Fluid handling – Processes – Involving pressure control
Reexamination Certificate
2000-02-28
2001-04-03
Rivell, John (Department: 3753)
Fluid handling
Processes
Involving pressure control
C137S514700, C251S054000
Reexamination Certificate
active
06209561
ABSTRACT:
FIELD OF THE INVENTION
This invention relates in general to valves and in particular to an emergency pressure relief valve that relieves a pressure of a system fluid by entering an open position and then by returning to the normally-closed position following a delay period.
DESCRIPTION OF RELATED ART
In a fluid transport system having a system fluid with a pressure that varies, it is often desirable to relieve or lower the pressure of the system fluid if the pressure reaches an unacceptably high level. The most common way of relieving these high pressures is by use of an emergency pressure relief valve. The emergency pressure relief valve, which is in fluid communication with the system fluid, is designed to detect an unacceptable pressure level and relieve the pressure by opening the valve and allowing the system fluid to escape the system line.
A problem sometimes develops in the use of these valves in systems that can experience rapidly growing pressures, especially with high flow rates. For example, in certain oil and gas well drilling operations, high pressure drilling mud is pumped down the well to cool the drill bit and circulate cuttings to the surface. Large high pressure reciprocating pumps at the surface pump the liquid through flow lines leading into the well. In these systems, the pressure in the system lines can rapidly become unacceptably high unless an emergency relief valve very quickly relieves the pressure,
A typical emergency pressure valve for use in one of these systems includes a housing having an inlet port and an outlet port. The inlet port is connected to the system line. A valve member is located within the housing that is capable of moving between an open position and a closed position. In the open position, fluid communication is allowed between the inlet port and the outlet port. In the closed position, the valve member sealingly engages a portion of the housing, thereby preventing fluid communication between the inlet port and the outlet port. The valve member is biased such that it remains in the closed position when the pressure of the system fluid is at an acceptable level. As the pressure rises above an acceptable level, the valve member moves rapidly to an open position, thereby relieving the pressure by allowing the fluid to flow out of the outlet port of the valve.
In some relief or pressure regulating type valves, the spring simply snaps the valve back closed after the pressure returns below the set level. In other prior art types, which are true emergency pressure relief valves, the valve generally remains open once the maximum pressure is exceeded, and does not return by itself to a closed position once the pressure drops below the set level. For example, one type employs a rupture disk wherein the disk has to be replaced after it is ruptured due to the pressure exceeding the maximum level. Replacing the rupture disk can be time consuming and requires shutting off fluid pressure to the emergency relief valve. In another emergency relief type, a manual reset feature requires an operator to mechanically reset the valve once the valve has moved to an open position. Valves of this type typically use a valve member that is biased into the closed position by a mechanical spring. As the pressure of the system fluid rises to an unacceptable level, the valve member moves to an open position. Once it reaches the open position, the valve member is locked until an operator manually resets the valve, allowing the valve member to return the closed position. The problem with this type of valve is that it requires extensive operator monitoring. Additionally, because the valve will not return to a closed position until manually reset, once the valve is opened, the system fluid will continue to be expelled from the valve even if the pressure returns to an acceptable level.
BRIEF SUMMARY OF THE INVENTION
The emergency pressure valve according to the present invention solves the problems associated with the prior art. The emergency pressure valve of the present invention includes a piston that is connected to one end of the valve member. The piston is disposed within a pressure chamber in the housing, the piston defining an upper chamber and a lower chamber within the pressure chamber. The piston and the valve member are adapted to move together from the open position to the closed position. The valve according to the present invention uses a control fluid such as nitrogen gas or compressed air, which is introduced into the upper chamber. The pressure of the control fluid exerts a biasing force on the piston, which pushes the piston and the valve member into the closed position. The valve member and piston move to the open position when the force exerted on the valve member by the system fluid exceeds the force exerted on the piston by the control fluid.
Unlike the prior art valves, the emergency pressure valve according to the present invention uses a delay fluid to delay a return of the valve member from the open position to the closed position. As the valve is exposed to a system fluid with an unacceptably high pressure, the valve moves from the closed position to the open position. Between the closed and open positions is an intermediate position, at which point a delay fluid is introduced into the chamber beneath the piston. The pressure of the delay fluid provides a delay force to the piston which is opposite in direction to the biasing force provided by the control fluid. As the pressure of the system fluid returns to an acceptable level, the delay fluid acts against the piston to delay the return of the piston to the closed position. As the piston and valve member return to the closed position, the delay fluid flows from the portion of the chamber below the piston. Preferably, the delay fluid travels from below the piston into the chamber above the piston by way of a check valve carried by the piston. Also, preferably the delay fluid is nitrogen gas or compressed air.
REFERENCES:
patent: 1379092 (1921-05-01), Fraccascia et al.
patent: 1889256 (1932-11-01), Lipscomb et al.
patent: 2361881 (1944-11-01), Sheppard
patent: 2506162 (1950-05-01), Metzgar
patent: 3789872 (1974-02-01), Elliott
patent: 3845876 (1974-11-01), Needham et al.
patent: 3881480 (1975-05-01), Lafourcade
patent: 3942551 (1976-03-01), Schuller et al.
patent: 4046164 (1977-09-01), Pool
patent: 4221204 (1980-09-01), Meyer
patent: 4274434 (1981-06-01), Hafele
patent: 4321945 (1982-03-01), Chabat-Courrede
patent: 4485843 (1984-12-01), Wolff
patent: 4531542 (1985-07-01), Looney
patent: 4716930 (1988-01-01), Richmond et al.
patent: 5441072 (1995-08-01), Indey et al.
patent: 5443088 (1995-08-01), Hoch et al.
patent: 5685334 (1997-11-01), Hagan
patent: 5787926 (1998-08-01), Mukumoto et al.
Reset Relief Valves brochure; Harrisburg, Inc.; 1982.
Retsco Inc.; Valve illustration; Aug. 1992.
An Introduction to Rupture Disk Technology catalog; BS&B; 1994.
Emergency Relief Valve brochure; SPM; Apr. 1997.
BJ 285959; Popoff Valve information; BJ Services; undated.
Kugelev Vladimir S.
Matzner Mark D.
Bracewell & Patterson LLP
Bradley James E.
Rivell John
SPM Flow Control, Inc.
LandOfFree
Emergency pressure relief valve does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Emergency pressure relief valve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Emergency pressure relief valve will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2506178