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Condensate Is A Problem

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Compressor Created Condensate Is A Problem in the tank and in the air lines.

Condensate is a problem in your air lines, for all kinds of reasons. Free water and water vapor in your air lines could cost you a small fortune.

Thousands of dollars can be spent in maintenance to downstream air valves, air cylinders, air motors – all kinds of air operated actuators and equipment that are damaged by compressor created condensate and water vapor in your compressed air stream.

Run the air compressor long enough and there's a virtual waterfall in the compressor tank as the air cools!
Run the air compressor long enough and there’s a virtual waterfall in the compressor tank as the air cools!

Here are some of the problems and how they can affect your air, your air-lines, and the tools, valves and actuators that you use in your plant.


The air mains in your plant find themselves an ideal depository for the water vapor that condenses into free water as air flows through those air lines and air mains.

But, free water is not all that could end up in your air-lines and into your air tools, valves and cylinders as a result of the water created by compressing your air.

Rust In the Compressed Air

Are your air mains black pipe? Black pipe rusts in contact with water or water vapor! When that occurs, rust particles can break free from the walls of the black pipe and will travel along the mains in the air stream or with any water slurry. That air and liquid water can pour down your drop legs from the overhead mains, and slop into your air equipment.

That’s the main reason why you should plumb your drop legs from the top of the air mains. That will, at least, reduce the flow of liquid into the drop leg.

It is when your equipment has been idle for a while, and that rust slurry dries, that the problems really start as your valves stick, insides of your cylinder barrels score with the abrasive rust, and so on. Rust is a real problem created by water in your black pipe air mains.

Oil in the Air Lines

As your air compressor is working, the components that actually compress the air are often bathed in, or operate in, a bath of oil.

Despite the best efforts of air / oil separators lubricating oil gets into the tank and then the air line. If the compressor has seen significant use, older piston types in particular, the amount of oil that carries over to your compressor tank, and from there into your air lines, grows.

Unless your compressor is an oil-less type, meaning that in this type of compressor typically no oil contacts the compressed air, lubricating oil inside the compressor will inevitably make it onto the compressed tank and then into the lines.

What is the problem with compressor lubricating oil? We sometimes lubricate our air line components, don’t we?

Oil Additives in Compressor Lubricating Oil

The additive chemicals that are included in lubricating oil for compressors, are by and large negative to the Buna rubber type of seals found in most air line components. Compressor lubrication oil can dissolve the Buna seals, or, cause them to bloat, creating problems with the operation of the valves and cylinders and other equipment downstream from the compressor.

I expect that the lubricating oil manufacturers would love to have lubricant formula for compressors that was Buna-N and seal-safe. I suspect that that nature of the environment inside the compressor requires the seal-aggressive additives to be in the lubricant to allow it to function properly, and the absence of those additives would prevent good lubrication of the compressor moving parts. That would allow damage to the compressor, a cost problem of greater magnitude.

Crud Soup In Your Compressed Air?

Why is the water, and the other unwanted elements migrating into your air lines a problem?

The combination of water and the soup of contamination from the receiver, coupled with any contaminants in the main air lines (rust from the pipes / pipe dope, etc.) can send a slurry of crud down the air lines, possibly migrating through your air valves, to the actuators, or into your air tools.

When the equipment stops, and when the equipment cools, that crud dries out. It hardens into a varnish-like consistency that effectively slows or stops the operation of some of your control and actuator equipment. Next time you want to start the machine, some valves won’t shift or actuators won’t actuate.

Compressor Condensate Is Expensive!

The water and water vapor in compressed air costs you money in lost production, labor for maintenance staff to diagnose and resolve the problem, and wasted air equipment due to shortened life expectancy of components.

Even if it’s just straight water that’s moving down the lines, that water tends to wash out factory lubrication in the various air line components, hastening their demise!

You can’t stop your compressor from introducing gallons of water into the receiver. You can slow the compressor generated water from getting into your air lines. It is in your best interests to ensure that any water that does migrate to your lines from the receiver, gets taken out before it gets to air tools and other air driven equipment.

New comment? New question? Please add it here along with photos to help others help you with your compressor and equipment problem!

By Bill Wade

About Air Compressors has been helping folks with their Air Compressor Problems since 2002 online. We're a community of DIY and Compressed Air professionals who are keen to support everyone across the globe with their air compressor issues and troubleshooting. Whether you're trying to identify an old air compressor, or troubleshoot an error code on a sophisticated new industrial air compressor - the community at About-Air-Compressors.com is here to help you

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