Water Solutions ...3

This page continues providing information about removing water from compressed air systems. Page one on this topic is here.

If natural cooling of your compressed air does not resolve the water issues, and you have still got water dripping from your air valve exhaust ports and blowing through your air tool onto your work place, you have got to take it up a notch, in terms of air treatment.

Equipment Options

There are a number of pieces of equipment that you can purchase and install to cool and dry your compressed air.

I have listed ideas below, roughly in order of lower cost to higher cost. That cost might be reflected in higher purchase price, or higher operating costs, depending on the solution selected.


The first piece of equipment to consider is an aftercooler, a water jacket style, also known as a Shell & Tube type aftercooler.

This style uses cold water to remove heat from the air stream and to cool the compressed air, allowing moisture to condense out.

The compressed air from the discharge on the compressor flows into the after cooler and through one of a number of tubes inside the shell.

Outside the tubes, cold water is flowing throughout the shell, either in the same direction as the air flow in the inside pipe, or in the opposite direction depending on the brand and specifications.

As the warm, wet air from the compressor passes through the tubes, heat is radiated out of the compressed air, through the tube, and is removed by the cold water. Water condenses out of the compressed air stream as a result.

Water Jacket Aftercooler

One of the benefits of this type of compressed air cooling system is that it is low technology. Installation is non-complex, and it - overtly at least - does not consume energy to function.

In earlier times it was common to have water piped from the plant water supply into the water jacket, and out the other end to a sewer. Water was cheap and abundant.

Water Not Cheap Any More

However, water costs and sewage costs have put an end to that practice as companies are charged first for the water, and then again for the sewer costs for that volume of water.

As a consequence, and for good environmental reasons, the shell & tube type of cooler now normally recirculates the same water in an endless loop.

Thisrequires a pump, which uses energy, more complex control circuitry, and - depending on the temperature of the water as it exits the cooler, perhaps a cooling tower of some sort, all of which adds significantly to the equipment capital cost, and may - too - involve the consumption of higher levels and costs of energy to run.

A shell & tube type compressed air cooler starts out as being uncomplex and low-tech, but could grow quickly into a much more complex and expensive solution.

Refrigerant Air Dryer

Another post-receiver air cooler / dryer is a refrigerant system.

It functions similarly to your home refrigerator, with a compressor and cooling coils, but rather than pumping heat out of a closed box like happens with the fridge, the refrigerant air cooler funnels compressed air through cooling radiator(s) inside the dryer that decrease the temperature of the compressed air.

The refrigerant dryer lowers the temperature of the compressed air so that water vapor in the air condenses out where you want it to, and not in the air lines or air tools where you do not.

What You Need To Know

Things you'll need to know to get your refrigerant dryer sized are:
  • temperature of the compressed air entering the dryer
  • maximum flow of compressed air through the dryer
  • electrical supply voltage(s) available

The refrigerant dryer will provide a range of drying predicated on how much air going through it and at what temperature the compressed air is as it enters the cooling coils.

No Benefit To Under Sizing

If you undersize the refrigerant dryer - purchase a smaller model than necessary to save up-front costs - you will find that the unit cannot provide the compressed air cooling needed, and you undermine the purpose of the unit in the first place. Money saved here will cost you in the maintenance of and the replacement of air using components downstream.

It is important to ensure accuracy in sizing the unit, or err on the side of caution and oversize the dryer a bit. The downside of getting an oversized refrigerant dryer is the cost goes up, both in terms of purchase and operating the unit.

Still An Aftercooler

It is quite possible that there will still need to be a compressed air aftercooler - such as a shell & tube style - installed before the refrigerant dryer. In high demand air applications the air temperature coming to the refrigerant dryer from the compressor would be too high for the dryer capacity without pre-cooling the air.

Remember, conditioning or treating compressed air is a continuum. You will need to add additional equipment to bring the plant air supply to a level of dryness needed by the equipment you are powering with compressed air.

Another form of dryer used where the air application demands it, is the desiccant dryer. Please find information on it here.