Things that don't compress well, like moisture and particulates. Compressors are designed to compress and move gas not solids.

 

Compressors are designed to pump(move a vapor).

Air is considered a non condesable, as it doesn't condesne into a liquid in the refrigerant circuit.

 

Things that don't compress well, like moisture and particulates. Compressors are designed to compress and move gas not solids.

Millerman, with all due respect, you've missed the mark.
Maybe you are describing "non-compressables" ?
Solids can't compress, but they are already about as condensed as anything can get.
Moisture can't be classified as non-condensable, because obviously, it will condense.

A non-condensable, as applied to refrigeration, is any vapor that will not condense into a liquid at pressures and temperatures normally found in a refrigeration system.

The most common non-condensable is air, or one of it's major components, nitrogen.
Having air in a system negatively impacts efficiency, and ultimately, shortens the life of a system.
Air just takes up space, and is circulated through the system, and adds nothing to the cooling ability of the system.
It costs money to pump, with no benefit.

Non-condensables can be removed with a vacuum pump, before charging the system with refrigerant.
If the system already has a mixture of refrigerant and air, then the refrigerant should be replaced, along with any filter-drier.

That's my two cents worth.

 

I have read about systems being contaminated by "non condensables" due to poor installation. What exactly are "non condensables"?

Along with the good replies you've already received, the question you may wish to ask is what the significance of "non condensables" are.

Remember Dalton's Law of partial pressures, the law that states the total pressure within a vessel is the sum of all individual pressures of all gases within the vessel? Non condensables figure into this law.

Take two identical units with identical heat loads running side by side on the same day at the same time. One system was evacuated and dehydrated properly at installation and the other was a blow n' go (no nitro purge, no vacuum pulled). Which unit will have the higher head pressure? Obviously the blow n' go unit. Non condensables in the system also means there's less room in the condenser for the refrigerant condensing into a liquid to reject heat from the space where it picked up that heat.

Another factor is compression ratio. With non condensables present, the compressor must work harder to build head pressure, resulting in a higher compression ratio, and another loss of efficiency.

With moisture as one of the non condensables, the penalties to the system are not limited to the higher compression ratios and a less efficient condenser. Moisture degrades compressor oil and over time may form acids in the system, which eat away at compressor motor windings. On low temp systems, moisture may freeze in the metering device.

 

non condenserabl

any thing in a ac system that will not make a change in state. from a gas to a liquid or a liquid to a gas.

regards,
Kelvin

 

noncondensibles

Why installing ac you could get air , oil , moisture in the lines.That is nocondensble.All sorts of problem then.

 

Re: noncondensibles

Why installing ac you could get air , oil , moisture in the lines.That is nocondensble.All sorts of problem then.

How do you get oil in the lines?

How do you get it out?

Moisture is NOT a non-condensable.
Neither is oil.

 

Re: Re: noncondensibles

Why installing ac you could get air , oil , moisture in the lines.That is nocondensble.All sorts of problem then.

How do you get oil in the lines?

How do you get it out?

Moisture is NOT a non-condensable.
Neither is oil.

Exactly, moisture is sometimes confused with non-condensables because it is present in air, which is the major non-condensable seen in systems. Moisture causes it's problems by other methods, ie corrosion, sludge formation, acid formation, iced up metering devices, etc.

 

Regardless of what noncondensables are you dont want none of the mentioned items in the refrig system they all have there own special little problems they cause.