R-134a Oil question

[jwny]

I made an silent air compressor using a fridge compressor. It works very good. However, the compressor may pump some oil into the air line. I think to add some oil into the compressor. I know the compressor uses R134a oil. But I don't know what kind of R134a to use. Can anyone give me some advice for the oil? I attach an image to show what kind of compressor is.

Thanks!

 

[nehog]

You need an oil recirculator on that type of compressor. These are devices that strip the oil from the air, and feed it back into the compressor's intake.

 

[rburke65]

Wow....ya learn something every day on this site.

 

[jwny]

You need an oil recirculator on that type of compressor. These are devices that strip the oil from the air, and feed it back into the compressor's intake.

The problem is the oil come out of air filter may mix with water. In stead of reusing these oil, I am thinking of adding some oil. It is simple solution. And the oil is not expensive.

 

[Hammer1963]

You need Pag Oil. It should be available at most auto parts stores. Be carefull and do not overfill. The general rule of thumb is to add .5 oz for each tube over 1' in length and 1 oz for a condensor

 

[jwny]

Wow....ya learn something every day on this site.

The compressor works very well. It is very quiet. The noise level is just same as a small fridge. I attach more images to show the compressor.

 

[jwny]

You need Pag Oil. It should be available at most auto parts stores. Be carefull and do not overfill. The general rule of thumb is to add .5 oz for each tube over 1' in length and 1 oz for a condensor

I understand. Should I choose PAG 46, 100?

 

[T-Mac]

my son converted the a/c compressor on his jeep into an air pump to feed a tank in the rear of it-he just added an auto oiler at the intake pipe to the compressor-works well-nice to have compressed air that you can drive anywhere.
To answer your question it depends on the environment its going to be in-46 is thinner than 100-colder environment-thinner oil-hotter-thicker oil-100 is considered medium viscosity-good one size fits all

 

[stikman56]

Yeah, I'd think that the 100 would be good.

 

[jwny]

Ok. Thank you all for your help! I am going to get a bottle of PAG100.

 

[75gmck25]

Was the compressor ever used with any other type of refrigerant? R-12 systems in cars used different oil, and when you retrofit one to R-134a it is common to use mineral oil instead of PAG because PAG and the remaining old R-12 oil don't work well together. However, if it was always an R-134a system or has it has been fully cleaned and flushed, then PAG works best.

Bruce

 

[rlitman]

You need Pag Oil.

I would beg to disagree. He's compressing AIR, not R134a. Air carries moisture, and PAG oil will lead to failure.

You want to flush the compressor out completely of any PAG oil, and then fill for AIR use with mineral oil.

 

[jwny]

Was the compressor ever used with any other type of refrigerant? R-12 systems in cars used different oil, and when you retrofit one to R-134a it is common to use mineral oil instead of PAG because PAG and the remaining old R-12 oil don't work well together. However, if it was always an R-134a system or has it has been fully cleaned and flushed, then PAG works best.

Bruce

It is aways R-134a oil. On the left upper corner of the compressor label, it states that it uses R-134a. It is brand new from a wine cooler.

 

[pop pop]

I would beg to disagree. He's compressing AIR, not R134a. Air carries moisture, and PAG oil will lead to failure.

You want to flush the compressor out completely of any PAG oil, and then fill for AIR use with mineral oil.

This!

 

[38Chevy454]

It does not matter that the compressor was set up for R-134a, you are not compressing R-134a - you are compressing air. I think almost any oil will work for your application, the key being that you need to have a constant small amount of oil to keep the compressor from burning up. Ideally you want an oil that will not oxidize, and can be recycled. I think mineral oil would meet these reqts.

 

[kbs2244]

With all due respect to the pros, I think this may boil down to a duty cycle question.

I had a scrap refrigerator compressor that I used as an air compressor for over 10 years.
It blew into a 20 lb propane tank with a bunch of DIY plumbing.
Typical suburban use. Bike and car tires, and such.
I wasn’t painting or sand blasting anything.
I did nothing to "condition" the incoming air.
It never failed. Whatever oil was in the sump worked fine.

I replaced it with a DIY compressor made from a 1963 Plymouth AC unit only because my mother totaled the Plymouth.
That unit, a "V 2," is still running fine, after 40 years of the same duty cycle, with "raw" air intake and only the oil in the sump when I removed it.
And the same basic DIY plumbing.

IMHO those refrigerator compressors are one of the most over built pieces in modern appliances.
How many millions are out there and are replaced only because the shade of green they are in is out of style?

 

[atty5420]

With all due respect to the pros, I think this may boil down to a duty cycle question.
How many millions are out there and are replaced only because the shade of green they are in is out of style?

I understand what you're saying, but in all likelihood that compressor is loaded with Mineral Oil. I agree, wholeheartedly, with 38Chevy. PAG oils are highly hygroscopic. They will grab moisture in a heartbeat, ultimately leading to a milky mess which will spell a quick doom for the compressor. As has been pointed out, a compressor is a compressor. Use the oil adapted for the application. In this case, it is without question, a Mineral based oil, which couldn't care less about grabbing a bunch of moisture for refrigeration reasons.

JWNY, I realize your thought process is to match the oil to what's on the label, BUT that's for refrigeration, specifically using 134a. That is NOT what you're going to be pumping. You are going to be pumping moisture-ladened air which is the kiss of death for PAG oils. Please flush all traces of PAG out of the compressor and use ONLY Mineral based oils. To go a step further, I recommend synthetic oils, but that's your call. Do NOT use an oil that ***** moisture out of the air like a magnet, a la PAG.

