Dew Point and Dew Point Temperature of Compressed Air

Water vapor is one of the main byproducts of using a compressed air system. While this is a natural part of the process, having some way to dispose of or remove the water vapor from the operating area is essential. It may not look it, but compressor systems are sensitive machines that need optimal air temperature and vapor levels to function at their best.

Most industries manage this dilemma by meticulously checking the air compressor’s dew point or teaching personnel preventive maintenance techniques to maintain ambient temperature. However you manage it, it’s crucial that you continuously monitor the dew point temperature in your compressed air room. It will keep your expensive equipment in working order for much longer and prevent you from shelling out money for costly repairs or, in extreme cases, replacement.

In This Article

What Is the Dew Point of Compressed Air?

When the air can hold no additional water vapor, the vapor condenses into a liquid form, lining your machine and the room around it with moisture. This point of compressed air temperature saturation — the dew point — occurs when the air reaches a certain temperature. The temperature at which this occurs varies between air compression systems, but it generally falls between 50 and 94 F or 10 to 35 C.

Atmospheric Dew Point vs. Pressure Dew Point

Atmospheric dew point occurs naturally, while your compressor system induces the pressure dew point. While it may seem confusing to have two different dew points, both pressure and atmospheric dew point can have a significant impact on your equipment and operations.

atmospheric dew point vs pressure dew point

Atmospheric Dew Point

The atmospheric dew point is the temperature at which air becomes saturated without pressure influence from an external source like an air compressor. It applies to fully de-pressurized atmospheric conditions. Meteorologists and pilots will use the atmospheric dew point to help predict weather patterns.

Pressure Dew Point

Pressure from a compression system will change a gas’s dew point temperature — you must account for this pressure if you’re taking measurements. Since the pressure dew point relates to air or gas saturation levels due to external pressure, it’s almost always higher than the atmospheric dew point.

Why Is Dew Point Important for Air Compression?

Depending on your particular industry, you might need to account for pressure dew point. Monitoring the dew point or controlling it with compressed air dryers can be extremely important. So, why is dew point important for air compression?

In some areas, such as applications in the pharmaceutical industry, it is vital that your method of moving product stays uncontaminated by moisture. In other areas, you may be working with very low temperatures where air could conceivably freeze in pipes, causing a shutdown. In many cases, extra moisture can lead to corrosion and rust, as the water can remove any lubricants and oils present that prevent material breakdown from happening. This then causes inaccurate machine readings and, in extreme cases, control failure.

Without dew point monitoring, sensitive equipment could be exposed to severe damage, interfering with the quality of the end products. You can encounter several issues due to moisture damage, including:

  • Reduced machine functionality as condensed water freezes in flow lines.
  • Equipment failure and incorrect readings due to rust accumulation.
  • Loss of lubricants, leading to extensive corrosion that breaks down moving parts.

Monitoring and maintaining an ideal dew point is vital to ensuring your industrial facility’s longevity and efficiency, making it a critical part of your operation. You must constantly and accurately monitor dew points through a sensor to prevent equipment failure, unwanted condensation on product or process lines or bacterial formation.

How to Measure Dew Point in Compressed Air

You’ll need a dew point sensor to perform accurate dew point measurements. Your air dryer may have this specialized sensor built-in — if not, you will need to incorporate it into your air compressions system.

If your air dryer includes a dew point sensor, the sensors will continuously provide accurate data as compressed air flows through the dryer. These built-in sensors require very little adjustment or calibration throughout the year, allowing your operations to run more smoothly and efficiently.

Ensure these sensors are isolated from the compressed air line to provide you with more accurate readings. Additionally, dew point sensors need flow-regulating devices installed along with the sensor to control air flowing past the sensor. When the regulating device is upstream of your dew point sensor, it can control the airflow to let the sensor get a precise dew point reading.

How Do Air Dryers Reduce Dew Point?

How Do Air Dryers Reduce Dew Point?

Air compression systems with dryers are an ideal solution to the problem of compressed air applications that are sensitive to dew point. This dryer and air compression system combination can process gas and remove moisture from your compressed air. An air dryer also keeps you from having to perform more time- and labor-intensive maintenance, like vacuum pumps. A typical air compressor will produce air with a dew point as high as the compressor room’s air temperature.

There are two kinds of dryers you could use to reduce your dew point efficiently. Both systems dry the air and monitor the dew point. Additionally, they both include built-in transmitters that verify your equipment is maintaining the air at the required level. The right dryer for you depends on your operation’s budget and needs:

  • Refrigerated dryer: A refrigerated dryer is less expensive than a desiccant system. You can have dew points as low as 39 F or 4 C. These dryers are popular because they are relatively inexpensive and easy to maintain and operate. The dryer cools the air, turning it into water. The water then flows into a water trap away from the dryer, where it is reheated to room temperature.
  • Desiccant dryer: Desiccant drying systems have two towers filled with highly absorbent materials. While one tower takes in water, the other undergoes a reverse process to remove moisture from its hygroscopic material. They take turns absorbing and removing moisture. While this industrial system is more expensive than a refrigerated dryer, it can achieve dew points as low as -40 F or -40 C.

Using an air dryer can significantly improve the quality of your compressed air over time. With less moisture in the air, measuring the temperature of your compressed air should take less time and keep your pressure dew point below levels at which excessive vapor is released into the air. Once you get used to the system, you should be reading temperatures within the typical range consistently.

Calibrating Air Dryer Systems

While your air dryer should generally do a good job of monitoring your air dew point, it is important to occasionally check and calibrate your compressed air dryer’s dew point measuring system. You can easily measure pressure dew point with the right portable instrument and compare your finding to the reading on the air dryer to ensure accuracy. Calibrate your system at least once a year or anytime you are suspicious about the readings you are getting for your compressed air.

Choose Fluid Aire Dynamics for Compressed Air and Air Dryer Systems

Choose Fluid Aire Dynamics for Compressed Air and Air Dryer Systems

If you have a company that requires dry, compressed air in Pennsylvania, Maryland, New York, New Jersey, Delaware, Northern Virginia or D.C., the compressed air system provider to call is Fluid Aire Dynamics.

We have a wide range of compressed air and gas systems for companies across a variety of industries that offer superior capabilities and performance. Both lubricated and oil-free air compressors are available, as well as air and gas dryers and dehydration systems, including refrigerated dryers, desiccant dryers and more.

To learn more about our equipment offerings and find out the best compressed air system for your particular business, please contact us today.