and shuts off, the line from the pump to the tank will bleed down its pressure through the pump allowing the pump to start easier.
I used to repair air compressors.
Of course there are losses. What could be the pressure achieved?? Would adding a third stage still improve the vacuum?
The unit I have gets to 28, which is -14 psi. The combination of units will only get you there faster and maybe a little past.
Internally, the motor rests on rubber grommets, so tipping it over onto its side usually trashes the compressor. ( the reason why fridges are only transported vertically )
However the main problem is that the refrigerant and oil mix which keeps the motor from burning out in its original setting, can no longer fulfill its function once the motor is hacked from the fridge.
Thus its lifespan is very limited.
A much better idea is to use a rotary piston compressor like that used in split system aircons.
These rotary piston types have an accumulator tank to store the oil and don't spray an oil mist over everything, also these pumps include a thermal cutout on top of the motor housing, and a plus factor is that the field coils/motor is welded to the casing, so no tip over problems.
I picked up mine at the scrapyard and it worked fine, I bought some compressor oil ( Reflo 68A ) from a specialist aircon supplier, and its been running sweetly for 4 years now.
I use a similar setup for vacuum bagging carbon regularly. To get the bulk of the air out I use a standard shop-vac. Pulls the mass of the air out in seconds.
As a reservoir, I use an old fire extinguisher. By adding two T-valves you can hook up both ends of the compressor to it and switch between pump and vacuum. Put the manometer and vacuumeter on the input of the valve otherwise you will pull a vacuum on the manometer, which will ruin it.
When using as a pump, add a filter to the vacuum side to prevent dust from entering. Dust will kill the pump very fast.
Use a mechanical timer to switch it on and off every 15 minutes. If you pulled a full vacuum and the system is otherwise sealed, this is enough to maintain the vacuum without over-heating.
Cheers