 

[chris142]

Ester ?

 

[38Chevy454]

Ester ?

Otherwise known as POE, which is also R-134a compatible. Might work, but why buy that more expensive when cheap mineral oil will work? Even motor oil will likely work for this application, that will be cheap as you get. Does not need much.

 

[jwny]

TO atty5420

Thanks for your input! I have a couple of questions.

1. If I try to flush P134a oil out the compressor, I don’t think I can completely clean the compressor inside out. There will be some of oil left in the compressor. So, is P134a compatible with mineral oil?

2. Can I use mineral oil sold at local drug store, such as Walmart, Walgreens, etc?

 

[sberry]

Use common compressor oil, that's what I think they mean when they say mineral.

 

[JRC3]

The compressor works very well. It is very quiet. The noise level is just same as a small fridge. I attach more images to show the compressor.

You have my attention. LOL

So what's the recharge time or cfm on something like this? If I'm just shooting 18ga and 15ga nails, how would it keep up? What about a framing nail gun?

 

[jwny]

You have my attention. LOL

So what's the recharge time or cfm on something like this? If I'm just shooting 18ga and 15ga nails, how would it keep up? What about a framing nail gun?

No. I am not shooting nails at all. It is for my DIY air bearing tonearm to play vinyl records. I have no knowledge of compressor oils. This is why I posted questions here.

Here are a couple of pictures to show the air bearing tonearm.

If the mineral oil is not the one I mentioned in my previous post, someone please direct me to some sources to buy it.

 

[JRC3]

No. I am not shooting nails at all.

I was just curious if a setup like in the pics you posted could be used for nail guns.

 

[T-Mac]

wow!now I know why you need a quiet compressor!

 

[rlitman]

I was just curious if a setup like in the pics you posted could be used for nail guns.

Yeah, probably, though the CFM is going to be VERY low.

If the mineral oil is not the one I mentioned in my previous post, someone please direct me to some sources to buy it.

Compressor oil would be a non-detergent oil, such as ND-30. Any auto place will have it. Or you could step up to something fully synthetic such as Mobil 1 5W30, if it will be in a cold place like your garage.

 

[jwny]

I did a search and found the oil (Please see the image)on zoro tools website.

http://www.zoro.com/i/G2382642/

I guess it should be ok.

 

[atty5420]

JWNY

To answer your previous question, no....you won't be able to get all of the PAG out of the compressor on the first flush, so do it again. I'd use a cheapo compressor oil on the first run and then synthetic after that, but you do want to get as much of the PAG as possible out on the first flush. Then monitor the color after that. I wouldn't be adverse to two flushes, if you can handle it. All oils have a high residual, so it may take a few flushes to get home. Remember this stuff has coated all the walls of itself as well as the tubing it was running through.

It's not like you have to get every molecule out, but the more PAG that is left, the more moisture you are going to accumulate in the oil. Give it as many oil changes as you can afford. That's why I suggested that you start with a cheap compressor oil first.

 

[nehog]

OK, but one thing to keep in mind, is that that type of compressor is designed to recirculate oil, so you'll always have some oil coming out the high pressure side, and will have to ensure that you replace that oil with new. This is why no one uses this type of compressor for making air...

 

[rlitman]

This is why no one uses this type of compressor for making air...

Not no one. Scroll compressors which have the same oil blow by issue are quite popular in the 15 up to several hundred horsepower range.

Buy a filter/lubricator set. Plumb the lubricator onto the compressor input, and the filter on the output. The coalescing water filter will also do a decent job of pulling the fog of oil mist out of the air, and the lubricator will keep the compressor running. Adjust the lubricator so that it runs out of oil around the same time that the filter is full.

If you're really creative, you could plumb the drain of the filter into the bowl of the lubricator with a needle valve that allows some oil to return on its own.

 

[jwny]

Hello all!

It has been a great learning experience. I am going to try to flush the oil out of the compressor first. I guess it is not easy to do it. It may take a lot of patient to finish it.

To rlitman,

It is a great idea to put the oil back into the compressor by using a lubricator. I will definitely check it out. I have no idea how the lubricator works so far and am going to find it out.

Thank you all!

 

[LS6 Tommy]

The second biggest issue after oil entrailment with using a refrigeration compressor for compressing air is they're designed to be cooled by refrigerant vapor. It doesn't happen too often so it's not really a big issue, but if you run one long enough you can overheat it.

Tommy

 

[Worsedog]

No. I am not shooting nails at all. It is for my DIY air bearing tonearm to play vinyl records. I have no knowledge of compressor oils. This is why I posted questions here.

Here are a couple of pictures to show the air bearing tonearm.

If the mineral oil is not the one I mentioned in my previous post, someone please direct me to some sources to buy it.

Now THAT"S a record player!

 

[jwny]

The second biggest issue after oil entrailment with using a refrigeration compressor for compressing air is they're designed to be cooled by refrigerant vapor. It doesn't happen too often so it's not really a big issue, but if you run one long enough you can overheat it.

Tommy

I installed three computer cpu cooling fans. The compressor runs about 30 mins then it stops for about 30 mins. It continues to supply compressed air to the tonearm even when the motor is not running because it has large air reservoir(10 gallons tank). The highest temperature of the running motor is 105 F. Most of times, it gets about 100 F. But once the motor stops, it will be cooled down to 69 F and lower. The down side is that fans generate some noise.