Contamination Sources:

It is widely recognized that water and particulate contamination can degrade critical physical properties of hydraulic fluid and lead to premature wear as well as possible malfunction of hydraulic system components. 



Maintenance: during component manufacturing and overhaul, contaminants are left behind and then introduced to the aircraft when reinstalled. This can be in the form of tiny metal fragments, contaminated fluids used in acceptance testing, FOD caps missing during handling, or solvents used in the manufacturing, cleaning, or testing of the component.


Component wear during operations: although the onboard filter is designed to reduce this type of contamination, over time, fluid systems can become so contaminated that the onboard filter will just clog up quickly once installed in a heavily contaminated aircraft. Worn or shedding hoses also leave behind debris that clogs the onboard filter and contaminates the entire system. If poor onboard filtration is used, the contaminant not caught by the filter will make it downstream into valves, pumps and other components creating even more wear.  As the components wear, the wear debris makes it back to the filter element and if that debris is not captured because of poor filtration, the debris contaminant itself creates more wear. We call this loop the “chain reaction of wear”.


Ground support equipment: even in a closed system, worn system seals, system fill caps left off, or inadequate cleaning around the system fill port before connecting ground equipment allow contaminants to enter. 



Contamination Control:

A better way to manage fluid contamination, with proven benefits!


Field investigations have shown that the most common reason for used hydraulic fluid being drained and discarded is because it has become contaminated to such a degree that it could damage the hydraulic system. However, laboratory studies have determined that even though the hydraulic fluid may be heavily contaminated, its ability to perform has not been lessened.  Analysis during the laboratory phase of past Pall purification projects revealed that used hydraulic fluid retained nearly all of its required performance capabilities, i.e. viscosity, corrosion protection, etc. 


The approved methodology of returning used hydraulic fluids to spec performance, involves the removing of contaminants from fluids and revitalizing fluid additives.


By using the correct hydraulic fluid purification process for removal of water and particulates, you can maintain hydraulic fluid at the required performance specification levels and avoid pump wear, valve spool sticking, seal wear, cylinder scoring, and erosion of system components, decreased lubricity, viscosity, load-carrying ability and other degradation.


  • Purification of Hydraulic Fluids
    • Removal of water and volatile solvents
      • Prevents corrosion of hydraulic system components
    •  Removal of solid particulates/removal of air
      • Prevents hydraulic system component wear
      • Prevents cavitation, sluggish system response, hydraulic fluid degradation
  • Fluid purification methods include:
    •  Flash Distillation
    • Vacuum Dehydration    

Why choose a Purification solution?

  • The use of a certified automated hydraulic fluid purifier, optimizes processing time and eliminates the labor required to collect and analyze fluid samples
  • Reutilizing hydraulic fluid to specification performance directly relates to less new fluid procured, less fluid required to be kept in stock to meet fluid usage requirements, and less fluid required for deployments (deploy with a small amount of oil and an oil purifier vs. deploying with large quantities of oil)


  • Implementation of hydraulic fluid recycling has a significant impact on meeting pollution prevention goals, conserving natural resources, and reducing costs associated with both the procurement of new and disposal of used hydraulic fluids





With over 5000 purifiers sold world-wide, Pall brings over 3 decades of experience in providing purification solutions for nearly all industrial markets. Our purifiers help you bring hydraulic fluid to specification performance and increase operational readiness, system performance and reliability.  

Marine Fluid Purifiers

Application: Commercial Marine Vessels, Naval Submarines, Naval Surface Ships

The Pall purifier solves the problem and unlike centrifuges and coalescers, it removes both FREE and DISSOLVED water. The HNP006++YK30 variant was specifically designed to be installed on ships.

Portable Fluid Purifiers

Application: Commercial Fixed Wing, Commerial Rotary Wing, Military Fixed Wing, Military Rotary Wing

The Pall fluid purifier provides a portable, environmentally friendly solution to remove free and dissolved water, gases, solvents, and particulate contamination, and thus extend fluid and component life. It also improves system performance and responsiveness.

HNP023 Series Oil Purifier

Application: Commercial Fixed Wing, Commerial Rotary Wing, Military Fixed Wing, Military Rotary Wing

The Pall HNP023 Series Oil purifier is designed for use with small to medium oil systems, particularly where high viscosity fluids are employed, and can effectively remove 26 liters of water per day from the oil*. The purifier uses vacuum dehydration to remove 100 % free water and as much as 90 % of dissolved water. It will also remove 100 % of free and entrained gases and up to 80 % dissolved gases.

HNP076 Series Oil Purifier

Application: Commercial Fixed Wing, Commerial Rotary Wing, Military Fixed Wing, Military Rotary Wing

Water contamination promotes corrosion and fluid system component wear, resulting in reduced component life and increased maintenance costs. It also degrades fluid properties, leading to reduced lubricity and load carrying ability, oil oxidation and the resultant formation of acids, and additive precipitation. The consequences are reduced fluid service life and increased fluid procurement and disposal costs.

Mobile Water Purification Units

Application: Military and Civil

Relief agencies, military defence forces and ship operators have a need to be able to produce potable water from virtually any raw water source. Pall Corporation has developed a range of mobile, fully self contained, water treatment systems designed to produce potable water from fresh, brackish and sea water sources. The systems have an output capacity ranging from 20 to 3500 m3/day with a proven performance in demanding applications including disaster relief operations in Indonesia and New Zealand.

Features & Benefits





  • Removes 100% of free water and 80% of dissolved water in hydraulic fluid


  • Removes particulate contaminant from hydraulic fluid with 3-micron filter element


  • Wheeled GSE. Can be used in the hangar or at the line, or both


  • Utilizes vacuum dehydration instead of fluid damaging heat



  • Reduces acid formation and associated damage to hydraulic system components.


  • Improves service life of critical hydraulic components


  • Eliminates the need to replace hydraulic fluid, saving cost associated with fluid purchase, disposal, and labor to flush the hydraulic system


  • ROI in as few as seven uses


  • Eliminates time and guesswork to keep resources deployed most efficiently