All About Filters

WHAT DO I NEED TO KNOW ABOUT FILTERS?

Hydraulic filters play an important role in many industries from automotive to manufacturing. The right choice of filter helps protect expensive machinery, ensures equipment runs smoothly, and maintains the high quality of your end product. The wrong filter can result in equipment damage, and even entire system failures.

So how do you know your filters are getting the job done right? When it comes to filter performance, two main things to consider are capture efficiency and retention efficiency. Capture efficiency refers to how effectively a filter captures particles while retention efficiency measures how effectively a filter retains those particles. If a filter fails to effectively capture and retain particles, it can inadvertently contaminate and harm fluid systems.

Filter testing can let you know how well your filter is performing, and whether it is time to consider an upgrade. Two types of testing are the industry standard multi-pass test ISO16889 and Dynamic Filter Efficiency (DFE), a multi-pass test designed to quantify capture and retention efficiency of hydraulic and lube filters in real time.

WHAT ARE FILTER ELEMENTS?

Filter elements are designed to remove impurities and contaminants from your operating system, and ensure that contaminants don’t interfere with the functionality of your machinery. Though their types and purposes can vary greatly, there are common configurations, including cartridge filters and spin-on filters.

WHAT ARE SOME COMMON FILTER MEDIA TYPES?

Filters are made in a number of materials, sometimes in combination with one another. Let’s take a look at some of the most common types of hydraulic filter media.

Cellulose

Cellulose is a widely abundant organic polymer that’s sourced mainly from wood pulp and cotton, and is relatively inexpensive to produce. However, its lack of uniform pore structure gives it a nominal rating, which can make cellulose filters susceptible to deterioration and shedding. While cellulose can capture particles, it’s less effective in retaining them, which along with shedding can lead to damage in industrial systems.

Glass

Glass media has a uniform pore structure, which gives it the ability to capture and contain more particles than cellulose. It’s not susceptible to structural manipulation, and it is immune from shedding, so that dirt stays where it is. For this reason, glass filters are awarded absolute ratings, and are considered an upgrade to systems that have been running on cellulose filters.

Wire Mesh

Made from stainless steel, wire mesh filter media have absolute ratings, however it is more durable than cellulose, and more capable of containing particulate. Wire mesh filters are ideal for fire-resistant fluid applications, such as high temperature governor controls, steel mill hydraulics and aircraft ground support equipment.

Coalesce

Coalescing filters are designed to separate two fluids from one another in different phases, while also filtering out particulate. Common in a variety of industries, coalescing filters are available in two subtypes: liquid-liquid filters, and liquid-gas filters, Coalescing filters can bring together into large drops free and emulsified water dispersed in oil and fuels. Those large drops can then be easily removed from the oil or fuel stream. Synthetic coalescing media now replace treated paper media for superior reliability.

Resin

Resin filter media treats fluids at a molecular level by removing contaminant molecules such as acids and free radicals, that form as a byproduct of fluid degradation and oxidation. Resin filters are designed to remove specific contaminants from fluids without removing additives, which results in better fluid performance.

Non-spark Discharge

High flowing lubrication systems found in many gas turbines create a static charge that builds up on filter elements until the charge jumps to a ground source. These very high temperature events ( 1000 deg F + ) burn the oil creating varnish which collects in servo valves causing failure. Non-spark filter medias are grounded so they don't build up a static charge, which improves equipment reliability and extends fluid life.

These filters are designed to prevent spark discharge, and therefore prevent oil degradation and antioxidant additive depletion while extending fluid life.

Water Removal

Water removal filter media is designed to remove small amounts of water from hydraulic systems. Water removal filters are typically divided between two types, coalescing and absorption.

Acid and Varnish Removal

Designed to remove the contaminants that accumulate in all lubricants and lubricating fluids, and ensure smoother operating systems.

WHY SHOULD I UPGRADE MY FILTER ELEMENTS?

Upgrading your filters can improve your system, reduce damage to your machinery, and save money, while drastically improving your sustainability efforts. For more information on upgrading your filters, contact Hydrafil today.