Pilot operated relief valve

Claim 2

A pressure sensitive pilot valve for operating a main pressure relief valve to relieve excess product vapor pressure, having first and second stages in cascade, comprising; a valve body containing said stages and having first and second inlet ports for sensing product and main valve head pressure, respectively, exhaust and test ports; a first seat in said body in fluid communication with said first inlet port; a first stage poppet having first and second positions seated on and restricting flow through said first seat for said first poppet position, below a predetermined value of product pressure and allowing flow therethrough for said second poppet position; second and third seats in said body; a second stage plunger, having upper and lower ends, reciprocating in said housing, said upper end responsive to first stage flow and movable between said second and third seats for first and second poppet positions respectively; means fluid communicating said first seat and plunger upper end for said second poppet position; means communicating said first inlet port and second seat for a first plunger position; means communicating said second inlet port, exhaust port, and third seat for a second plunger position; guide means intermediate said first inlet and test port; a flow sensitive closure member contained in said guide means for reciprocal movement therein, said member sealing said test port or communicating means at either end of said motion; wherein fluid admitted to said test port and reaching a pressure greater than said product pressure isolates said first seat.

Claim 3

The pilot valve of claim 1 where said guide means include a fluid permeable cylinder and said flow sensitive member is a ball.

Claim 4

The pilot valve of claim 2 further comprising; a predetermined volume communicating with said plunger upper end, providing control of internal pilot product flow during said poppet and plunger movements.

Claim 5

In a two stage pilot valve having a valve body, a first stage poppet, and a second stage plunger, and utilizing reciprocal poppet motion attendant periods of valve relief and reseating operation, for relieving product vapor pressure in excess of a predetermined relief value, having a pressure operated first stage admitting product flow therethrough when product pressure exceeds said predetermined relief value, and a second stage responsive to first stage product flow, for operating a main valve and terminating product flow through said first stage, the improvement comprising; a first stage poppet comprising; a stem having a piston at one end; means mounting said stem in said body for reciprocal motion therein a shoulder, on said stem coaxial with and adjacent said piston; a seal intermediate said piston and shoulder; a seat defined by said mounting means adjacent said shoulder and coaxial said stem, coacting with said shoulder and seal to terminate poppet motion and flow through said passage during relief operation; a passage, defined by said stem and mounting means clearance, providing product flow therethrough during periods of poppet operation; a damping chamber in fluid communication with said first and second stages during periods of poppet relief operation, providing controller poppet motion; a cavity in said body for containing said first poppet; a seat defined by said cavity coacting with said piston to prevent product flow for vapor pressures less than said relief valve; and a test port in said body; means in said body, fluid communicating said test port, seat, and cavity; a product inlet in said body in fluid communication with said communicating means guide means intermediate said test port and communicating means, said guide means in further fluid communication with said test port and seat; a flow sensitive closure member contained in said guide means for reciprocal motion therein said member sealing said test port or communicating means at either end of said motion; wherein introduction of test vapor at a pressure greater than normal product pressure moves said closure member to isolate said product inlet, providing operation of the pilot without an increase in product pressure.

Claim 6

In a two stage pilot valve having a valve body, a first stage poppet, and a second stage plunger, and utilizing reciprocal poppet motion attendant periods of valve relief and reseating operation, for relieving product vapor pressure in excess of a predetermined relief value, having a pressure operated first stage admitting product flow therethrough when product pressure exceeds said predetermined relief value, and a second stage responsive to first stage product flow, for operating a main valve and terminating product flow through said first stage, the improvement comprising; a first stage poppet comprising; a stem having a piston at one end; means mounting said stem in said body for reciprocal motion therein a shoulder, on said stem coaxial with and adjacent said piston; a seal intermediate said piston and shoulder; a seat defined by said mounting means adjacent said shoulder and coaxial said stem, coacting with said shoulder and seal to terminate poppet motion and flow through said passage during relief operation; a passage, defined by said stem and mounting means clearance, providing product flow therethrough during periods of poppet operation; a damping chamber in fluid communication with said first and second stages during periods of poppet relief operation, providing controller poppet motion; a cavity in said body for containing said first poppet; a seat defined by said cavity coacting with said piston to prevent product flow for vapor pressures less than said relief valve; and a test port in said body; means in said body, fluid communicating said test port, seat, and cavity; a product inlet in said body in fluid communication with said communicating means guide means intermediate said test port and communicating means, said guide means in further fluid communication with said test port and seat; a flow sensitive closure member contained in said guide means for reciprocal motion therein said member sealing said test port or communicating means at either end of said motion; wherein introduction of test vapor at a pressure greater than normal product pressure moves said closure member to isolate said product inlet, providing operation of the pilot without an increase in product pressure.