Refrigerator Compressor as a Vacuum Pump

General Composites Discussions Equipment Talk
#1

I have LOVED this idea and done a lot of research on it, and feel it’s best for me as my workings with composites is a hobby and I do it in my basement.

So, I got lucky (I think) and picked up a brand new compressor that was delivered to a consumer accidentally and the company said just keep it.

My problem?? I’ve got no clue how to wire the dang thing up. I’ve got a run capicator with it as well as a overload protector, but how do I set everything up?? I presume I could somehow try to connect directly to the three pin connectors coming off the compressor and bypass everything, but I’d like some level of protection.

Initially I want to just run it hot off a plug, and later down the road once I’m past tinkering I will be adding in a vacuum switch, ect.

Anyone care to lend some wiring advice??? I’m normally not this inept but I’ve NEVER wired refrigerator internals before.

Thanks!

#2

Do not use the 3 pin connector in that manner! Bang!

Google the model number, find a wiring diagram :slight_smile:

#3

Found the diagram, and wow. I looked at it, looked at the capacitor and overload connector, noticed that the capacitor actually fits directly ON the overload connector, leaving me tow connections left. I thought “No, it couldn’t be THAT simple.”

Just found an old light to cut the cord off of and do a test. Sure enough, it’s that simple. Everything is installed as it should be, just a couple of female spade connectors to fit on the overload connectors. All I need to do is get the stuff to make a grounded cord and I’m in business. Little bugger pulls some vacuum too if my finger has anything to say about it.

Thanks for the help Malcolm. I couldn’t figure out which on the part number was but managed to weed through a TON of info on the manufacturers website to get it figured out. Glad I didn’t try direct connecting to the three pins. :smiley:

#4

Me too, would’ve been impressive :smiley:

I’ve a mate who would know how to wire it up, if you like, draw a wiring diagram and snap some pictures and I’ll get him to double check your work / make safety suggestions.

#5

I could be dead wrong here, BUT… don’t those fridge compressors come with a relay that shuts them off and on? Just thinking out loud here because that type of relay that cycles the compressor on and off would be of no use for the type of work we use pumps for.

Again I’m no expert on pumps :slight_smile:

#6

I’ve used a fridge pump for a couple years on and off. My results have been good.

A couple issues.

Firstly, the fridge pump is lubricated by oils carried by the vaporized refrigerant. Since it’s no longer being used in a closed circuit sense, it is no longer getting it’s RDA of lubrication. Eventually, it’s gonna burn out. But in the meantime, it’ll pull some pretty good vacuum. But then again, it was meant to push, not pull, so it’s having to work harder to do something it’s not quite meant to.

Because most fridge compressors don’t have a check valve, you either need to install one of your own, or cycle it constantly to get the levels of vac you want.

Next, for big parts/projects, you have to pull vacuum for a long time. Because of the lubricant issue above, and because these compressors are designed to be cycled, you are going to get the compressor good and hot, and eventually you’ll burn the oil, and from there, it starts to wear out.

Like I said above, I’ve been using mine for a couple years, it’s made a few dozen parts for me, and at this point, to pull a decent vac, it’s too hot to touch, but it still works. Eventually, it’ll lose efficiency to the point of no longer functioning…when I’ll move on to another compressor.

#7

Nope, they’ll run forever if you let them… that’s what the vac switch is for (through a relay of course, don’t let the startup current run through the poor switch!).

#8

Use a vacuum switch, it’ll take decades before it gets to a point where you can measure any degradation. You could of course put a little more oil in it if it were to run low… but really it’s not worth it. Basically it’ll run down to a point of somewhat equilibrium and then lose it at a minor rate, which is why they last so long as vacuum pumps. Of course there’s a number of assumptions and generalizations in those statements, there are just so many different types and models.

#9

Tis funny. My experience with pumps like this (granted, it was from an AC, but same idea, and it WAS a large AC), it only worked several times, spit oil, and eventually just gave up trying to work. Maybe I was trying to run it open too much (this was for a N2 laser system, so it wasn’t a fully sealed system until the end of testing), so maybe that is why it died on me.

NOW, my AC industry vacuum pump, I’ve hated since the beginning…over heating, smoking, spitting oil out the exhaust, so many random bits and knobs. oi! People love them too.

I just don’t have luck with anything but expensive ones meant for composite work :slight_smile:

#10

The only common denominator is you :wink: :smiley:

#11

Having done some research on the oiling issue, I’ve found a common theme: Set up a catch tank or elevate the compression line to where the oil won’t make it out and will drain back in. The idea I liked the best was the one where the guy attached a copper tube and coiled it spiraling upwards, allowing plenty of travel for the air/oil to separate and for the oil to drain back.

#12

Yep, then stick a ping pong ball over the end :slight_smile:

#13

hey great to see you using this site as a resource!
good luck with the projects

#14

Well, I just hooked it up to a bag for the first time. Dang. That’s all I can say.

I am using a thick piece of lexan for a base, with an A/C vent panel out of a car as a test piece. This thing pulled enough vacuum to actually WARP the molded plastic panel and bend the mounting tabs over. I’d say it works. :smiley:

Time for a vacuum regulator I’d say.

This site is great. I’m learning quite a lot, even though this is just a hobby/side thing for me I want to do it as right as I can.

#15

no, you want to support the piece you are doing, because you WANT a full vacuum!!!
A roughing pump can warp a stainless steel bowl too…

#16

I actually had it supported by the lexan. I was only laminating the top layer of the piece, so it was getting the full brunt of the vacuum. I shut it off this morning so hopefully it was cured enough after 7 hours in the vacuum with it being 64° in my basement.

#17

Oh boy!!! I think I found a setup that works!!! Have a look!

The same but “New” pump setup:

Controlling the Vacuum: An air compressor regulator for bleed control, two barb fittings, and a small three way manifold. Total cost: $20

Vacuum monitoring: Simple automotive vacuum gauge on a plastic “T” fitting plumbed AFTER the bleeder valve:

And you get this, with a steady regulated vacuum on the item. No excessive forces, a very nice 20 in/hg of vacuum. My pump ran up to 30 in/hg before I cut it off on a test. QUITE happy.

Now I just need to switch to a more pliable film that will stretch better and not leave pleats. Hopefully this is the last time I try this piece.

Now, I do realize that the way I have this bagged is completely improper, I’m just experimenting with ways to get the best finish. This is just a “play” piece that I’ve probably bagged and stripped 5 times now. I didn’t like the release film finish at all because it left too thin a layer of expoy, so I’m trying just a solid film here to get a smooth finish, but this one has pleats so it’s time to move to the green bagging material that stretches better.

What do you guys think?? I have a grand total of $100 invested in this setup currently.

#18

Thanks for the write up, it makes for good reading.

The only comment I have is to avoid using those type of hose clips, they deform the pipe and don’t provide a uniform seal. Try using Minaba or double eared O rings for a better job. The DEOR just need a pair of carpenters pincers to tighten them.

I’m looking forward to seeing this work. :slight_smile:

#19

it looks good to me, this is the sort of set up i was thinking of for mine. See the

http://compositeforum.werksberg.com/showthread.php?t=3355

thread.

Any chance of some more detailed picturs of the set up. Ie laid out from one end to the other in a line, and or pictures of the set up of the compressor?

#20

How quiet or loud is that fridge pump? As a reference the average car puts out around 85db of noise.