Compressed Air, Moisture & Critical Maintenance

Why maintenance is essential for productivity, energy efficiency and safety

Most of us are familiar with the old saying, ‘familiarity breeds contempt’.  The more often you see, use or do something, the less likely you are to treat it with respect.  Although in some areas of life this may not be important, in an industrial setting it will lead to practices that affect productivity, the reliability of equipment and the health and safety of employees.

The maintenance of compressed air systems is a case in point.  As the fourth industrial utility and with compressors, dryers, receivers and pipework all a familiar part of factory life, it’s too easy to take their operation, reliability and safety for granted.  Of course, most companies have rigorous maintenance procedures, with regular inspections being carried out by their own engineers or by third-party providers – often the company that carried out the original supply and fit. 

As time goes on, however, standards can start to slip.  Routine maintenance intervals become extended, while repairs are delayed or done as a temporary fix, which somehow never gets replaced.  Budgetary pressures, loss of skills and OPEX cuts haven’t helped; neither has the continued adoption by some companies of old-fashioned reactive or time-based maintenance procedures.

With the advent of predictive maintenance – these days improved by intelligent monitoring devices and, more recently, the introduction of AI – we’ve seen a significant improvement in the reliability and uptime of compressed air systems.   At the same time, with ever-more demanding production and process operations, as well as the introduction of specialized gas generation equipment, there is far greater emphasis on the need to produce the highest-purity compressed air and other gases.  The effect has been to raise awareness still further of the importance of effective and traceable maintenance of compressed air equipment, especially those ancillary devices such as dryers that are essential for optimum gas quality. 

Gas quality and moisture measurement 

Moisture in both liquid and gaseous forms is a major contaminant in compressed air systems, and is defined by the ISO 8573 standard.  Moisture can be drawn into the compressor as water vapor from the surrounding atmosphere, enter via leaks in pipework or equipment connections, and form as condensation due to changes in operating temperatures across each system.   

Whatever the source, moisture will lead to corrosion of internal metal surfaces, degrade the properties of lubricating oils and greases, and compromise the purity of compressed air being used for process or production duties.  Almost all compressed air systems will incorporate either a refrigerant or desiccant dryer to remove moisture in the air stream.  Under normal conditions, this should perform to specification; however, if it is incorrectly monitored or poorly maintained, the risk is that the exhaust air will carry a high moisture burden.  It’s also worth noting that maintenance failures elsewhere in the system can have an impact on dryer performance; for example, if compressors are running hot, the temperature of both the surrounding atmosphere and the discharge air will rise, increasing its capacity to retain moisture. 

This is where devices such as our Easidew EA2 Dew-Point Transmitter play a crucial role.  Installed in-line after a dryer unit, they provide extremely accurate real-time measurement of moisture levels, down to just a few ppm.  Similarly, our latest portable compressed gas dew-point meter, the Easidew PDP Dryer Portable, provides a quick, precise and cost-effective method of measuring moisture levels at critical points in each compressed air system.  The unit is lightweight, simple to use and self-contained, with a choice of data storage and connection options. 

These instruments are ideal for use in predictive maintenance regimes, providing a clear indication of changes over time in, for example, dryer performance.  This allows maintenance to be scheduled during quiet production periods. 

Dew-point sensor calibration

It is important to note that moisture measurement sensors and instruments also require regular maintenance.  The sensitivity and accuracy of sensors in particular changes over time, due to sensor corrosion or contamination and the longer-term aging of electronic components.  Recalibration is therefore essential, normally on an annual basis. 

To make this process straightforward we offer a Sensor Exchange Program, where a replacement dew-point transmitter is provided in advance, ready for swapping out.  The old sensor is returned to our calibration laboratory, where it is checked, adjusted and refurbished, ready for reuse.  It’s a quick and simple process that reduces downtime to a minimum. 

With 50 years’ experience in the development of moisture, humidity and dew-point technology, we are the application experts for all trace moisture measurement in compressed air and specialized gas applications. If you would like to discuss your requirements, please contact our team today. 

Did you know ?

The air we breath naturally contains water vapor.  The amount of vapor that can be absorbed by atmospheric air is largely determined by the temperature of the air; the higher the temperature, the greater the volume of moisture than can be absorbed.   

The maximum amount of moisture that can be absorbed at any given temperature is referred to as relative humidity, measured as a percentage.  When this reaches 100 %, moisture will begin to condense – known as the dew point. 

So, if the air surrounding a compressor – in the compressor room, for example, - is too hot, there is a risk that an increased volume of moisture will be drawn into the system, creating additional work for the dryer and using excess energy.  Air temperature will also rise as it is compressed.  Once air passes downstream it will cool and, depending on temperature and pressure, condensation will begin to form. 