Peter Dufresne Jr.

Executive Vice President, EPT

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We are pleased to share with you our third newsletter that offers a fresh perspective on technical issues facing the industry.

In this issue we provide a user’s perspective into lubricant varnish. We have seen the struggle customers are facing first hand, even after purchasing various varnish removal systems. Customers buy systems, but often they don’t fully address the issue. We hope that the following articles will assist users in gaining the upper hand and move the lubricant varnish issue to the RESOLVED folder, once and for all.

Thank you for your interest.


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Current Newsletter Topics:

  1. Straight Talk on Varnish
  2. What to Consider When Purchasing Varnish Removal Systems
  3. Training Courses


Register now to read our Varnish White Paper


Part 1: Bad oil or bad maintenance?

Users often complain that their lubricant is not performing well because the varnish potential (MPC) number is elevated, or their oil is oxidizing when additives are still present. This drives users to search for a different lubricant or after-market additives when the problem lies with the expectation being placed on the oil, namely that little to no maintenance should be required.

The misconception is that only poor quality lubricants oxidize, and that varnish is a result of improperly formulated oils. While lubricant quality is a key criteria, in reality all lubricants break down due to oxidation – even with additives – and that increasing varnish potential over time is normal when dissolved oxidation products are allowed to accumulate.

Rather than discussing more effective varnish removal systems, vendors are now moving the discussion toward synthetic oils and after-market additives to extend the operating range of lubricants with high MPC values. While there is a place for advanced lubricant technologies, simple and more cost effective solutions are available using conventional lubricants to permanently remove dissolved oxidation products and maintain ultra-low MPC values.

EPT has recently published a white paper that discusses varnish formation in depth. Oxidation starts on the very first day a lubricant is put into service. The oxidation process creates a dissolved breakdown product, or varnish precursor, that will accumulate in the oil over time until it becomes saturated. Once a saturation point is achieved, these varnish precursors physically convert from the dissolved form into solid deposits.

The saturation point varies throughout the mechanical system due to differences in temperature and pressure, which dictates where varnish deposits will form first. For this reason, it is important to keep the lubricant in an unsaturated state by removing the varnish precursors. By doing so, you can prevent the lubricant from becoming saturated at any temperature or pressure present in the mechanical system and prevent varnish formation.

Register now to read our Varnish White Paper.


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Learn more on our website: Turbine Lubricant Varnish


Varnish removal technologies can be classified into two main categories: 1) Particulate removal including electrostatics, balanced charge agglomeration and depth media filters, and 2) Dissolved breakdown product removal including ion exchange and ion charge bonding technologies.

As discussed above, varnish is the consequence of dissolved breakdown products accumulating past the point of saturation. Since the key to prevent varnish is to prevent saturation, only varnish removal technologies that remove the dissolved oxidation products and return the oil to an unsaturated state can prevent varnish.

While particulate removal technologies are excellent tools, and are capable of removing insoluble contaminants once saturation is achieved, they are not able to prevent saturation and therefore not able to truly solve the varnish issue. For this reason ion exchange and ion charge bonding technologies are preferred.

    Important considerations when selecting a varnish removal system

    1. Does the system work during normal turbine operation when the varnish is dissolved in the oil?

      While particulate removal technologies offer very important benefits, such as reducing wear, they are ill equipped to remove varnish because it can take up to 72 hours to form after oil is cooled to ambient temperature. This is why the ASTM D7843 varnish removal test requires a 68-72 hour sample “aging” period. In an effort to accelerate this transition, some particulate removal systems use a cooler on the inlet to try and force dissolved varnish precursors out of solution before they go through the filter. Using an ion exchange or ion charge bonding system that can remove varnish precursors when they are dissolved is much more effective and will offer 24/7 protection regardless of turbine operating condition.
    2. What is the flow rate of the system?

      Optimal lubricant varnish prevention using ion exchange requires a system that cycles the entire reservoir volume >1x/day through the filtration system. Because the flow rate is constrained based on the volume of ion exchange resin used, attention needs to be paid to the filter size. For lubricants with high varnish levels requiring restoration, higher reservoir exchange rates may be in order.
    3. What is the cost of ownership over the lifespan of the system?

      The cost of ownership of a varnish removal system includes the initial cost of the system, maintenance and consumables over its lifetime. The latter can be calculated by the resin bed volume of the filter (e.g. per in3 or cm3). Special care is required when evaluating this key point. As stated in #2, the volume of resin used also determines the flow rate of the system, so attention must be paid to the filter size.
    4. What is the support for the system?

      Quality vendors should be available for on-site start up and training as well as ongoing monitoring to document the success of the system. In addition, users need to evaluate the oil analysis used to determine initial oil condition and show success as standard testing often misses key indicators.


    Next Course Date:
    June 22, 2016

    For more information please view our training brochure.

    To register please contact Barbara Creighton at
    or email.


    Looking to understand best practices in lubricant management in a vendor-neutral environment? Join us for the first in a 3-course series dedicated to providing you with the practical knowledge you need to optimize your lubrication management.

    The Basics of Machinery Lubrication and Sampling for Oil Analysis – An Introduction.

    Modern production equipment requires sophisticated lubrication management to ensure reliable, safe, and efficient operation. This series of three, one-day, vendor-neutral training classes offered by LubeWorks and EPT will provide expert training on current best practices in lubricant management applicable to a wide range of industrial lubricant applications.

    These courses are targeted for Reliability Engineers, Maintenance Personnel, Operators and Technicians that work with lubricating oils on a regular basis. Knowing how to implement or improve a lubricant management program is critical to the success of your operation. This specialized training offers an ideal opportunity for lubricant users to increase their knowledge and skills so they can perform their responsibilities with a higher level of understanding and expertise.

    Please view our training brochure for details on what you will learn in this installment of the series.