Dew Point Measurement in Compressed Air Industrial Applications
Application Note

Dew Point Measurement in Compressed Air Industrial Applications

By 10/12/2021December 8th, 2022No Comments

Optimize Compressed Air Quality With The Right Dew Point Instrument

Dpstar provide a wide range of dew point instruments for trace moisture measurement in gas and compressed air. The range includes dew point sensors, meters, transmitters, probes and dew point instrument accessories. Dpstar extensive range of user-friendly dew point measurement instruments have been designed to meet the most demanding requirements and needs expressed by the industry. Our dew point measurement instruments are built using quality components, to the highest standards and specifications, compliant with our quality system which is certified to ISO 9001 and accredited ISO 17025 calibrations. We can therefore offer all our products with a generous warranty, guaranteeing reliability and performance. Additionally, we employ experienced sales and technical engineering staff to ensure that customers’ dew point applications are fully understood, so that we can provide solutions that are not only cost effective and on time, but also satisfy the most rigorous and demanding specifications.

Dew point is not only a process variable to be measured in industrial applications, but also a common contaminant which must be controlled. Whether in gas or in liquid form, dew point has the power to dramatically reduce product quality, damage industrial equipment, and significantly increase operating costs. The most accurate method of measuring the dew point of compressed is by using a dew point sensor. This device is custom-built and incorporated into an air compressor unit to provide real-time information on the water vapor content of the air flowing through it. These sensors require minimal calibration and can function effectively for extended periods on a single calibration check.

A number of problems are caused by excessive moisture in a compressed air system

When warm compressed air leaves the compressor, it contains a high level of water vapour. As the air travels through the compressed air distribution network it cools, and the water vapour will condense on any cold surfaces it comes into contact with. The condensation can form in fittings and fixtures along the distribution pathway, or inside tools, equipment and machinery once the compressed air reaches its destination.

Penetrate virtually any surface

Render test results useless

Result in poor product quality

Cause corrosion in tubing

Lead to ice formation at low temperature

Cause premature wear & equipment failure

Dew Point Applications

Pharmaceutical

Continuous monitoring and control of dewpoint is often a requirement for instrument air, drying processes, packaging, and actuating process control valves. The risks associated with letting dewpoint levels go unchecked can include equipment failure, condensation in process lines and on finished product, and the potential for bacterial formation. Compressed air may be used for a number of applications in the pharmaceutical industry, such as raw material transport, processing equipment, pneumatic power sources, and cleaning. The importance of knowing the dewpoint in a compressed air line may be critical for some applications but less relevant for others. For example, bulk solid and powder conveyers used for moving product rely on sufficiently dried and filtered air in order to perform their function properly and prevent product contamination.

Refrigerated Air Dryers

Refrigerated dryers operate by using a refrigerant to cool the supply air with heat exchangers (usually to between 35ºF to 40ºF) and condense out water vapor for removal by a moisture separator and drain. Due to their relatively low initial cost, long term reliability and minimal maintenance requirements, refrigerated dryers often do not integrate a dewpoint transmitter into their design for monitoring or control purposes.

Laboratory Environments

Laboratory environments are often designed to maintain a controlled atmosphere in order to eliminate airborne contaminants and any sources of error that may interfere with testing. Dewpoint can be an important parameter to control. This is usually accomplished through the environmental control system and has little to do with compressed air. Some lab equipment, such as glove boxes, may require their feed gas to meet an established dewpoint level in order to maintain the inert atmosphere of the chamber.

Desiccant Air Dryers

Desiccant air dryers can benefit from a dewpoint sensor for monitoring dryer performance, controlling desiccant tower regeneration, or both. Most regenerative desiccant type dryers (heated or heatless) produce a dewpoint of around -40ºC/ºF. Installing a dewpoint instrument with a display or with built in alarm relays to measure the exit air from the dryer is a smart way to ensure good dryer performance. However dryer efficiency can be significantly improved by using a dewpoint device to control the regeneration cycle – known as Dewpoint Demand Switching (DDS). Desiccant dryers operate using two separate towers containing desiccant – one tower is always in operation while the other tower is being regenerated or purged using a portion of the dried exiting air. Some towers switch based on a timer, regardless of whether the desiccant has been fully saturated. By integrating a dewpoint sensor with the dryer control system, the towers will not switch until the dewpoint transmitter senses a degrading dewpoint temperature, thus ensuring full utilization of each desiccant tower and minimizing wasted purge air.

Food & Beverage

Compressed air is a very important tool for food processing and packaging. Food production includes processes like canning, freezing, and dehydration. In this industry – compressed air is used for blow-off applications, cleaning, sorting, cutting, shaping, and conveying food products. While a little moisture within a compressed air system is to be expected, the accumulation of significant condensation can damage sensitive equipment and deteriorate the quality of finished products. In this regard, monitoring the compressed air dew point is vital to ensuring the working life of your machinery is preserved and your product quality is standardized.

Metal Manufacturing

At metal manufacturing facilities, air compressors are used at the finishing end for a variety of processes. As newly formed metals take shape, pressurized air is used to power the pneumatic tools that cut raw metal supplies into measured lengths and defined shapes. Air compressors are also used to power the refining tools that smooth out and clean the surfaces of metal products. Compressed air systems are used for cooling, heat generation, equipment maintenance, and power tool operation. During the production of compressed air, an unavoidable by-product is water vapor which condenses onto the air compressor system or attached process components. To avoid condensation, the compressed air must be dried to a point where its dew point is lower than the temperature of the coldest surface that the compressed air could come into contact with at any point during the production process.

Benefit From Industry-Leading Reliability & Accuracy With Vaisala Drycap Technology

Vaisala DRYCAP was the world’s first polymer sensor for measuring dew point. The DRYCAP sensor is particularly renowned for its reliable performance in hot and very dry environments. The technology offers long-term accuracy and industry-leading reliability, ensuring dew point measurement you can trust. Dpstar can help you choose the correct dewpoint measurement instruments for your applications.

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Off Jalan Puchong, 47160 Puchong,
Selangor Darul Ehsan, Malaysia.
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