CMS membrane technology is the effective, easy to use, and cost effective solution for removing free, emulsified, and dissolved  water from all types of lubricants used on marine vessels, including new EPA mandated environmentally acceptable lubricants (EALs).



Maintains extremely low moisture levels (dissolved, emulsified, and free) in both traditional mineral-based oils and environmentally acceptable lubricants.

Oil dehydration system works inline  — while vessels are at sea — to extend equipment and oil life and overall system reliability.

Prevents acid formation and reduces total acid number (TAN) in esters.


Removes water without removing performance additives; works effectively in dehydrating oils in the presence of both fresh and salt water.

In controlled and industrial environments, CMS’ perfluoropolymer membrane systems have been shown to remove 100% of free and emulsified water, reduce dissolved water to well below 100 ppm and, under certain conditions, remove dissolved air.

Easy to use

Simple, reliable, compact, portable, and lightweight technology with low energy usage.  Oil dehydration systems are compact enough to fit through ship hatches and down steps by one person. Once set up, the system runs with minimal oversight and management, and fewer moving parts than vacuum oil purification systems.


Low operational costs, competitive capital investment costs, and the ability to service multiple applications in rotation make this the most cost effective short and long term solution.


What is an EAL?

In the 2013 Vessel General Permit the EPA mandated that all ships 79 feet and longer use environmentally acceptable lubricants (EAL) in “all oil-to-sea” interfaces. The EPA defines an EAL as a lubricating material shown to have minimal toxicity and bioaccumulation potential, and superior biodegradability compared to traditional lubricants. In simple terms an EAL is any oil that doesn’t kill fish or humans, doesn’t build up in fish or humans, and breaks down in water in a matter of days.

If you haven’t read or are not familiar with the Vessel General Permit (VGP), here is a brief FAQ describing the important details on marine lubricants that the legislation covers.
2013 Vessel General Permit FAQ

The impact of water

Water in lubrication oil undermines the oil’s two basic functions: enabling performance and preventing damage to machinery. Even when lubricants can continue to lubricate in the presence of water, they must remain clear of water (free, emulsified and dissolved) in order prevent loss of lubricity, component damage and degradation that will shorten the service life of gears, bearings, and hydraulic systems.

Lubricant manufacturers and lubrication specialists recognize the damaging effects of water on components through acid buildup, corrosion, spalling, hydrogen embrittlement, and biomass buildup, especially with presence of salt.

The impact of water
Water is a bigger challenge for EALs (than mineral oils)

Water is a bigger challenge for EALs (than mineral oils)

Reducing dissolved water in Environmentally Acceptable Lubricants (EALs) is an important component of EAL management, and should be considered when making the switch from mineral oil based lubricants to EALs. EALs are hygroscopic, attracting a high concentration of water, even in dissolved states.  EALs are often designed to be water soluble and hold water in a dissolved state in order to meet EAL standards of biodegradability.  This water can continue to damage operational machinery, even when dissolved.

CMS technology can effectively manage free, emulsified, and dissolved water in EALs:

  • Work effectively in PAGs, esters, PAOs, as well as traditional mineral oils
  • Reduce and maintain water at ppm levels
  • When used in esters, reduces acid buildup and reverses the acidification process, in addition to removing water

Effective water management

CMS technology can remove even small quantities of water, to provide product that is 99.999+% free of water. Proven performance with esters, PAGs, PAOs and mineral oils

Effective water management
Ice Cutter

How it works

CMS membrane technology represents a step change in both the state of the art and value proposition to the customer. Working by pervaporation, an energy efficient combination of membrane permeation and evaporation, membranes separate two or more components by differing rates of diffusion through a thin polymer film with an evaporative phase change comparable to a simple flash step.

CMS membranes are most effective where water is the minor component and processed volumes are less than 5000 gallons per day. They can remove even small quantities of water, to provide product that is 99.999+% free of water and other components. CMS membrane modules can be used in harsh environments as they are chemically and thermally resistant, and work very well with viscous fluids (oils and lubricants). They also resist fouling and thus are easier to operate and maintain than alternative dewatering systems. The membrane is easy to clean because the material of construction is inert.

Please note that membranes are not 100% impermeable barriers: small quantities of the desired product will pass through the membrane. All systems are designed to capture and address these materials.

Still have questions? Check out our CMS Membrane Module FAQ.

On-board dehydration success stories

Many vessels have used CMS’s membrane-based dehydration solution to solve their issues with water contaminating crucial lubrication systems. Check out some summaries of our past successes:

Ice Cutter Case Study

Tugboat Z-drive Case Study

Still not sure about how a CMS membrane solution would look onboard your vessel? Here are the most common questions we field from ship owners and engineers.

Oil Dehydration FAQ

2013 Vessel General Permit FAQ

Have an EAL that needs dehydration?

Contact us about ordering a system, testing your EAL, or developing a custom solution.