The PRAB candle filter is a 1-micron filtration unit that offers protection of equipment and processes through fine particulate removal from spent oil and coolant. The candle filter is specifically engineered for EDM, tungsten carbide tool and cutter grinding, honing and precision grinding applications. The superior fluid removal after the purge cycle in the candle filter affords 85 percent less maintenance over other filtration methods with comparable particle retention, the company says. For most machining and grinding applications, this means changing the sludge bag every 4 months versus every 2 weeks.
The candle filter uses a long-lasting candle-like filter element that is composed of thousands of thin discs that are compressed tightly by a spring. When dirty fluid passes through the tiny gaps between the discs, all particles 1 micron and larger are trapped on the outside edges of the filter element. The filter is automatically cleaned by a rapid backwash cycle. This cycle uses air to blow out particles trapped on the discs, and then purges them into a sludge-collecting basket. The candle filter offers flow rates ranging from 13 to 80 gpm and can be equipped with an integral chiller for those applications where temperature control is important. The temperature variance with the chiller is between 1° and 2° F.