FILTER AND METHOD OF FILTERING A FLUID

A filter comprising means defining a first chamber; means defining a second chamber; means defining a third chamber having an inlet port communicating with an outlet port of said second chamber, an outlet port communicable with a fluid line and a filter medium disposed therein between said inlet and outlet ports thereof; a piston having a head portion disposed in such first chamber, cooperating with such first mentioned means to provide a first variable chamber communicating with a port and a second variable chamber communicating with a port, and a rod portion received in the second chamber provided with a length sufficient to unobstruct an inlet port of said second chamber communicating with a line pressure on the piston is in a retracted position, allowing fluid from the fluid line to flow into the second chamber, and to obstruct such inlet port of the second chamber when such piston is in an extended position; a valve having an inlet port communicable with such fluid line and a pair of outlet ports operative to alternatively communicate such inlet port thereof with one of the ports of the variable chambers and the other of such ports of the variable chambers with the outlet port thereof, and the inlet port thereof with the other of the ports of the variable chambers and the one of the ports of the variable chambers with the outlet thereof, to reciprocate the pistons; and means responsive to the reciprocation of the piston for effecting the operation of the valve to alternatively communicate the fluid line with one of such variable chambers, whereby upon reciprocation of the piston, fluid will be drawn from the fluid line into the second chamber and expelled therefrom and through the third chamber to be filtered.