Why Measure Dew Point?
Measuring dew point and ambient temperature is the simplest way to monitor dryer performance and detect moisture issues before they can cause a problem. Moisture in compressed air can cause corrosion and component failure, contaminate products, and affect production performance.
What should you look for on a Dew Point Graph
The ideal pressure dew point (PDP) graph shows a stable pressure dew point which doesn’t fluctuate with ambient temperature or flow changes. This indicates that the dryer is sized correctly and is working well. If the pressure dew point fluctuates with ambient temperature, has large spikes or the pressure dew point is too low or too high, there may be a problem with the dryer or your condensate drains.
The graphs below show common pressure dew point and dryer issues:
- Stable Dew Point
- Unstable Dew Point
- Dew Point too High
- Dew Point too Low
- Dew Point Spikes
If you need help measuring the pressure dew point of your compressed air or gas system, or if you need a dew point sensor and data acquisition system, contact us.
Stable Dew Point Graph
In the graph below, dew point (black line) is relatively stable and doesn’t fluctuate as the ambient temperature changes (green line). This indicates that the dryer is sized correctly, is working well and is well maintained.
Unstable Dew Point Graph
In the graph below, the dew point of a compressed air system (black line) rises and falls with the ambient temperature (green line). This indicates that the dryer is not working properly. If the unstable dew point isn’t corrected, the dryer may be overwhelmed in summer or humid weather resulting in liquid condensate appearing throughout the factory.
Suggested actions to fix unstable dew point:
- Check dryer is functionally correctly
- Check dryer is sized correctly.
- Service dryer
- Check condensate drains on the dryer, filters and wet receiver are working correctly
- Consider installing a zero-loss electronic condensate drain
- Consider replacing old, faulty dryers with correctly sized dryers
Dew Point Too High
In the graph below, the dew point (black line) is stable which indicates that the dryer is well sized and installed correctly. However the dew point is too high for the type of dryer installed (average dew point of 4°C).
The compressed air system in the graph below uses a refrigerant dryer. Refrigerant dryers should provide a stable dew point of between +1°C to +3°C.
Suggested actions to fix high dew points:
- Request the Dryer Technician service the dryer and check the dryer’s settings
- Check condensate drains on the dryer, filters and wet receiver are working correctly
Dew Point Too Low
In the graph below, the dew point is stable which indicates that the dryer is well sized and installed correctly. However the dew point is too low for the type of dryer installed (average dew point of -1°C).
The compressed air system in the graph below uses a refrigerant dryer. Refrigerant dryers should provide a stable dew point of between +1°C to +3°C and should not drop below 0°C at any time. At or below 0°C there is significant risk of the condensate freezing inside the dryer which could lead to permanent, irreparable damage to the dryer.
Suggested actions to fix low dew points:
- Request the Dryer Technician service the dryer and investigate if the hot gas bypass valve is set correctly.
Dew Point Spikes
In the graph below, the compressed air system is shut off at night. In the morning, when the system is turned on, the dew point (black line) spikes. This suggests that the compressors and dryer are all switched on at the same time. As refrigerant dryers take time to reach their operating temperature, starting the equipment simultaneously leads to moisture ingress into the main system.
Suggested actions to fix dew point spikes:
- Turn on the refrigerant dryer 15 – 30 minutes prior to starting the compressors to prevent initial moisture ingress into the compressed air system.
Need Help with Dew Point?
Purchase Dew Point Sensors
Buy a dew point sensor from Compressed Air Alliance. We offer a range of sensors to suit different dew points and different applications. Our sensors are suitable for compressed air and inert gases.
View and Analyse Dew Point Data
All our dew point sensors are compatible with our Data Acquisition System. The Data Acquisition System allows you to view and analyse data in real time from any device with an internet connection.
Measure your Compressed Air System
Compressed Air Alliance offers temporary and permanent monitoring and measurement of your compressed air and gas system. We can measure flow, pressure, power, temperature, consumption, dew point and system efficiency.
Advice and System Upgrades
Need help identifying issues, selecting the best options or understanding your dryer or compressed air system? Compressed Air Alliance can take the pain out of selecting new equipment and help you avoid the pitfalls.
Contact Us
If you need help measuring the dew point of your compressed air system, contact us.
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