Membrane Dryers
By Mark Haynie and Joshua Belisle · Edited by Dana Gardner
Published August 9, 2024 · Reviewed by Mark Haynie · July 27, 2026
Summary
What is a membrane resin dryer?
A membrane dryer is a compressed air dryer that uses a polymer membrane to separate water vapor from the compressed air and vent it out of the system. A plain compressed air dryer produces process air at roughly 0 to 20°F dew point, which can vary week to week and season to season. Adding the membrane brings the process air to -40°F dew point.
A membrane dryer is a type of compressed air dryer that uses a membrane to remove moisture and other contaminants from the air. The membrane is typically made of a polymer material, such as polyamide or polyurethane, and works by separating the water vapor and other contaminants from the compressed air.
The operation of a membrane dryer involves passing the compressed air through the membrane, which has a series of tiny pores. The pores allow the air to pass through while trapping the water vapor and other contaminants, which are then vented out of the system.
These dryers are commonly referred to as compressed air/membrane or membrane/compressed air dryers but the keyword is membrane. There is a big difference between a “compressed air dryer” and a compressed air dryer with a membrane. A compressed air dryer does not produce -40 dew point process air (it’s more like 0-20 dew point) and can vary week-to-week and season to season.
A membrane improves the compressed air dryer by ensuring -40 dew point process air so the drying capability of a membrane dryer is much better than a conventional compressed air dryer.
There is also a big difference between a membrane dryer with a built-in membrane as compared to one with an add-on membrane. Those with add-on membranes – use up to three times as much energy as as those with built-in membranes.
Types of Resin Drying Systems
Silo Dehumidification/ Hot Air Dryers
What is a silo dehumidifier and how does it work and compare with other resin drying systems?
The principle of compressing air in factories for power tools and other high-pressure uses has a side benefit for the world of resin drying.
What is a membrane resin dryer and how does it compare to a compressed air dryer without a membrane?
What is a vacuum resin dryer and how does it draw moisture away from plastic pellets in vacuum processing?
Dual Bed (also called Twin Tower) dryers used to be the most commonly purchased type of resin dryer. A look at why, and where the technology has progressed.
The advantages of desiccant wheel dryers include operating at a low temperature, which is important for preventing thermal degradation of the resin.
Technically, crystallizers are not dryers. They are used to convert PET from an amorphous, back to a crystalline state for re-processing.
Drying Hoppers for Plastic Resins
Drying hoppers are part of most drying systems. At a glance, they look much the same, but there are certain features you should look for.
What are the benefits of gas-fired process heaters for drying plastic resins?
Resin drying machines that can be moved from machine to machine within a plastics processing plant have advantages and disadvantages over a central drying system.
Properly designed Central Drying Assemblies are easily connected together to save installation costs.
PET Energy-Saving Drying Systems
Learn about the keys to drying PET efficiently while saving space and energy.
Frequently Asked Questions
What is the difference between a compressed air dryer and a membrane dryer?
A compressed air dryer without a membrane does not produce -40°F dew point process air; it runs closer to 0 to 20°F and can vary week to week and season to season. A membrane dryer adds a membrane that removes water vapor from the compressed air, bringing the process air to -40°F dew point, so its drying capability is much better.
Is a built-in membrane better than an add-on membrane?
There is a big difference between the two. Membrane dryers with add-on membranes use up to three times as much energy as those with membranes built in. When comparing membrane dryers, check whether the membrane is part of the dryer's design or has been added to a conventional compressed air dryer.
What is the membrane in a membrane dryer made of?
The membrane is typically made of a polymer such as polyamide or polyurethane. Compressed air passes through the membrane, which has a series of tiny pores. Water vapor and other contaminants are separated from the air stream and vented out of the system, leaving drier process air for the resin.
About the Authors
Vice President of Moisture & Drying Technologies, Novatec
Mark Haynie has designed and installed resin drying systems for more than 40 years, working in thousands of plastics plants across the industry. As Novatec’s Vice President of Moisture & Drying Technologies, he leads the company’s drying technology group, including its work on moisture measurement and predictive drying. He also serves as a technical reviewer for Novatec’s Drying Knowledge Center and has authored numerous technical articles and whitepapers on resin drying and moisture.
Mark earned a Bachelor of Science in Chemical Engineering from Virginia Tech.
Through Novatec’s Ask the Expert program, Mark regularly helps processors troubleshoot drying performance and resin-moisture challenges.
Technology Manager, Novatec
Joshua Belisle is Technology Manager at Novatec, where his work focuses on simulation and technology development for resin drying. He earned a B.S. in Mechanical Engineering with a minor in Engineering Business from the University of Virginia in 2023 and joined Novatec that same year. Joshua uses simulation tools to investigate previously difficult-to-measure aspects of the drying process, helping Novatec better understand airflow, heat transfer and other variables that influence resin-drying performance.
Related Articles
Understand internal and surface moisture and why starting moisture affects resin drying.
Explore compressed air, membrane, and dual drying zone designs.
See how one dry-air source serves multiple hoppers with independent temperatures and controls.
Ask the Plastic Drying Expert
Author Profile:
Mark Haynie has designed and installed resin drying systems for more than 40 years, working in thousands of plastics plants across the industry. As Novatec’s Vice President of Moisture & Drying Technologies, he leads the company’s drying technology group, including its work on moisture measurement and predictive drying. He also serves as a technical reviewer for Novatec’s Drying Knowledge Center and has authored numerous technical articles and whitepapers on resin drying and moisture.
Mark earned a Bachelor of Science in Chemical Engineering from Virginia Tech.
Through Novatec’s Ask the Expert program, Mark regularly helps processors troubleshoot drying performance and resin-moisture challenges.