Vacuum Pump - I Give In

[Fireengines]

I just received Curtis' Vacuum Chamber and hooked up my Harbor Freight 2.5 CFM Vacuum Pump that was recommended on his site. This pump is deadly! It emits a mist that I am sure is dangerous to breath my man and beast. Thinking there was a defect, I brought it back but the second one does the same thing. Now, I understand this is inherent to these machines. It is time to bring the thing back!

I've read a number of posts on this forum to purchase a refrigerator vacuum pump. My question is where do I purchase one and are there any instructions on using it?

It is time to come out of the mist!

 

[The Penguin]

my HF pump does the same.

try this. lift up on the exhaust cap. there's a little black cap inside there that I think you're supposed to remove. That helped with the mist some.

the other thing I've done is to place a blue shop towel over the exhaust while in use. It does a pretty good job catching the mist.

 

[Jim Burr]

Save yourself a ton of $$ and effort and get a refridge compressor at a appliance repair shop. Mine was $40 and pulls -28"hg in under 2 minutes and is dead quite
See it here; http://www.penturners.org/forum/f43/stabilizing-set-up-98564/

 

[Fireengines]

Jim..

How do you wire it?

 

[Gilrock]

I got the 3 CFM Harbor Freight Vacuum Pump and I've been happy with it. Isn't the mist you're seeing just the air/moisture that is being sucked from the chamber? It has to go somewhere. I see a light white mist coming from my exhaust but I never noticed a smell. I wonder if the 2.5 CFM version is that much different. Once I forgot to remove that black cap but it was kindly ejected across the room for me.

 

[MesquiteMan]

The mist you see is not dangerous. Vacuum pump oil is highly refined mineral oil. Granted, I don't want to have the mist in my shop either. That is why I spent the money and bought an American made pump. My JB Eliminator does not put out a mist at all but is is considerably more expensive. You get what you pay for in this case!

To do the refrigerator pump, simply get ahold of one. There are only 3 standard wires. A hot, a neutral, and a ground. wire in a plug and switch and turn it on. Put your finger over one of the copper lines. If it is sucking, that is the side to hook up the vac hose to. If not, check the other one.

The only problem I see with the refrigerator pump is that they will not last nearly as long. They are not designed for this purpose and eventually, the oil inside will become contaminated with moisture just like a regular vac pump will. The problem is, to my knowledge, you can not change the oil like you can with a regular vac pump and you will eventually start seeing a drop in vacuum as the oil becomes contaminated. They also will not pull as deep of a vacuum as a regular vac pump.

Look around at your local pawn shops. The professional HVAC technicians frequently pawn their pumps when the housing industry gets bad. Professional HVAC techs are not going to be using the cheap Asian imports like Harbor Freight so you should be able to get a good one at a good price. A friend of mine just bought a JB Eliminator from a pawn shop in San Antonio for $100. He brought it over and it was in good condition. Had to change the oil was all.

 

[Jim Burr]

It has the wires coming out of the relay Larry...two wires I think? I have a pic of that and will post it when I get home. The guy I bought it from showed me what was which...I suk at electrical!

 

[MesquiteMan]

I wonder if the 2.5 CFM version is that much different.

The 2.5 CFM pump is a single stage pump while the 3 CFM pump is a two stage pump. A two stage pump has a second "vacuum pump" in line that further pulls down the exhaust from the first pump, giving you a deeper vacuum. Not sure if it effects the oil mist, though.

 

[Jim Burr]

I checked with my HVAC guy about refridge pumps Curtis...he thinks they are great and have a really long life. His experience has been that they run a lot already, albeit in spurts which is harder on the motor than continued operation. I get -28"hg in under 2 minutes everytime I use it. I do need to ask the appliance guy I got it from about oiling...thanks for the reminder! Since I started with one, I'm going to log the run time on it and see how it does...could be a good comparison.

 

[MesquiteMan]

The only issue I see with refrigerator compressor pumps, Jim, is that you are not able to change the oil. I am sure they will run forever so not concerned there. However, as a refrigerator compressor, they are in a closed system constantly compressing freon. Moisture does not get in the system. As you get close to full vacuum, water will boil at room temperature. When that water boils, it becomes vapor and is pulled off by the vacuum pump. When that vapor hits the oil in the pump, it condenses back into water and starts to contaminate the oil. It will not kill a regular pump and most likely will not kill a refrig pump either. But as the oil gets contaminated with water, it looses its ability to create the seal that is its intended purpose. Remember, the oil in an oil filled pump is not just there as a lubricant. Actually, it is more to create a "temporary gasket" to create the vacuum.

