31 Aug 2022

Oil-water emulsion fluid filtration

Oil-water emulsion filtration

The post of this month is dedicated to the topic of oil-water emulsion fluid filtration, as these special fluids, used in some specific hydraulic applications, require equipment specifically designed to run with water.
This technical focus will explain what water-based fluids are and what characteristics the hydraulic components that come into contact with these substances must have.

What are oil-water emulsion fluids?

The majority of hydraulic systems run on petroleum oil, but there are many applications, such as furnaces, forges, steel mills and welding operations, where also a little leak could ignite with disastrous results.
For these applications, fire risk limits the use of flammable hydraulic fluids and this is the reason why a number of fire-resistant fluids have been developed, maintaining oil as the main fluid and adding a percentage of water into the oil (emulsified).
There are also some other common uses of fire-resistant hydraulic fluids that are less obvious.
For example, many tractors use them because the engine’s exhaust manifold can become hot enough to ignite petroleum oil.

Oil-water emulsion fluids classification

The International Standards Organisation (ISO) recognises four major groups of fire-resistant hydraulic fluids (FRHFs) based on their chemistry:

  • HFA for high-water containing fluids
  • HFB for invert emulsions
  • HFC for water glycols
  • HFD for water-free fluids, including synthetics

The main oil water emulsion fluids used in hydraulic applications are HFA and HFC.

HFA hydraulic fluids are safety hydraulic fluids with high water content (>90%) and widely used in steel mills, coal mines, and automated welding. These oil-in-water emulsions are similar to cutting oil emulsions used in metal machining.

HFC fluids are the most commonly used fire-resistant hydraulic fluids. This group includes water-glycol solutions,  that are prescribed for underground mining and wherever hydraulic fluid escaping under high pressure can ignite on contact with hot materials.

HFA and HFC fluids are used in very complex machines in many industries, such as metalworking, plastic molding presses and extruders. Since the hydraulic and lubricating oils used in machine tools must be absolutely effective in lubricating, it is important to remove particle pollution as much as possible, especially when processed materials have high hardness, as small particles deriving from process operations improve the risk of damage to the machine, tool and the workpiece.

Features of the filters for oil-water emulsion fluids

The correct filter to be used with oil-water emulsion fluids is zinc-free, to avoid any corrosion problems, and must be made in stainless steel or nichel plated steel.
In case of aluminum filters, they are subjected to anodising process.
The filer elements are made in stainless steel wire mesh filter, as FormulaUFI.WEB, with single or multiple layers, in order to catch the coarse particles, and in fiberglass media combination for the finest particles, as FormulaUFI.MICRON.

Main benefits of oil-water emulsion fluids correct cleaning

The selection of the correct oil-water emulsion filter is fundamental to reach the following targets of the hydraulic system:

  • Maintaining the fluid at the required cleanliness condition
  • Extending water-glycol fluid life, protecting the environment
  • Reducing pump and component wear
  • Improving machine efficiency
  • Minimising downtime
  • Improving the quality of the machined surface

UFI Filters Hydraulics is a specialist of hydraulic filtration and hydraulic fluids.
For this reason, UFI can provide several solutions for oil-water emulsions filtration both from its standard catalogue and from the wide range of interchangeable filter elements.
Furthermore, UFI Filters Hydraulics can design specific solutions to meet any specific fluid cleanliness requirement.
Contact our Sales Team for any further support or information.