High pressure pipeline filter: (A) is located in the export pipeline pump, have the effect that protect the pollutants enter the system. So, can the control system of pollutant concentration. Because it is high pressure head of road, but to be the pulsation of the pump and pressure shock, so the material of filter element, strength to reconsider.

　　1, air filter, is located in the tank, prevent the pollutant due to changes in the amount of oil tank with air into the tank. So the performance of the filtering accuracy should at least equal to the filter, the capacity to sufficient leeway, in case that makes the pressure inside the tank for the hole jam into a negative pressure, cavitation of pump. Pay particular attention to in the surrounding conditions.

　　2, high pressure pipeline filter: (A) is located in the export pipeline pump, have the effect that protect the pollutants enter the system. So, can the control system of pollutant concentration. Because it is high pressure head of road, but to be the pulsation of the pump and pressure shock, so the material of filter element, strength to reconsider.

　　3, vacuum oil filter: the filter is located in the pump suction pipe road, residual pollutants within the filter tank through air holes into the pollutants, have a role to protect pump. But in order to avoid the pump cavitation, must pay full attention to the pressure loss, the use of 100-200 general purpose of thick metal mesh or notched wire material. Therefore, it is not the control system of pollution concentration of filter

　　4, return filter: in system, return pipe road, its role is to put the system before the return tank or invasion of pollutants catch. So it is the most important pollution concentration control system of the most effective filter. Is low pressure pipeline, but on the running status of the transmission device, also can appear ripple impact or pressure, so, we must give full consideration to the strength of component materials,.

　　5, high pressure pipeline filter (B) : in the system, in order to protect the particularly sensitive to the pollution of hydraulic parts, to install the filter, also known as terminal filter. So it is often smaller than other filters filter size. So choose when using large capacity. In addition to element material, strength is the same as (A) to give full consideration to.

　　6, loop filter: located in loop back to the oil tank, the system of large capacity, when demand was strict cleanliness so tend to be used, even if the system is not working, can also be pollutants within the tank to capture, therefore, reduce the efficiency of pollution concentration is best. In addition to install the cooler, has the advantages of can be cooled at the same time, easy to maintenance. But need to use special pump and motor, high cost. (this article from dow water purifiers website)