Patent Application
20050109974
1. Field of the Invention
The invention generally relates to valves for pressurized tanks or other pressurized containers, e.g., pressurized gas bottles. More particularly, the invention relates to valves for pressurized containers which are commercially characterized as being “non-refillable” or “no-return” containers and which, for reasons of safety and otherwise, are not intended for re-use after their initial contents have been emptied. Valves for such containers are also often referred to in the art as “single use” valves for pressurized containers.
2. Background Of The Invention
Pressure tanks or other pressure containers are usually filled under carefully controlled conditions at a charging station and then distributed to other places for use. When empty it is intended that the containers be returned to the charging center for appropriate reuse or destruction in the case of single use containers. Unfortunately, the attractive economies of refilling containers at points of use or otherwise repressurizing them under less than carefully supervised conditions has resulted in the introduction of impurities or inferior refills and, more seriously, in injurious explosions. The reuse of pressure containers is highly objectionable for many reasons which relate to safety.
So-called “non-refillable valves” are well known in the prior art. Specific examples of known valves include valves of the type described in U.S. Pat. No. 4,543,980, to van der Sanden, issued Oct. 1, 1985; valves of the type described in U.S. Pat. No. 4,573,611, to O'Connor, issued Mar. 4, 1986, and the various prior art valves described in the aforementioned patents.
Non-refillable valves desirably fill the following requirements: (a) the need for a dual purpose manufacturing process that uses a single basic valve design to enable both refillable and non-refillable valves to be manufactured using essentially the same parts list, machine tools, etc.; instead of the present practice of having to execute dedicated manufacturing process for producing refillable versus non-refillable type valves (because of differing housing types that are used, different components required for valve operation, etc.); (b) the need for a valve design (both refillable and non-refillable) that utilizes a mechanically operated primary sealing mechanism (as opposed to valve designs that utilize a pressure differential to open the primary sealing mechanism) to insure seal quality while solving the other problems with known valves indicated hereinabove; (c) the need for a valve design that prevents rotation of the primary sealing mechanism in the valve housing to minimize wear, extend valve life and further improve seal quality; (d) the need for a valve design in which the primary sealing mechanism and means for controlling the opening and closing of the valve are optionally made from discrete components formed from different materials to enable the sealing mechanism to be chemically compatible with the fluid contents of the container even when the controlling mechanism (means for controlling the opening and closing of the valve) is not; and (e) the need for a valve design, solving all of the aforementioned problems and meeting the aforestated needs, which is relatively simple and inexpensive, which will allow normal filling of the pressure container under proper conditions, adequate sealing of the pressure during nonuse, selective discharge of the pressure container and, in the case of the non-refillable valves contemplated by the invention, provide effective protection and prevention against improper and unauthorized filling of the container.
A new standard for disposable cylinders was published in Europe, EN 12205. One of the requirements of this standard was that the valve used in these cylinders should conform to EN ISO 13340. With certain present commercial valves, after filling the cylinder for the first time, and having shut the valve once, when we tried to refill the cylinder with helium, the filling rate was greater than 3 cm2 per hour, which does not comply with the new standard specification.
Thus, it can be appreciated that it remains desirable to have new valve designs that provide the needs discussed hereinabove and yet remain relatively simple and inexpensive to produce.
The present invention provides a valve design that utilizes a poppit that provides a seal meeting the new EN ISO 13340 standard. In accord with the present invention, a valve for a pressurized container comprises a valve housing having a central bore for communicating with the container; a port in said housing to facilitate connection of a nozzle thereto; a t-stem having a lower end with an opening; and a poppit comprising a valve seat providing the primary valve seal when the valve is closed. The poppit comprises a valve seat and a support for the valve seat, the support having a shaft that is received in the opening of the lower end of the t-stem. The valve seat is made from an elastomeric material, which can be a natural or synthetic rubber.
In one embodiment of the invention, a valve for a pressurized container comprises a unidirectional stepped valve housing, wherein said housing comprises a central bore that includes an upper portion, lower portion and a middle portion located therebetween, wherein said lower portion is narrower than said middle portion which in turn is narrower than said upper portion; a port in the middle portion of said housing to facilitate connection of a nozzle thereto; a t-stem having a lower end with a key-way, the lower end further having in conjunction with the key-way a cavity of a predetermined geometric shape; and a valve seat providing the primary valve seal when the valve is closed, wherein the valve seat has an upper portion and a lower portion, the lower portion being structured and arranged to provide the primary valve seal in cooperation with the valve housing, the upper portion having a geometry corresponding to the predetermined geometric shape for engaging with the t-stem to provide a locked assembly; the t-stem and valve seat being located in the housing and cooperating to position the valve seat for the primary valve seal. A non-refillable valve in accord with the present invention further comprises a blocking element in the lower portion of said central bore.
These and other features of the present invention and the manner of obtaining them will become apparent to those skilled in the art, and the invention itself will be better understood by reference to the following detailed description read in conjunction with the accompanying Drawings.
A non-refillable valve of the type contemplated by one aspect of the invention will be described with reference to the figures.
In this embodiment, central bore 104 in valve housing 105 has three distinct portions: upper bore portion 120, middle bore portion 121 and lower bore portion 122. In accord with a preferred embodiment of the invention, valve housing 105 is a unidirectional stepped valve housing (i.e., a valve housing that includes a central bore having two or more stepped portions each radially increasing (or conversely decreasing) as the bore is traversed in a given direction).
