Self purge filtration apparatus for discharge to subatmospheric conditions

摘要

A self-purging filtering apparatus having a pressure vessel connected for discharging clean filtrate to subatmospheric pressure at a pump inlet. Actuators connected to an outwardly extending rod move a wiper piston to scrub the upstream side of an annular filter media element. The piston moves a main valve member to isolate a purge chamber from the filtering chamber. Remotely operated valves control flushing of the purged chamber. The main valve has a bleed valve to provide pressure equalization for facilitating main valve movement.

主权项

1. Apparatus for self-purging a filtration unit for use in a pressurized fluid system of the type having the filtration unit disposed on the suction side of the fluid system comprising:
(a) a pressure vessel having a bulkhead therein defining on one side a filtration chamber and on an opposing side thereof a purge chamber, (b) an annular filter media element disposed in the filtration chamber; (c) a process fluid inlet in the filtration chamber communicating exclusively with an upstream side of the annular filter media element; (d) a process fluid outlet in the filtration chamber communicating exclusively with a downstream side of the filter media element; (e) a piston disposed in the interior of the annular filter media element and including wiping surfaces thereon for wiping debris from the upstream side of the filter media element, the piston operable for movement along the axial length of the filter media element; (f) an elongated operating member connected to the piston and extending outwardly through a wall of the pressure vessel for effecting the movement of the piston; (g) actuator means connected to the elongated operating member operable, upon selective actuation, to effect the movement of the operating rod and piston; (h) a flushing fluid inlet and a drain outlet formed in the purge chamber; (i) a remotely operable flushing valve connected to the flushing inlet; and, a remotely operable drain valve connected to the drain outlet; (j) a main fluid passage formed through the bulkhead; and, a main valve member attached to the piston and operable to open and close the fluid passage with the movement of the piston; and (k) a bleed passage and bleed valve provided through the main valve member, wherein upon movement of the piston towards the fluid passage, the main valve closes the fluid passage and thereafter the bleed valve closes the bleed passage sequentially, and subsequently, upon movement of the piston away from the fluid passage, the bleed valve and bleed passage are first opened and the main valve and fluid passage opened sequentially.