Portable Moisture Measurement for Compressed and Specialized Gases

Automatic wastegate with oxygen cylinders

How to ensure quality, safety and compliance for nitrogen, hydrogen and oxygen

The use of on-site gas generation systems has increased dramatically in recent years.  In particular, the advent of high-efficiency pressure swing adsorption (PSA) and hollow fiber and ion exchange membrane technologies has enabled end users to generate specialized gases – typically nitrogen, hydrogen and oxygen – on demand and at competitive costs.  Perhaps as importantly, the use of on-site gas generation systems frees end users from the constraints and environmental concerns associated with traditional bulk deliveries and storage, and the health and safety issues of handling gas cylinders. 

Although there are clear benefits to on-site gas generation, the growing use of these systems has revealed a number of potential issues; in particular, the need to be able to prove consistent gas quality. 

Unlike bulk or bottled gas systems, which are produced and supplied under strictly controlled conditions and carry a guarantee of quality, the output from on-site gas generators is determined by the conditions under which they are operated and monitored.  Gas quality, defined by the level of hydrocarbon, particulate or moisture contamination, can therefore be variable. 

This may not be a significant issue in some industrial applications, but, in healthcare or advanced manufacturing, any form of contamination will have severe consequences. 

Measuring trace moisture in specialized gases 

The latest gas-generation systems incorporate filters to remove oil and particulates from the compressed air feed.  However, not all use moisture sensors to detect contamination in the output gas flow from drying units.  Consequently, it is possible for moisture to travel downstream to the point of use.  In industrial applications, this can affect production quality, while in healthcare it can increase the potential for microbial growth and thus the risk to patients and sophisticated machines. 

Help is at hand! 

In our 50th year of developing and manufacturing advanced moisture and hydrocarbon dew-point measurement sensors and analyzers, we’ve launched an innovative new portable pressure dew-point hygrometer. 

The new Easidew PDP Dryer Portable 

The Easidew PDP Dryer Portable is designed for use with compressed air and specialized gas systems.  It will help service, maintenance and production engineers ensure that the quality of gas from dryer outputs complies exactly with the criteria required for each application. 

Automatic wastegate with oxygen cylinders

The new unit has the following features:

  • Lightweight, compact and rugged 
  • Easy to use
  • Large color LCD display
  • Simple navigation options
  • Quick-release gas input and output connections
  • Automatically measures dew point, pressure and temperature in real time
  • Logs data to an internal memory from where it can subsequently be downloaded via a standard USB-C port. 

  • The technical specifications include a dew-point measuring range from -100 to +60 oCdp, at line pressures up to 20 barg and operating temperatures from -20 to +50 oC.  Accuracy is ±2 oCdp, with a fast response to fluctuations in moisture levels.  The Easidew PDP Dryer Portable is certified to ISO 8573-1 and is available with a choice of integrated ceramic metal-oxide or thick-film moisture sensors, providing compliance to Class 1-4 or 2-4 respectively. 

    In common with all our sensors and analyzers, the new portable is backed by a full range of customer support services, including our sensor calibration and exchange program.  

    Making quality and compliance quick and secure

    The new Easidew PDP Dryer Portable is an ideal instrument for all engineers working in critical applications, where it is essential that gas quality and compliance meet the highest safety standards.  Regular use as part of comprehensive monitoring and control procedures will provide quick and accurate detection of changes in trace moisture levels, allowing immediate adjustments to be made to dryer operation. 

    Not only will the new portable save time and improve dryer efficiency, it will also provide a detailed audit trail, for full traceability and peace of mind. 

    If you would like to discuss your requirements, please contact our team today.  

    ISO 8573-1 is the standard that governs the quality – or contamination levels – of compressed air.  Increasingly, as compressed air and specialized gas generators share similarities when it comes to gas drying, the standard is being used to measure dryer output as a means of controlling the quality of gases such as nitrogen, oxygen and hydrogen. 

    ISO 8573-1 specifies ten Classes of purity, based on the levels of oil, particulates and moisture.  Of these, the first six relate to trace moisture contamination, with one to four being most commonly used for gas drying systems. 

    The pressure dew point for each is specified as: 

  • Class 1 = -70 oCdp 
  • Class 2 = -40 oCdp 
  • Class 3 = -20 oCdp 
  • Class 4 = +3 oCdp 

  • The term ‘pressure dew point’ simply refers to the humidity of a gas under a pressure greater than atmospheric pressure.  To learn how to calculate pressure dew point click here.  

    Related Category

    Portable Hygrometers and Dew Point Meters

    Related Information

    Compressed Gas Generation and Treatment

    Compressed Air

    Related Blogs

    How to Address the Skills Shortage in the Moisture Measurement Industry

    The Challenges of Industrial Moisture Measurement

    Compressed Air Efficiency




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    Related Products

    Compressed Gas Dew Point Meter - Easidew PDP
    Dryer Portable
    Portable Dew-Point Hygrometer - Michell MDM300 Series
    Diagnostic Communication Tool for Michell Easidew and Pura


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