Traversing the valve from top to bottom, the radius of the bore in the upper valve portion 120 can be seen to be greater than the radius in middle valve portion 121; and the radius in middle valve portion 121 can in be seen to be greater than the radius in lower valve portion 122. This design can be advantageous for valve manufacturing purposes.
Non-refillable valve 100 can be attached to a cylinder expressly intended for a one fill opportunity. The attachment is typically performed by welding valve housing 105 to the container in the area marked 130 and 130a in
Non-refillable valve 100 has the following main components: t-stem 160 for controlling the opening and closing of the valve; a two piece poppit 161 including a support portion 163 and a valve seat portion 164; unidirectional stepped valve housing 105 which encloses all valve components; sealing means (such as o-ring seal 165); and nozzle (or port) 103 for filling and using the container. For extra sealing in the valve housing, a second o-ring can be used, one in each groove 166, as shown in the t-stem 160-1 illustrated in
The t-stem 160, 160-1 is used to control the opening and closing of the non-refillable valve.
The two piece poppit 161 is further illustrated in
Valve seat 164 has an interior geometry that cooperates with the end 172 of the support portion opposite the shaft 171. Near the end 172, the support portion has an integral disk 173 providing a platform for the valve seat 164. The end 172 is tapered having an angled surface 174a, 174b which extends beyond the diameter of the shat 171 to form a cap. The angled surface forms an arcuate section 175a, 175b on opposite sides of the shaft. Arcuate openings 176a, 176b are provided in the disk 173 to aid in molding the support portion 163 as an integral unit. The valve seat portion 164 is preferably symmetrical about its longitudinal axis.
Those skilled in the art will readily appreciate that alternative geometries can be employed for the components of the poppit. The depicted support portion and valve seat portion are not intended to limit the scope of the invention, but rather to illustrate a suitable shapes for effecting the primary valve seal and effecting a locking engagement.
In the embodiment of the invention illustrated in
Furthermore, according to one embodiment of the invention, valve seat 164 and support portion 163 are attached by snap-fit engagement illustrated in
The valve seat portion is made of an elastomeric material in order to provide a suitable seal meeting the requirements of EN ISO 13340. The elastomeric material can be either a natural or synthetic rubber. The material should be selected depending on the intended contents of the container on which the valve is used. A preferred elastomeric material is thermoplastic elastomer such as a styrene butadiene block copolymer, particularly modified with polypropylene, e.g. SEBS/SEPS base modified with PP where SEBS is styrene butadiene block copolymer with hydrogenated polybutadiene, SEPS is styrene butadiene block copolymer with hydrogenated polyisoprene, and PP is polypropylene. Prederably, the hardness of the elastomeric material is between about 50 to about 90 on the Shore A scale, more preferably about 60 to about 80 Shore A. In one embodiemnt for storing compressed gas at −50° C., a hardness of 60 was found to be useful.
A suitable material for a helium container is Multiflex™ G 60 A 21 BT Z3519N0104.
The supporting portion of the poppit can be any suitable material. Preferably the support portion is made of a plastic resin. A suitable material for the support portion is Zytel™ 70G33HS1L BK031R.
The non refillable valve is shipped with the valve stem in the factory pre-set full open position. The free floating nose cone is compressed and retained in the narrow upper barrel of the valve body. In this position, the valve is fully open and the evacuation and filling process is carried out in the normal manner.
In use, after the initial filling of a container having the valve of the present invention is completed, the valve is closed. Once positioned, it preferably is impossible to force the valve seat back into the factory preset open position. When the t-stem is fully closed, the nose-cone of the valve seat is forced down against the valve housing and the valve is closed for storage and transportation to the field. The valve preferably is closed to a torque value of 35 inch-pounds (3.9 N/Mtr.) using manual or automatic drivers which incorporate an automatic torque limiting device.
To use the contents of the container, the valve is manually opened in the normal manner. Because external pressure in the system being serviced is lower than the internal pressure of the cylinder, the pressure differential preferably forces the free-floating poppit off the valve housing to open the lower portion of the bore to the container and contents are discharged at the full flow rate, in the normal manner. When the desired amount of the contents has been discharged, the valve is manually closed and cylinder contents are protected until the next use. The cylinder is used in the normal way until its contents have been fully discharged.
At any time during use or after the contents have been discharged, should the cylinder be accidentally or deliberately connected to a pressure source higher than the internal pressure of the cylinder and the valve manually opened, the pressure differential preferably will instantly force the free-floating poppit back onto the valve housing to prevent the introduction of materials into the cylinder. In preferred embodiments, this automatic valve closure occurs regardless of the cylinder position.
The invention has been described in detail including the preferred embodiments. However, it should be appreciated that those skilled in the art may make modifications and variations within the scope of the present invention in light of the above teachings. Therefore, it is understood that the claims appended hereto are intended to cover all such modifications and variations which fall within the true scope and spirit of the invention.
This application claims priority from U.S. application Ser. No. 60/523,950 filed Nov. 21, 2003.
| Number | Date | Country | |
|---|---|---|---|
| 60523950 | Nov 2003 | US |
