Understanding and Evaluating Lube and Hydraulic Oil Purification Systems

Lubrication and hydraulic fluids for industrial machinery will most often suffer from water contamination.  AMPTIAC Quarterly reports that 75% of hydraulic system failures result from fluid contamination.  Water is second only to particulate as a source of significant contamination of machine oils.  Rotating equipment is especially vulnerable.  For example, as the water content in turbine lube oil gradually increases, the machine develops multiple failure points.  These include bearings, bushings, seals, shafts and more.

While other forms of contamination must be mitigated, water contamination presents unique challenges.  Free and emulsified water are easily identifiable.  Free water accumulates and stratifies, while emulsions typically appear as cloudiness or rag layers.  Dissolved water is invisible but just as toxic as the other forms.  According to NORIA, “Depending on the oil type and temperature, a bearing can lose 75% of its life due to water contamination before the oil becomes cloudy.” Reducing water content well below the saturation level is desirable.  This prevents the liberation of free water in oil coolers while curtailing additive depletion and degradation of critical oil properties such as viscosity, lubricity, and film strength. “Oil Purification Systems,” aka “Oil Purifiers,” utilizing vacuum dehydration, were designed for these challenges.


PowerFlow XLP5 Oil Purifier

Figure 1 – XLP Series Oil Purifier  (Visit our XLP Series product page and request a quote.  https://www.pwrfs.com/product/lube-hydraulic-oil-purifiers/ )

As discussed here, their primary function is removing ALL forms of water from the oil.  Most also remove free and dissolved gases, as well as particulate contamination.  Therefore, we define an “Oil Purifier” or “Oil Purification System” as an integrated process that removes free and dissolved water and gases, oil/water emulsions, and particulate.  Though often advertised to the contrary, most oil/water separation technologies do not intendedly remove dissolved water or any gases.  This is where systems that utilize vacuum dehydration are distinguished from those employing coalescing filters, water absorption media, corrugated plates and centrifuges.  An Oil Purification System with vacuum dehydration is recommended when the total water content increases in lube or hydraulic fluid systems.


Sources Of Water Contamination

There are several ways water enters lube and hydraulic fluid systems.  These include:

  • Direct absorption from humid air in the headspace of the oil reservoir
  • Rapid condensation in the headspace of the oil reservoir
  • Rain and washdown water ingression through leaky hatches and seals
  • Leakage from steam seals
  • Leakage from oil coolers and heat exchangers

Preventative measures for mitigating these ingression mechanisms should be in place.  However, water will likely find its way into these systems.  This is when an Oil Purifier is convenient and often the most reasonable solution.


Process Technology Applied in Oil Purifiers

Before exploring the benefits of using Oil Purifiers, it is essential to understand how they work.  Commonly, Oil Purifiers utilize vacuum dehydration technology for enhanced water removal performance.  In some systems, the oil may also be heated to optimize dehydration.  Under vacuum, the required thermal input is reduced.  Less heat prevents thermal oxidative stress of the oil.  Vacuum dehydration is the most efficient way to lower water concentration below the threshold needed to protect vital machine components adequately.

Two commonly used vacuum dehydration processes are “vacuum mass transfer” and “flash distillation.” Vacuum mass transfer uses moderate vacuum levels (ࣘ≤22inHg) and heat (≤120 deg. F) in a process that accelerates moisture evaporation with minimal risks of oil degradation. Flash distillation uses deep vacuum (25-28 inHg) and high heat (150+ deg. F) to boil or flash water from the oil in a process carrying a higher risk of oil degradation.  We only discuss vacuum mass transfer here.

Inside these dehydrators, preheated oil is distributed in a thin film over some form of media, such as packing rings.  The increased surface area significantly improves the efficiency of the process.  As seen in Figure 2, there are three critical features needed to achieve this:

  1. A vacuum chamber/tower where oil flows from top to bottom while dry air flows from bottom to top
  2. A means of distributing the oil evenly over the inside cross-section of the chamber/tower by creating an oil spray in the form of an umbrella
  3. A flow configuration where the oil passes from top to bottom through/over a media, such as packing rings, that expands the surface area and creates a thin, cascading film

Dry air is continuously drawn upward through the packing over the thin film of oil.  Water and air/gas molecules transfer from the oil to the upward-moving air.  The air/water vapor exits the chamber’s top and may be routed to a condenser to manage water collection.  Finally, it is expelled through the vacuum pump.  Dehydrated/de-aerated oil exits the bottom of the chamber and is typically routed through a particulate filter to achieve the desired cleanliness level.  This system could run as a batch or continuous process, but the latter is more efficient.

Vacuum Dehydration Process for Oil Purifier

Figure 2 – Diagram depicting a simplified view of oil dehydration in a vacuum chamber


Why Use Oil Purifiers

Before investing in an Oil Purification System, it is essential to consider the long-term benefits.


Benefit #1: Improved safety

Safety is always number one.  Especially with rotating equipment, mechanical failure and control issues can result in serious accidents.  The average cost of a recordable injury is tens of thousands of dollars.  A lost-time injury costs even more.  Dangerous equipment failures such as broken shafts and hydraulic overspeed can be avoided by maintaining the purity of lube and hydraulic fluids.  Prevention of a single injury will always justify the cost of an Oil Purifier.


