One of the most important pieces of equipment in many different industries is the filtration system. Within each filtration system are a number of moving parts, which must all work together to ensure the system operates efficiently. Two parts that rely on each other the most are pumps and strainers. As the pump works, the strainer is in place to capture debris to ensure the pump can continue to function as designed.
Definition of Hydraulic Pump Strainers
Typically, when one refers to a hydraulic pump strainer, they are referring to a mesh strainer that is used as a filter at the pump inlet. The purpose of this strainer is to filter contaminants out of the hydraulic fluid as it approaches the suction side of the pump. These relatively coarse filters (about 140 microns) screw onto the pump intake, which is located inside the hydraulic reservoir.
Why Strainers Are Important to Pumps
Like we said above, the main purpose of a strainer is to filter out any solid contaminants from hydraulic fluid. If contaminants are left unfiltered, they can damage components of the pump. When the pump is damaged it can lead to lower system efficiency and a shortened lifespan.
That being said, picking the incorrect strainer for your system can also damage the pump. When selecting a strainer, it’s important to first consult the manufacturer recommendations. You also need to ensure you’ve selected the right sized filter, and one that meets your systems pressure and flow requirements. If your strainer fails to meet those requirements, you could potentially cause irreversible damage to your system.
Where to Position Your Strainer
The positioning of your strainer first and foremost depends on the type of strainer your system requires. The two most common types are pump suction strainers and inline filters. Pump suction strainers are a coarse mesh strainer that is used to collect large participles from entering the pump. They are installed at the suction inlet of the pump. Inline filters, sometimes called return line filters or spin-on filters, are installed in the fluid return line. This filter allows for a finer filtration of particles than the pump suction strainer and results in a highly efficient filtration system. Inline filters are not installed on the suction side of the pump because this can cause pump failure from high differential pressure.
Most pumps are designed to handle some number of solids, and the manufacturer can advise you on what size particles your pump can handle and may even have a suggestion on what filtration type is best for the system. Ultimately, the positioning of your strainer will depend on what type of system you have and how fine of a filtration you require.
When Strainers are Unnecessary
While the strainer is an important part of a filtration system, there are instances where strainers are unnecessary. If the hydraulic fluid being placed into the system has already been filtered, it is unnecessary for it to be filtered again within the system. Additionally, some new hydraulic systems do not even require a strainer as the updated design minimizes the chance of debris. Though, if proper maintenance isn’t done on the system you could still experience pump damage.
Selecting the Right Strainer
There’s no other way to argue it: strainers are important to a pump system. It’s the choice of a strainer and the positioning of that strainer that can be up for debate sometimes. If you’re questioning where to place a strainer in your system, or what strainer to use, first consult the manufacturer for their recommendations. If you still have questions after that, consult a qualified suction strainer/filter designer.