Fluid handling – Systems – With flow control means for branched passages
Reexamination Certificate
2002-05-02
2003-11-18
Walton, George L. (Department: 3753)
Fluid handling
Systems
With flow control means for branched passages
C134S098100, C134S099100, C134S16600C, C134S171000, C137S240000, C137S597000, C137S015040, C141S066000, C062S050700
Reexamination Certificate
active
06648021
ABSTRACT:
The present invention relates to a gas control device for use with a container of compressed gas, and to a method of supplying gas from such a container.
The term gas encompasses both a permanent gas and a vapor of a liquefied gas. Permanent gases are gases which cannot be liquefied by pressure alone, and for example can be supplied in cylinders at pressures up to 300 bar g. Examples are argon and nitrogen. Vapors of liquefied gases are present above the liquid in a compressed gas cylinder. Gases which liquefy under pressure as they are compressed for filling into a cylinder are not permanent gases and are more accurately described as liquefied gases under pressure or as vapors of liquefied gases. As an example, nitrous oxide is supplied in a cylinder in liquid form, with an equilibrium vapor pressure of 44.4 bar g at 15° C. Such vapors are not permanent or true gases as they are liquefiable by pressure or temperature around ambient conditions.
The conventional approach to handling gas from high pressure cylinders is to use a number of discrete components fitted to the outside of the cylinder to control such functions as pressure, flow, gas shut-off, and safety relief. Such arrangements are complex and bring problems of leaks, dead space, and numerous joints, giving difficulty in product quality and purity. Often the assembly must be enclosed in a gas cabinet which may need to be large and therefore expensive.
Compressed gas cylinders are used in a wide range of markets. In the low cost general industrial market, current standard cylinder valves are very cheap, but there is a requirement for additional functions to be built into the valve to give customers added benefits, such as direct pressure control and flow control in medical applications. In the higher cost end, such as electronics, there is a need to eliminate the problems associated with corrosion, contamination, and human exposure when making and breaking connections to the gas container, when using high purity corrosive, toxic and pyrophoric electronic speciality gases.
An example of these difficulties arises in the refilling procedure for a gas cylinder. Normally cylinders contain high pressure gases which are usually controlled by a simple shut-off cylinder valve (with a built-in rupture disc in the USA). Usually the gas will be used at a pressure substantially lower than that in the container, and the user will connect in the circuit a pressure reducing means such as an expansion valve. When there is a need to refill the gas cylinder, the shut-off valve on the cylinder is closed and the high pressure circuit is disconnected. This make and break at the high pressure of the cylinder gives the possibility of leakage and contamination. Attempts have been made to overcome this by refilling without making the high pressure disconnection.
In EP-A-0 275 242 (AGA AKTIEBOLAG) published on Jul. 20, 1988, there is disclosed an integrated cylinder valve control device intended for use primarily in gas therapy and intended to be permanently connected to a gas cylinder and surrounded by a protective cup fixedly mounted to the cylinder. The valve has a valve housing with a connection socket for the gas cylinder, and a residual gas valve and a non-return valve. The control device further includes a regulator disposed in the valve housing and operative to reduce the cylinder pressure to suitable working pressure, a shut-off valve for the gas, a quick coupling device for connection of a consumption conduit, a device for connection of a gas replenishment conduit to the cylinder, and a device for indicating the gas content in the cylinder.
In EP-A-0308875 (Union Carbide Corporation) published on Mar. 29, 1989 there is disclosed a valve-regulator assembly for rendering a high pressure gas source compatible with lower pressure equipment, the valve regulator being sealable or remote from the high pressure gas source enabling recharging at high pressure. In one embodiment, a single outlet is used for a low pressure outlet, after pressure has been reduced by a regulator, and the same outlet is used with an adaptor to recharge the cylinder. When the adaptor is used, closure means on the adaptor plug moves the regulator to a fixed position sealing off gas flow from the main conduit without regard to the gas pressure otherwise acting on the regulator. Recharging of the cylinder then takes place through the adaptor. This enables complete shut-off of high pressure gas before recharging, so as to avoid make and break at high pressure.
A similar device is disclosed in U.S. Pat. No. 5,033,499 (Patel et al) published on Jul. 23, 1991. A pressure reducing valve is mounted directly on a high pressure gas cylinder. When a standard adaptor is inserted in the outlet and a control handwheel is opened, gas is available at the outlet at a required low pressure, for example a maximum pressure of 200 bar. When a special filling adaptor is inserted in the outlet, the cylinder can be refilled to its maximum pressure of 300 bar. The special filling adaptor has a seal which inhibits gas flow from a chamber in the valve assembly via a passage in the assembly to the surrounding atmosphere. This in turn inhibits a piston moving downwardly to close the inlet of the pressure reducing valve as would be the case in normal service.
However these prior disclosures provide only limited function in the body of the assembly, namely normal low pressure regulation by manual control, and/or the ability to refill. Further functions required by the user are provided by discrete components joined in the usual way to the low pressure outlet.
Attempts have been made to provide for a number of different functions to be carried out by components mounted directly on the head of a compressed gas cylinder. In U.S. Pat. No. 5,086,807 (Lasnier et al/L'Air Liquide) published on Feb. 11, 1992, there is disclosed a pressure reducer comprising a pressure reducer body including oppositely disposed bores for mounting inlet and outlet connecting devices, and the outer end of another bore defining a high pressure chamber in which the regulating valve is mounted. The pressure reducer body is adapted to receive a connecting device for a high pressure manometer defining a rest for a spring of a regulating valve which includes an annular truncated lining in which is force fittingly engaged a connecting rod between the regulating valve and the piston bounding the low pressure chamber. The invention proposes an industrial type pressure reducer of a simplified design, including a high pressure manometer and a low pressure manometer.
In U.S. Pat. No. 5,127,436 (Campion et al/L'Air Liquide) published on Jul. 7, 1992, there is disclosed a gas distribution adaptor and pressure reducer device for a high pressure gas cylinder. The device comprises an assembly intended to be mounted on a closure valve of the high pressure gas cylinder and comprises a manual control device operating a distribution valve in which the upstream end communicates with the closure valve, a pressure reducer and a safety device against over pressures between the distribution valve and an outlet for connection to a user circuit, as well as a manometer which measures the pressure upstream of the distribution valve.
However, yet again the number of functions provided in these devices mounted on the cylinder head is limited, and further functionality required is provided by conventional components connected to the outlet of the cylinder head control device.
In U.S. Pat. No. 5,163,475 (Gregoire/Praxair Technology, Inc.) published on Nov. 17, 1992 there is disclosed a micro panel for the delivery of gas from a supply cylinder to a tool location comprising an arrangement of valves, pressure regulator and associated components adapted to enhance the purity of the delivered gas and the safety of the gas delivery panel. The object of the invention is to provide a reduced size micro panel adapted for the control of ultra high purity hazardous gases. The panel components are arranged and ported so that the gas flow path is preferably st
George Mark Allen
Irven John
Zheng Dao-Hong
Air Products and Chemicals Inc.
McAndrews Held & Malloy Ltd.
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