A portable pump/filter unit, PFA-1030, from Keller Products, Inc. is said to provide shops with a method for maintaining a low level of extremely fine solids in multiple sumps. The unit, which can be set up at a sump quickly, pulls the cutting fluid from the sump, filters to as fine as 5 microns, and continuously returns the filtered fluid to the sump at a rate of 20 gallons per minute.
Because the fluid is not emptied from the sump during cleaning by the pump/filter unit, the machine tool is not taken offline, and the downtime and labor for manually cleaning sumps is eliminated. The cart-mounted unit contains a rugged, high flow rate diaphragm pump, which pulls the solids-laden fluid through one of the two high capacity bag filters piped in parallel. If a filter bag plugs during the run, that filter can be taken offline and the other filter placed in service by switching two ball valves so that the run need not be interrupted. The fluid with only trace solids remaining is then pumped through a polishing filter, a stainless steel housing containing 5 micron cartridge filters and returned to the sump at high flow rate. The forces of the filtered liquid discharge scours the bottom of the sump and keeps chips and fines suspended in the fluid for pickup by the inlet hose.
Because the filter bags and the cartridge filter elements are constructed entirely of plastic fibers, the metal trapped in the spent filters can be recovered by standard reclaiming methods, an important consideration when machining platinum or other precious metals.