Pneumatic systems & components

Remove water from factory air

Third Quarter 2021 Pneumatic systems & components

A leading cause of costly downtime and emergency maintenance is water vapour and the resulting condensed water that is trapped in factory compressed air.

Water in facility airlines can cause corrosion, rust and pipe scale, which can break loose to block or adhere to air passageways, and lead to increased pressure drop and loss in machine performance. Machine components will suffer premature wear and parts deterioration from water:

• Pneumatic cylinders will have their pre-lubricants washed away, corrode and respond slower.

• Solenoid valves’ rubber seals will stiffen and become more susceptible to rupturing and leaking.

• Instrumentation can malfunction even with the presence of only a small amount of moisture.

• Air powered tools will likely stick and perform less efficiently.

End products are also at risk of suffering quality deterioration because of water:

• Spray painting will be adversely affected by change in colour, adherence and finish quality.

• Industrial ink-jet printers will be adversely affected by change in adherence and finish quality.

• Blow moulding plastic bottles’ viscosity and material consistency could be adversely affected.

• Glueing/taping adhesiveness of cardboard boxes could be adversely affected.

• Pharmaceutical mixing and integrity could be adversely affected.

• Food processing may be contaminated because of micro-organism growth.

How does water vapour enter factory compressed air?

All atmospheric air contains contaminants and water vapour that is concentrated during the compression process. The heat generated during compression increases the capacity of the compressed air to hold moisture, thus avoiding condensation inside the compressor. Lubricants used to improve the efficiency and life of the compressor also become part of the contaminant load, as do wear particles.

A compressor with a 75 kW capacity, operating at 30°C ambient temperature, a relative humidity of 80%, compressing air to 7 bar, can produce approximately 113 litres of condensate during an eight-hour shift.

Removing liquefied water from factory compressed air


The compressed air exiting the compressor can reach temperatures as high as 150°C, which is unusable for industrial applications. This hot, saturated air will release 70-80% of its excess water vapour if simply cooled to near room temperatures. To achieve this type of cooling and bulk moisture removal, air- or water-cooled aftercoolers are often employed. Condensed liquid is removed from the aftercooler via automatic condensate drains.

The air exiting the aftercooler will still be saturated but at a much more manageable temperature. Because the air is at a dew point of 37°C or more, it is still vulnerable to further condensation into liquid water should it be exposed to temperatures lower than this dew point. The piping in most industrial facilities would allow for further temperature fluctuation, thereby allowing more condensation to take place as the air moves through the plant.

Drip legs

The next line of defence for removing the water is a drip leg. This is a vertical pipe plumbed at the air drop line (below the horizontal header pipe) to allow water to be drained away using the principle of rapid air expansion to condense water vapour into liquid water. The condensate is then removed by a drain at the bottom of the drip leg, which can be automatically or manually drained to avoid overflow of contaminants.

Water separators

Water separators use mechanical separation techniques to remove condensed water in bulk from factory air, either by directing inlet air into a spiral and using centrifugal force to separate the water out from the compressed air, or by passing the inlet air through a special resin filter element with large meshes to trap water particles that will drop down to a collection bowl allowing the compressed air to pass through.

SMC’s AMG Series water separator can remove water droplets (up to a 99% removal rate) using a special resin filter. It is easy to install and requires no electrical power.

Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

High performance hydraulic hose
Gates Pneumatic systems & components
Gates is a global manufacturer of innovative, highly engineered power transmission and fluid power solutions. The company has further expanded its PRO Series hydraulic hose portfolio with the launch of ...

How do you audit a compressed air system?
Artic Driers International Pneumatic systems & components
The British and American governments estimate that as much as 10% of all electricity generated is consumed by air compressors, and that some 50% of this energy is wasted. Air leaks alone can account for ...

Pneumatics and digital transformation: overcome what’s holding you back
Emerson Automation Solutions Editor's Choice Pneumatic systems & components
While IIoT offers the promise of a revolutionary impact on manufacturing, implementation of the technology has its challenges. What holds us back from a broader embrace of digital transformation, especially in pneumatics? And how do we move past the challenges to embrace the opportunity for real improvement in productivity and efficiency?

How smart pneumatics enhances machine safety and operation
Emerson Automation Solutions Editor's Choice Pneumatic systems & components
Pneumatics and safety Machine manufacturers and end-users have always used pneumatic devices to provide cost-effective and efficient motion and actuation on a wide range of systems; pneumatics has also ...

The ‘P’ in predictive maintenance represents progress, not pain
Editor's Choice Pneumatic systems & components
There are three main types of maintenance: reactive, preventative and predictive. But how do you make sense of these terms? Human health can provide an analogy to machine health. Take diabetes, for ...

Oil-free air for petrochemical pipelines
Pneumatic systems & components
Rand-Air recently took a bold decision which has changed the way its customers – and Rand Air – will approach future hires. Working in the petrochemical sector requires critical attention to detail, with ...

How to embrace the benefits of smart pneumatics
Emerson Automation Solutions Editor's Choice Pneumatic systems & components
Understand how this challenge creates opportunities It is important to consider how insights from data can help end-users react to real-time events or even predict the future. For example, the Emerson ...

New energy efficient, compact compressor range
Pneumatic systems & components
CompAir has launched a new series of energy-efficient oil-lubricated, rotary screw compressors, offering best-in-class performance in a compact design. Part of the CompAir L-Series range, the new compressors ...

Use compressed air efficiently
Artic Driers International Pneumatic systems & components
With air compressors being one of the bigger consumers of energy in many plants, it pays to keep tight control of compressor station power costs. Focus points include:    • Compressor performance testing. • ...

Digital transformation: how to embrace the benefits of smart pneumatics
Emerson Automation Solutions Pneumatic systems & components
For end-users responsible for maintaining machines and keeping them running, the path is clear. An IIoT system provides data from the machine, ensuring its systems or components are working within their ...