With my pump, as soon as I start getting less than normal on the vacuum, I know it is time to change the oil. Frequently, when I do change the oil, the first good amount that comes out is straight water. Of course, I do a lot of testing of chambers filled with water so I expose my pumps to much more water than normally found during stabilizing so my oil gets contaminated more quickly. If you are always running oven dry (0% moisture) wood, then this should not be nearly the issue so the refrig pump may work great for a much longer period.

Also, your refrigerator pump is not pulling nearly as much vacuum as possible. If you are getting 28" Hg at your elevation, you are only pulling a 94.6% vacuum. Assuming you are 296' above sea level according to Wikipedia, your maximum theoretic vacuum is 29.596" Hg on a standard atmospheric day. I would expect that with a good quality vacuum pump, you should be able to pull 29.3 "Hg or a 99% vacuum easily. Now, will that extra 1.3" Hg make a difference? I don't know for sure but, remember, the definition of a perfect vacuum (for our purpose) is the absence of all air. You are removing 94% of the air where you could be removing 99% of the air, thus leaving more room in the material for more resin.

The bottom line, however, is that if you are getting the results you want, then your pump is working absolutely great for you and at a great price too! I actually recommend the refrig pump to folks who are wanting to save some money to get started.

 

[Jim Burr]

And that being said...that pump with your tank works great and I'm glad I did both!

 

[Gary Beasley]

I have one of those carbon vane vacuum pumps from a graphic arts contact printer. How well do these things work for this application?

 

[Mike D]

If the mist is bothersome then get a charcoal canister filter and attach it to the exhaust of the vacuum pump. When you see a drop in vacume just replace the filter.

 

[JD Combs Sr]

If the mist is bothersome then get a charcoal canister filter and attach it to the exhaust of the vacuum pump. When you see a drop in vacume just replace the filter.

That will work but there is also the type of demisting filter that filters out the oil and dumps it back into the pump. You don't have to change them. However, the caveat is that they are expensive.

 

[switch62]

You might find this video about the inside of a fridge compressor interesting Fridge Compressor Fun The Opening! - YouTube .

Looks like the oil inside is only for lubricating and cooling the motor only. As I understand refrigeration systems there is oil mixed in with the refrigerant (no longer freon) to lubricate that part of the system. As it is usually a sealed system there is no need to replace the oil.

So using this type of fridge compressor would expose the pump cylinders and piston to air and water and dry out any oil in them ? The pump would eventually die?

This has an explanation of the different types of compressors/vacuum pumps DIY Vacuum Pump - Repurposing refrigeration compressors - YouTube

TonyO

 

[CharlesJohnson]

I like the comment about the one stage and two stage vacuum pumps.The mention of The exhaust from #1 connects to suction Side of #2.I thought of this a couple of years back.Sents then I have seen it in videos and tutorials.At lest some older than that time period.Sure $40+$40 is getting a bit closs to some vacuum pumps.This one want be paying that much for refig. compressors.To many being thrown away.And I'm not bashfull asking for free throw aways.I also like the idea of the boost capacitor for quick restart. Have one left from before I retired.With things coming together so well I'm getting excited about making it. Thanks for this thread.Now all I have left is a cheap/free vacuum switch. And the "real biggy",Time.

 

[Fireengines]

I've corrected some of the mist by purchasing an auto oil filter (one that is not encased) and covered the hole.

 

[Fireengines]

Well today I used the vacuum pump along with Curtis' Vacuum Chamber. I let it run for about 30 minutes and came back and the vacuum gauge was full of oil and the Cactus Juice was ruined.
It is time to bring the thing back and start over again with something else.

 

[MesquiteMan]

Just to clarify Larry's post...I just spoke with him on the phone and there was no problem. I recently switched to liquid filled gauges and Larry did not catch that! All is well!

 

[Kretzky]

Just to clarify Larry's post...I just spoke with him on the phone and there was no problem. I recently switched to liquid filled gauges and Larry did not catch that! All is well!

Curtis, Just as a matter of interest, why are you using liquid filled gauges? We only used to spec those if the gauge was subject to excessive vibration or pulsing of the process medum.
David

 

[MesquiteMan]

Just to clarify Larry's post...I just spoke with him on the phone and there was no problem. I recently switched to liquid filled gauges and Larry did not catch that! All is well!

Curtis, Just as a matter of interest, why are you using liquid filled gauges? We only used to spec those if the gauge was subject to excessive vibration or pulsing of the process medum.
David

I am using them because the ones I now get are much better quality than the dry gauges I used to use. I now have a wholesale account and can buy them at a cost where I can offer them at the same price as the old, dry gauges. Also, I have had NUMEROUS problems with sticking dry gauges and had had to replace a number of them. The liquid filled gauges, since they are "lubricated", work much better without any sticking. The new gauges are stainless steel and are MUCH nicer gauges. I figured if I can buy them right and offer a much better gauge at the same price as the old gauges, I might as well!