Estimated reading time: 3 minutes
No compressor consumer can avoid the terms pressure dew point, volume flow and kW power. These terms are usually used casually in exchange or during a consultation. But are the terms always so clear? In today's blog article, we pursue exactly this question and explain what the pressure dew point is and why the pressure dew point plays such a major role in the planning of your compressed air system.
The compact pressure dew point explanation
Every term needs an explanation, including the pressure dew point. The pressure dew point (DTP) indicates the temperature at which the water vapour begins to condense. In other words, the pressure dew point is used to accurately describe the water content in the compressed air. A low pressure dew point always indicates a low water content of the compressed air. This is because warm and moist air has a higher moisture content than cold air, which creates more water in the compressed air system.
You're probably wondering how exactly water and compressed air go together. Water, or technically correct condensation, is a natural by-product of compressed air generation. How much water is actually produced during compressed air generation depends on various factors: Air temperature, humidity, compressor size and the required pressure determine the water content of your compressed air. In any case, the water content of the compressed air must be kept as low as possible to avoid negative effects on your compressed air system.
Difference between atmospheric dew point and pressure dew point
The ability of the air to carry water in steam form depends on the temperature. The warmer the air, the more water it can carry. It is therefore important to know that the atmospheric dew point must not be compared with the pressure dew point.
Why does condensate form in the aftercooler of a compressor? In the compressor, the volume of the sucked-in air is reduced and in the aftercooler, the compressed air temperature is reduced. The humidity is concentrated in the smaller volume and cannot be carried at the reduced temperature. As a result, condensate fails.
What does the atmospheric dew point [°C] say? The atmospheric dew point is the temperature to which air can be cooled without condensing the moisture it contains.
What does the pressure dew point [°C] say? The pressure dew point is the temperature to which compressed air can be cooled without condensing the moisture contained in it.
Why is the dew point so much lower than the pressure dew point? Because at the pressure dew point, the moisture contained is concentrated on a smaller volume.
Why is the pressure dew point so important?
The pressure dew point is important to avoid possible damage to your compressed air system. Because too much moisture in the compressed air system can not only affect your compressed air system, but also the operating efficiency. But why is this so? Due to the high water content, pneumatic systems, pneumatic motors, valves, but also connected components can be damaged. One possible consequence of this is contamination. In colloquial language, therefore, one speaks of a contamination or contamination of the processes or even the manufactured end products.
What negative effects moisture can still have on your compressed air system, we have compiled for you here:
Corrosion of pipelines and equipment (e.B. CNC and other manufacturing machines)
Damage to pneumatic controls, which can lead to expensive shutdowns
Rust formation and increased wear of the production equipment due to washing off the lubricant
Quality problems due to the risk of discoloration, reduced quality and paint adhesion
Cold weather can cause freezing, which can cause damage to the control lines
Excessive maintenance of the air compressor and shortened service life of the systems
To keep your pressure dew point low
Basically, the lower the required pressure dew point, the higher the acquisition and operating costs of the right components. The first thought always falls back on a filter. However, a filter cannot be used to remove moisture because water vapor is present as a gas in the air and the filter can only detect solids or liquid droplets.
So in order to remove the moisture from your compressed air, the use of other processes is required. One possibility is the use of a dryer. This dries the compressed air, so that negative effects on your compressed air system and associated processes are prevented. The selection of the compressed air dryer depends on the required pressure dew point. Another possibility is that of over-compression or cooling. Our recommendation is therefore for you: Talk to your compressed air expert to find the right solution for removing the moisture in your compressed air.
The pressure dew point varies depending on the method used and is usually between -20 °C and +3 °C.
