There are hundreds, if not thousands, of applications for hydraulic technology across nearly every industry. Hydraulic actuators can achieve results that their pneumatic and electro-mechanical counterparts cannot. This is due to their use of incompressible fluids to transfer vast amounts of mechanical power. However, this fluid is vulnerable to contamination, which can compromise the functionality of the machinery it is used in. For this reason, hydraulic components require filtration systems to operate effectively.
With such a wide range of machinery depending on hydraulic technology to operate, it’s no surprise that there are also dozens of different types of filtration systems, each able to withstand a different level of pressure. In the following post, we’ll discuss common pressure ratings for hydraulic filters, how these ratings work, and what makes them so significant for the safe and optimal performance of hydraulic systems.
Hydraulic Technology: The Basics
Hydraulic systems utilize pressurized fluid to achieve power transfer. They are taking advantage of a scientific law known as Pascal’s Principle (Pressure = Force/Area). Usually, the fluid used is a mineral oil of some type; however, any incompressible liquid, including water, will do the job. Regardless of what medium is used, the fluid is pressurized by a flow restriction, which in turn applies equal pressure to all elements of the container it’s in. This pressure provides mechanical power that generates motion for the moving parts of the machinery.
Why Is Filtration Required?
Some of the most powerful machines in the world utilize hydraulic technology, including construction cranes, aircraft, and many others. While they are built to handle incredibly heavy workloads, even these heavy-duty hydraulic systems are made up of sensitive components that are vulnerable to contamination.
Over time, dirt, debris, rust, and other foreign materials will begin to accumulate in hydraulic fluids. Even new fluids are not free of contamination and should be cleaned before use. Regardless of their origin, contaminants can damage the sensitive elements of the machinery, causing wear and tear that reduces efficiency and eventually necessitates costly repairs. They can also prevent the machinery from achieving its maximum power, hampering the overall effectiveness of the entire operation.
A filtration system in a hydraulic system removes contaminants, improving the efficiency of the machinery while also reducing maintenance costs.
Pressure Ratings: Why They Matter
Since hydraulic machinery uses fluid pressure to generate force, each of the different components of the system must be built to withstand pressure. This includes the filtration systems. However, exactly how much pressure they can tolerate depends on the type of filter and where it is located within the system. Different filtration systems are not interchangeable, and a design that works for one system will not necessarily work in another. For that reason, hydraulic filtration systems are given pressure ratings so that operators can ensure they are used correctly to keep the machinery operating within the safest possible parameters.
Operating Pressure, Burst Pressure, and Collapse Pressure: What They Mean
When discussing pressure ratings, it’s important to understand that there are three measurements used. The first is operating pressure. This is the range in which the machinery should be operated regularly. That is, under normal operations, it should not be allowed to go above this amount. The burst pressure rating is the pressure level at which the machinery is expected to rupture. Note that there is always a buffer between operating pressure and burst pressure. This means the machine will not likely break down if it goes slightly over its safe operating pressure rating—at least not immediately or catastrophically.
Hydraulic filters are not just vulnerable to issues involving high pressure. If the differential pressure across the filter gets too high, this can also compromise them. This is referred to as the collapse, or crush, pressure and is rated based on the pressure differential (upstream vs downstream)that the filtration system can withstand.
The pressure ratings on hydraulic filters are listed in either BAR or PSI, depending on their country of manufacture, and are usually printed on both the equipment itself and in the operating manuals.
High-Pressure or Low-Pressure Filters?
Selecting the correct filtration system for your system requires determining if you need a high-, medium-, or low-pressure filter. Different filtration systems are optimal for different systems, so it’s crucial to understand what your specific needs are.
Low-pressure filters are installed in the return line of the hydraulic system. This location within the machinery means the filters are not required to withstand great amounts of pressure, so they are generally less costly to install. They are best for removing larger contaminants from the system, with higher-pressure ratings being needed for smaller bits of debris. Their maximum-pressure rating is usually around 150 PSI.
Medium-pressure filters are constructed to be installed inline in the hydraulic system and can remove smaller contaminants. Commonly rated from 500 to 1,200 PSI, they are best for mid-level pressure needs.
High-pressure filters are the most expensive and most sensitive filtration systems for hydraulic technology. Anything rated over 1,200 PSI is considered a high-pressure filter, with some of them rated as high as 7,000 PSI. These types of high-pressure filters are usually high crush and in some cases, they do not include a bypass. Like medium-pressure filters, they are located inline. High-pressure filters are best for the most sensitive components, which require fine particles to be removed from the hydraulic fluid.
Ensuring You Have the Best Filtration System for Your Equipment
It’s always a good idea to consult with the manufacturer of the equipment you are using to ensure your filtration system is optimal for your needs. Since each machine is different, you may benefit from a custom filtration system from a company that specializes in them, such as Aberdeen Dynamics. Wherever you source your filters, make sure that your machinery is always operated within the safe pressure ratings to achieve optimal results and ensure safety.
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