how do air-line filters work??

[POLAND_SPUD]

the title speaks for itself...
I want to build an air filter for a fridge compressor... its main aim is to remove oil that comes out of a fridge compressor from air

does any one have any idea how they work ?

buying a commercial air filter is not an option because they are rated to 10 - 18 bar max

I am thinking of something that could be housed inside a 0.75 - 1.5" T

Edited by jrrdw.

[ralphd]

If you what you an oil separator that can handle high pressure then you want one designed for air conditioning. It is a cylinder that the discharge line from the compressor is connected to(usually from the top) then exits(usually the top as well) on its way to the condenser coil. In the cylinder the heavier oil leaves the flow of refrigerant as it changes direction. The oil fills the chamber then a float opens and the oil is pushed back to the sump of the compressor. There are many designs. Here is a link to one...

http://www.henrytech.com/Tips/HT-TT4.pdf

On the bigger Trane systems the compressor is connected to the condenser coil's header directly. The header of the coil is much bigger and the oil collects at the bottom where a resovoir is made. A line is run to an external float assembly connected directly to the compressor itself. You can do it this way but rather finding a float use a ball valve and open it briefly once in a while while the compressor is running.

Have you tried harbor freight?

[spudtyrrant]

hvac guy ftw!!!!!!

[Mr.Sandman]

My guess is that it is some sort of cellulose material with big enough cells for decent airflow, but small enough to stop oil particles. besides, why would you want to keep the oil out? i find that it helps maintain my coaxial's sealing face. I remember seeing this one page where the guy rolled up a tissue inside a metal tube and stuck it on the compressor. Not sure how well it worked.

[POLAND_SPUD]

thx ralphd
harbor freight is not an option for me... shipping would cost too much


so you are saying that even something as simple as what you can see in my drawing will work ??

if I understand you correctly there are two possibilities here (well.. actually 3 ):
-add some sort of helix to force air to rotate around the smaller tube, which will centrifugally separate oil
-add some sort of screening material, like wire mesh or stuff used in air intake filters for cars
- mix the two ideas

the biggest advantage of centrifugal oil seperator is higher flow, right ? would I really need it on a fridge compressor ?

[Mr.Sandman]

I think that would work except make it a 3 stage filtering process. by having two filters instead of one you can be sure that at least 80% of the oil has been filtered out of the air.

[spudtyrrant]

that should work fine poland.
good idea with the ball valve i would empty it after every fill tho just to make sure you don't get any oil in your cannon or airgungun.

[Mr.Sandman]

that should work fine poland.
good idea with the ball valve i would empty it after every fill tho just to make sure you don't get any oil in your cannon or airgungun.

You now having some oil in air cannon is a very good thing. it helps clean the residue from it and lubes your barrel and sealing face.

[rp181]

You can just bubble the air through water. S in your drawing, the clean air out would be input, the bottom red part replaced with a end cap, and filled with water to the .5" tee.

[spudtyrrant]

that should work fine poland.
good idea with the ball valve i would empty it after every fill tho just to make sure you don't get any oil in your cannon or airgungun.

You now having some oil in air cannon is a very good thing. it helps clean the residue from it and lubes your barrel and sealing face.

yeah but i would rather regulate the amount of oil i have in my air cannon

[Mr.Sandman]

that should work fine poland.
good idea with the ball valve i would empty it after every fill tho just to make sure you don't get any oil in your cannon or airgungun.

You now having some oil in air cannon is a very good thing. it helps clean the residue from it and lubes your barrel and sealing face.

yeah but i would rather regulate the amount of oil i have in my air cannon

Exactly i meant having some oil in your gun. Having an oil bog in your chamber wouldnt be good now would it?

[POLAND_SPUD]

@mr sandman
yeah I think that oil is good for cannons... it prevents rusting, helps in sealing and it lubricates parts... I don't want to completely eliminate oil (I don't need it to be 99% efficient) even 70% would be enough

you know when you use the compressor quite often and the volume of air it pumped is really high there is quite a lot of oil condensated inside air hoses, vales etc.
every now and then you get a few droplets leaking out with air through pilot valves... I've got oil stains everywhere

ohh and don't forget about environmental impact of oil

[ralphd]

As long as the other end of the ballvalve is hooked to the crank that will work.....just don't forget to open the ball valve once in a while.

[POLAND_SPUD]

what do you mean by crank? the crankshaft on the compressor ?

well if that's what you meant I am afraid it might not be the best idea because it could remove some water from air apart form oil only

while it doesn't seem like a big deal in a sealed system (refrigeration) I suppose it's a really bad thing to do on an air compressor

I imagine that after a few weeks or months of using it might separate several litres of water

[jimmy101]

It really depends on just how much $$$, just how well you need it to work and just how much oil is actually in the air stream.

If you just want most of the oil out of the air stream, and there isn't all that much to begin with, then you can just blow it through wire mesh. Occasionally you remove the mesh and clean r repalce it. Something like coarse steel wool would work well for the mesh. Just lightly pack the mesh inside of a tube. I've also seen several layers of say 1/16" grid hardware cloth used as an oil trap.

Bubling through water isn't going to work well at high flow rates, you won't catch much oil and you'll saturate the air with water, heck you'll get greater than 100% water saturation in the air stream because of fine droplets that form as the air exits the water.