Compressed Air Condensate and Its Disposal

Production facilities must deal with by-products from operating machinery and using raw materials. With air compressors, it’s common that moisture is produced due to the methods utilised in the production of compressed air.

Unfortunately, compressed air production is a sensitive process with excessive moisture, affecting the operational efficiency of the internal machinery, its ability to function long-term, amongst other factors.

In this article, we examine air condensate, how to manage it, and the associated legal aspects too.

Moisture in the Air

Compressors release condensate near the unit itself. This might look like H2O, but it’s not. It is water, combined with tiny parts of oil mixed in, and some particulate matter that’s too small for the human eye to see. This interesting concoction results from the compressor’s operation.

The air that is pulled in through and past the inlet valve into the compressor will naturally contain moisture from the air. We typically might refer to this as humidity, but the type and quality of ambient air near the inlet have an impact on the moisture levels after the compressor has completed its work.

Compressed air can happily contain water within it. That is, up to a certain point. This is referred to as the pressure dew point. Air will have a pressure dew point, but so do various gasses as well. They will each be unique. 

This point is the stage where water cannot be held within the air or gas, and it will become condensation. Alternatively, it will become a liquid, when there’s too much vapour, and it’s impossible for it to remain in its current state.

We admit it can get complicated here. However, it is referred to as compressibility. If you think of a sponge, it can hold water. But, there is a limit to how much water the sponge can contain beyond its natural weight. After that, it begins to leak water on the bathroom floor. And… so it is for air compressors, too.

For example, setting a compressor to 7 bar of pressure condenses air down to seven eights of its original volume. Because the same air now takes up less space, it has reduced its water-holding capability by the same amount. Therefore, when compressing moist air, it will compress down successfully, but water will remain after the condensing process.

As a practical example of what we mean, about 84-86 litres of water result when a 100-kilowatt air compressor pulls in air at 20 degrees Centigrade, with roughly 60% humidity levels and runs for roughly eight hours.

The more hot and humid air, such as in a tropical environment, the more compressor condensate is generated through the air condensing process. Indeed, in a highly humid environment, it is likely that a compressor could produce several hundred litres of water daily. Therefore, knowing this, arranging for it’s legal and safe collection is important.

Issues Caused by Too Much Moisture

Extracting additional moisture from an air compressor is always a good idea. Additional moisture causes problems inside the machine, but it also isn’t great externally either. Unwanted moisture contained within compressed air may affect the performance and functionality of valves, motors, and other components.

Furthermore, any manufacturing equipment benefiting from the compressed air may suffer, malfunction, or reduce lifecycle time, due to excess moisture, too.

While air compressor systems do vary, typically, you’ll want to see an aftercooler being used that both drops the air’s temperature lower, and cuts water levels. A water separator is also excellent and should be installed in many cases if one is not present. When chosen and sized appropriately, it separates water from air with over an eighty-five percent success rate.

An air receiver is next. The tank of the air receiver is at a much lower temperature than the air, which can act as a separator too. Other processes include a wet tank that collects additional moisture and requires periodic draining as part of the regular maintenance to keep it in a better condition.

Therefore, as you can tell, there is a multi-level process to removing water from hot, condensed air.  

Managing Condensate to Stay Within UK Law

Environmental awareness affects everyone, and businesses are no exception either. Existing laws in the UK are robust, but newer, tougher ones come on the law books regularly.

Companies that use compressed air equipment, which relies on oil either injected or added through another process, need to make themselves aware of the correct way to dispose of condensate to stay within the law. Damage assessment costs and fines for improper disposal can occur when not following the rules. 

Also, with the ease of sharing negative news in the media, companies need to stay ahead of any PR issues by avoiding making such mistakes, rather than acting now and apologising later.

An initial review of the existing compressors by an appropriate, knowledgeable manager is never a bad idea. This should take in the state of the filters, wet air receivers, dryers, condensate drains in the rear, etc.

For oil-based compressors, it’s necessary for what’s being expelled to run through a process to remove any oil from the condensate. An oil/water separator is a useful inclusion and should be added if it’s not already present. These often have multiple processes to gradually remove all oil from the condensate, to make it safe to dispose of.

A discharge notice from the local water authority is necessary for permission to dispose of condensate that’s been properly processed. Once it’s clear of oil, the water needs to be directed to the foul water drainage system. A storm water drain or a standard rainwater drainage system is incorrect, and should not be used.

When reviewing the current installation, where drain water from the compressor system is either being collected in a plastic tub or is being allowed to leak onto the floor, this needs an immediate resolution to resolve the matter. Also, when no oil/water separator equipment is present, this should be added ASAP.

Lastly, local regulations vary from place to place, site to site. If you operate your business at multiple locations, it’s necessary to verify what permissions are required for discharging water at each location. This might come from a local water authority, or exemptions sought and obtained from the Environmental Agency, where appropriate. This needs to take place before more disposals occur.

Do You Need a Review of Your Installation?

Anglian Compressors have decades of experience in installing, maintaining, overhauling, and upgrading air compressors. If you’re unsure where your business stands, get in touch, we are happy to help.

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