Liquid water in compressed-air systems can lead to rusted equipment and unresponsive controls. Anyone who uses compressed air will, at some
point, find liquid water in the air distribution system. This can be anything from a nuisance to a serious problem, depending on the
application. If water might corrode equipment or introduce bacteria, removing it is critical.
Compressed air typically contains water as both liquid and vapor. Because removing it carries a cost, it’s important to define how dry the
air must be for a given application and specify the right equipment to produce this result. First, though, it’s helpful to understand the
source of water in a system.
Why and how do we dry compressed air?
Atmospheric air contains more water vapor at high temperatures and less at lower temperatures. This has an effect on the water concentration
when the air is compressed. For example, a compressor with a working pressure of 7 bar and a capacity of 200 l/s that compresses air at 20˚C
with a relative humidity of 80% will release 10 liters/hour of water in the compressed air line. Problems and disturbances can occur due to
water precipitation in the pipes and connected equipment. To avoid this, the compressed air must be dried.
What is pressure dew point?
The term "pressure dew point" (PDP) is used to describe the water content in the compressed air. It is the temperature at which water vapor
condenses into water at the current working pressure. Low PDP values indicate small amounts of water vapor in the compressed air.
It is important to remember that atmospheric dew point can not be compared with PDP when comparing different dryers. For example, a PDP of
+2˚C at 7 bar is equivalent to –23˚C at atmospheric pressure. To use a filter to remove moisture (lower the dew point) does not work. This
is because further cooling leads to continued precipitation of condensation water.
You can select the main type of drying equipment based on the pressure dew point. When taking cost into account, the lower the dew point
required, the higher the investment and operating costs for air drying. Five techniques exist for removing the moisture from compressed air:
cooling plus separation, over-compression, membranes, absorption and adsorption drying.
How to dispose of the condensate after drying the air?
Anyone who runs a compressed air system (using oil-injected technology) needs to be aware of how to properly dispose of the condensate in a
responsible manner, so as not to infringe any environmental laws. The condensate released by compressed air equipment will have tiny
particles of oil in that are not visible to the naked eye, which is why it needs proper disposal. Not only is incorrect disposal detrimental
to the environment, but you could also incur a fine and damage to your reputation as a responsible company.
There are many rules concerning the disposal of waste generally, as you will no doubt be aware if you have paid a recent visit to your local
recycling centre and compared that to a visit only a few years ago. Don’t let your compressed air supply catch you out without doing a
fairly easy first check.
Have a walk around your compressed air equipment: you should be able to see the condensate drains appearing from the back of the compressors
and dryers on your site. Take a look at where these are piped to. Ideally you should see them all going to an oil/water separator of some
description and then off to a foul drain. If they are going straight from a drain onto the floor or just into a standard plastic container
then this should raise a red flag. Oil/water separators are very easy to install. Note that there are many rules around the disposal of
condensate, even with the correct equipment in place, and the rules can vary from region to region.
Talk to New Zealand's compressed air experts:
If you are having issues with your compressed air system, don't hesitate to get in touch with the team at Ash Air. With coverage over all
regions throughout the country, over 100 staff, and hundreds of years of combined experience, you can count on us to deliver second-to-none
service and sustainable solutions that increase customer productivity.
Who we are and how Ash Air can help your business!
Ash Air has been around in New Zealand since 1979, and we’ve grown into a nationwide company with international support and a
reputation for quality and reliability.We look after all things compressed air for your business!
Reciprocating, Screw, air compressors
An extensive line of air treatment components
Ash Air's range of Chicago Pneumatic, Alup, Pneumatech, and Quincy compressors are used extensively around the world in industries
ranging from oil and gas to food, automotive and farming, and we bring you these world class compressors here in the land of the long white
cloud.Our technicians are compressed air equipment experts and are dedicated to addressing customer needs. Supported by a 13 locations
nationwide, Ash Air offers one of the widest selections of compressed air equipment and parts available today in New Zealand.
Reliability and Efficiency
With Ash Air compressors, you can count on reliability and high performance for even the most demanding applications. We focus our
efforts on the following:
Your company purchased an air dryer for your compressor, now where should you install it? One of the most common things we see in the
industry are air dryers being stored on top of the compressors. Seems like a wasted space not being used on top of the compressor, right?
Compressed air plays a fundamental role in industrial activities. Depending on the type of application, the energy cost of producing
compressed air can be very high. Below are some tips to save on you compressor bill.