Basics Of Hydraulic Filters
Hydraulic Filters
Hydraulic filters help eliminate contaminants from your hydraulic fluid when flowing through the system. Many of these particles are very small so they are not visible with the naked eye. But, that doesn’t mean they can’t bring havoc on your hydraulic system, as well as your last motor drive. At this Talk blog shop, our focus will review the basics of hydraulic filters.
The purpose of the hydraulic filter
As the name implies, the filter can “filter out” certain types of contamination. They basically cleanse hydraulic fluid when they flow through them. If a component in the hydraulic system suffers from disaster failure, it will usually introduce contamination into the system. Filters help keep the contamination quite localized to one area.
Hydraulic filter type
In a hydraulic system, there is a pressure filter, which lies in pressurized lines (as they are between pumps and hydraulic motors), and low pressure filters (aka, return. In addition to the basic classification, there are several types of hydraulic filters.
Screen filter
The screen filter is what is called: a screen made of tight woven cable. Weaving on this cable creates the size of the specified pore. The size of the pores controls the size of the particle which can be captured by the filter. An example of a screen filter will be a suction filter on the reservoir pump outlet. The suction filter has a relatively rough mesh designed to filter out rough contaminants.
Inline cartridge filters and spin-on filters
Inline cartridge filters and spin-on filters have filtering cartridges that can be replaced when clogged. Spin-on filters are usually found on low pressure returns while inline cartridge filters can be found both on pressure and return path. This may be the most common type of filter found on a concise and heavy tool.
Filter bag
With a bag filter, hydraulic liquid is forced through a cloth bag. Solid contaminants, such as rust, dirt, metal particles, etc., are trapped in the bag. This is usually limited to applications involving large volumes of fluid and are not commonly found in heavy equipment.
Filter housings
Most of these filters are contained in plastic, steel or aluminum homes. The type of housing mainly depends on the level of pressure involved. That’s why you will see a plastic or aluminum home for filters on a low pressure return path. Drainage filter case, which is a low pressure refund line filter, has an aluminum house, for example.
Filter Ratings
Filters are assessed in microns, which refers to the minimum size of filter particles designed to filter. To give you some perspective, the average human hair will be around 90 microns in diameter. According to the contamination guide for hydraulic, oil and diesel fluids by Schroeder Industries.
“Particles that cause problems in high performance, high pressure hydraulic systems are in the range of around 5 to 15 [microns].”
It’s far, much smaller than human hair, and the possibility is not visible with the naked eye. And it is a type of particle that hydraulic filters do a very good job to filter your liquid.
Other key metrics for filters are beta ratio ꞵ. The best way to explain the beta ꞵ ratio is by example: Filter with beta ꞵ 100 ratio means that for every 100 particles that enter the upstream filter on one particle will make it through the filter.
Of course, beta ꞵ ratio does not mean anything without micron ratings. If you have a 6 micron filter, you will see the values combined as β6 ≥ 100. That means filters are assessed for 6 microns, bigger or equal to beta ꞵ 100. Of 100 upstream particles or larger diameter, only one of the particles which will work through the filter. Ranking efficiency for filters is given by (ꞵ – 1) / ꞵ x 100%. The higher the beta ratio, the more efficient the filter.
Quality hydraulic filter vs. Cheap hydraulic filters
Quality hydraulic filters may seem expensive, but keep in mind that cheap filters are usually very cheap for a reason. Cheap filters can do more damage than goodness. Think of filters as an investment in the life and health of your hydraulic system, and make a wise investment!
Conclusion
Hydraulic filters are an important part of your hydraulic system. That’s why we encourage you to check and change it according to the manufacturer’s guidelines. We also want to encourage you to invest in a quality filter for your machine.
