Is your compressed air dryer fit for this summer?

The atmospheric air drawn into a compressor is a mixture of gases that always contains water vapour. However, the amount of water vapour that air can carry varies and is mostly dependent on temperature. As air temperature rises during compression – such as in the warmer summer months that we are now approaching – the air’s ability to hold moisture (or water) also increases. When the air is then cooled its capacity to hold moisture reduces, which causes the water vapour to condense. This condensate is then removed in the centrifugal separator, or the air receiver, downstream from the compressor. Even then, the air can still be completely saturated with water vapour. This is why, as the air cools further, significant amounts of condensate can accumulate in the air distribution piping and at take-off points. System failure, production downtime and costly service and repair work are all unavoidable without sufficient air drying.

Temperature and pressure affect the water content in air. Therefore compressed air dryers are generally rated to achieve a certain volume of air flow and specific moisture level. Due to this relationship, dryers have correction factors. This information is usually supplied by the manufacturer, and helps determine which compressed air dryer size is right for specific conditions. As a result, the size of the dryer will impact how well it operates in its ambient surroundings. So, when you size up a compressed air dryer, it is important to consider what the ambient temperature might reach during peak summer.

Yes, the location of the compressed air system can also impact the performance of the dryer. It stands to reason that the cooler the air is going into the compressor, the lower the dryer inlet temperature will be. The effectiveness of the dryer may be improved by installing it in a cooler location.

Condensate is an unavoidable result of air compression. Large quantities of condensate accumulate when air is densified in a compressor. For example, a compressor with a free air delivery of 5 m³/min (referred to 20^oC, 70% relative humidity and 1 bar absolute air pressure) pumps around 30 litres of water into the air networking during an eight hour working day!
20 litres of this water precipitates as condensate in the aftercooler (at 7 bar working pressure and +30^oC outlet temperature). During further cooling of the compressed air, the remaining 10 litres precipitates as condensate at any convenient point in the air network. This condensate is a chemically aggressive fluid that mainly consists of water, but also contains oil and dirt particles (e.g. rust). If not reliably drained off at all collection points, it can cause operational disruption and severely damage the compressed air system through corrosion.
There are however, a number of condensate drainage system options - from float drains to condensate drains with level-sensing control. 

Is your compressed air dryer fit for this summer? Aside from ensuring that your compressed air dryer is sized correctly, don’t forget the importance of having it serviced. Following the manufacturers prescribed maintenance scheduled will not only lower the maintenance requirements and associated costs, but it will also ensure your compressed air dryer is working correctly, efficiently and reliably, and is ready for those long hot summer days. 

Sources:
KAESER Kompressoren (2016): Compressed air engineering – basic principles, tips and suggestions
KAESER Talks Shop Blog, Camber M. (20 May 2015): The art of dryer sizing

Would you like some advice on your compressed air dryer(s)? Just phone 0800 447 820 or fill in the form below and we will contact with you.