Benefit #2: Less frequent oil changes

It is easy to see how stretching the useful life of lube and hydraulic fluids is economically beneficial.  Factors that have a significant impact on the return on this investment are:

  • Reducing the money spent on replacement fluid
  • Lowering labor costs and freeing up time for other maintenance and repair projects
  • Shrinking disposal fees

Accordingly, extending the lifespan of the oil by several thousand hours makes a good case for investing in an Oil Purification System.  Our infographic examines the relationship between oil health diagnostics, various contaminants and oil purifiers.


Benefit #3: Less unscheduled machine downtime

Often, machinery endures significant wear and tear or massive and sudden breakdowns that can cause immense losses to a business.  According to Forbes magazine, “next to a safety or environmental mishap, unplanned/unscheduled downtime represents one of the costliest events at any industrial or manufacturing plant.” Every event is different, but costs can run into millions of dollars.  When the downtime results from contaminated lube or hydraulic fluid, it is almost inevitable that the costs will dwarf investing in an Oil Purifier.  Machinery Lubrication published the following top reasons that unscheduled downtime is unwelcome:

  • Production losses and schedule delays (business interruption)
  • Lost revenue and profit (unhappy management/ownership)
  • Promised delivery dates are missed (unhappy customers)
  • The blame game and damaged relationships between operations and maintenance (morale issues)
  • Hurried (botched) repairs cause future problems (cycle of despair)
  • The lack of available replacement parts and skilled trades prolongs the downtime interval
  • Repairs are at a “cost premium” due to rushed parts purchases, use of overtime labor and collateral damage
  • Scheduled “proactive” tasks are replaced by chaotic reactive tasks (leads to future problems)
  • Increased work pressure and job stress (job satisfaction issues)
  • Safety risks from rushed work, unskilled work, inferior parts, cutting corners, job stress, etc.

Alone, any of these demonstrates the value and ROI of an Oil Purifier.


Benefit #4: Better machine performance

The productivity of a company depends on how well the equipment runs.  When lube and hydraulic fluids are correctly maintained, it elevates machine health.  This results in better performance, higher availability and productivity.  It also promotes a safer work environment and a smaller environmental footprint.  On the other hand, contaminated lube and hydraulic fluids lead to derated capacity, sluggish operation, hydraulic control issues and other performance issues.  Plant Services’ surveys indicate that one of the energy industry’s most important metrics is “return on capital employed,” which correlates with rotating equipment performance.  This suggests that if rotating equipment is underperforming due to contaminated lube or hydraulic fluid, investment in an Oil Purifier may significantly and favorably impact key business metrics.

These and other benefits unique to every plant offer ample, quantifiable justification for capital investment in an Oil Purification System.  If capital is tight, rental units are available to protect machines through a budget cycle.  There are many sizes and features for consideration, making it possible to find a system that suits any needs or budget.


How To Evaluate Oil Purifiers

With many Oil Purifiers available in the market, it is essential to understand the purification methods and how to evaluate them.  The most important characteristics will determine whether this investment meets your expectations.  Doing some homework and making an educated decision is vital.  The crucial machine attributes are operational complexity, reliability, and oil processing performance.  The best Oil Purification Systems have these seven characteristics:

  1. Effectively remove all forms of water, gases, and particulate from oil without degradation or additive depletion
  2. Require minimal operator attendance to start, stop and run the unit
  3. Offer adequate, simple and convenient monitoring and control
  4. Require minimal scheduled or routine maintenance
  5. Operate at full capacity over the entire range of application conditions, including oil temperatures, pressures and viscosities, piping configurations, and environmental conditions (including sound levels)
  6. Produce minimal environmental footprint
  7. Operate with minimal energy and utility requirements

The best way to evaluate these essential qualities is to compare systems with a full-scale, onsite trial.  Nothing beats a test drive.  In this scenario, ensure that a knowledgeable factory or distributor representative is onsite during the trial to answer questions, train and assist the test personnel.  It would also be beneficial to have the operations and maintenance staff participate and provide input in the evaluation.

The next best alternative is to request a copy of the O&M manual.  A thorough review of this document with the previously mentioned attributes in mind can provide helpful information.  For example, it will likely contain the following:

  • A list of operational limits
  • Important installation requirements
  • Detailed start-up, running and shutdown procedures
  • Component maintenance requirements
  • Critical safety, environmental and hazard information

Sales and marketing material often omit much of this, but it can be found in technical documentation usually provided after ordering machines.  Feel free to request additional documentation, data and drawings.  Sales personnel should be able to help with this and provide valuable contextual information.



As you can see, an Oil Purification System can benefit any industrial plant that relies on lubricated or hydraulically operated machinery.  Fluid health is critical to machine health.  Industrial data suggests that the health and reliability of the machinery used by a business correlate to productivity, profit, safety and environmental metrics.  Consider the impact that could be realized by making a wise investment in an Oil Purification System.

Start your research now and consider companies like PowerFlow Fluid Systems, offering decades of experience designing and building the best Oil Purification Systems.  Visit our XLP Series product page and request a quote.  https://www.pwrfs.com/product/lube-hydraulic-oil-purifiers/

PowerFlow Fluid Systems supports industrial sustainability with innovative and environmentally responsible solutions for optimizing the performance of virtually all fluid systems throughout the plant.