What is the difference between a coarse diesel filter element and a fine filter element?

The primary diesel filter element is usually placed on the suction end of the fuel pump, and low resistance is required due to the small suction pressure. The main task of the coarse filter element is to protect the oil pump and reduce the burden on the fine filter element (if installed). The coarse filter element generally has a rated filtration accuracy of 10-30 microns (microns). The diesel fine filter element is generally placed between the fuel pump and the fuel pump (or fuel injector). The fine filter element will fully protect the subsequent fuel pump (fuel injector). The diesel fine filter element is placed behind the oil transfer pump, which will bear higher pressure and at the same time have a higher filtration accuracy (rated filtration accuracy is 2-10 microns).