oil free compressors

[majavan]

dear sirs\madams

i would like to know about the mechanisem of oil free compressors and which type of compressor could be oil free and why oil free compressor used in some gas industries for example in injection or gathering.

best regards.

 

[butelja]

Typical oil free compressors are multistage centrifugal or oil free screw. The centrifugals last longer and are priced accordingly. Some manufacturers of the centrifugal units include Cooper Turbo (Joy), Gardner Denver, Atlas Copco, and Elliott.

Oil free compressors are used where you don't want oil to get into the process stream.

 

[macetransit]

I know of some oil free compressors/vacuum that use graphite vanes in a rotary hub. They are self-lubricating because of the graphite. These are on the small side, fractional horse power.Try this comp.

http://www.gastmfg.com

 

[SPLIT]

Atlas Copco manufactures oil free screw compressors.They compete with the centrifugals

 

[quark]

There are reciprocating oil free compressors also. Graphited teflon is used as MOC for piston and guide rings. Lubrication is provided to the crank shaft and connecting rods but the oil is restricted to enter into the cylinder by packing rings. Ingersoll Rand and Chicago Pneumatic manufacture these compressors. You can get them in single and multistages also.

If you have direct contact of air with your product (like some pharmaceutical applications)better use oil free compressors. (oil free means your air is oil free but not the compressor)

 

[dugal]

There are air compressors such as rotary screw type that some people believe to be oil free. If the compressor bearings are oil lubricated due to the high RPM's alls it take is for an internal shaft seal to fail and you end up with oil in your system. Not a lot of oil, but traces.

 

[AlanMelia]

My experience of oil free compressors are typically used for pumping oxygen to make breathing mixes for divers.

Typically a rubber diaphragm is used to prevent oil contamination which would be, and has proved catastrophic as hydrocarbons and pure oxygen do not mix well. But this still requires oil in the compressor for cooling and lubrication.

 

[Ezra]

I hope this helps.

Some manufacturers in an attempt to "catch" business market oil-free compressors as oil less. However there is a "remarkable" difference, oil free compressors carry oil for lubrication of the prime mover and oil less compressors carry none what so ever. In oil - free compressors sometimes there is carry over of the lubricating oil, requiring the compressor to have either a reclaimer or oil separator before air entry to service air. These compressors may be of the centrigugal (using vanes for example Broomwade's Hydrovane, which uses a series of seven or eight small vanes in an elliptical rotating assembly to compress air for service; reciprocating, where there is a high pressure and low pressure side of pistons, here the pistons have two sets of seals air seals to the top of the cylinders and oil seals at the bottom of the piston to ensure that lubricating oil from the crank case does not get into the air side; with the rotary screw, you will see that the lubricating oil from the screw is "captured" using something called a reclaimer which essentially acts as an oil filter, some argue that the screws are far more efficient than piston type compressors.

In the oil less compressors which are primarily used in medical applications and also where there is the possibillity that the hyrocarbons in the oil, high temperatures and certain gases, for example oxygen are present in large quantities that it may pose an explosive hazard. The compressors use no oil and are in most cases piston type. In this case the piston seals are made of graphite and provide lubrication for the pistons this way. There are a few companies I know of who manufacture this type of compressor see JUN AIR compressors online at

http://www.junair.com