LU86801A1 - TAP FOR COMPRESSED AND LIQUEFIED GASES - Google Patents

Description

4 * BL-4002

TAP FOR COMPRESSED OR LIQUEFIED GASES

The present invention relates to a tap for compressed or liquefied gases comprising a body containing a closure member with at least one sealing surface at the intersection of at least one inlet channel and at least one outlet channel of the gas, an external operating means connected, through the body, to said closing member to move the latter, against the action of a spring, between an open position and a closed position.

Although not limited thereto, the invention relates more particularly to taps for gas cylinders or gas pipes used eg in the manufacture of optical fibers or in the semiconductor technique, in particular for doping of these. These gases must be of almost absolute purity, since the slightest impurity, solid, liquid or gaseous, however microscopic it may be, can disturb the doping and manufacturing process of these materials. In addition, these gases can be corrosive, even toxic.

However, the mobility of certain elements in the taps provided for the conduits of this type of gas, in particular the friction between mobile elements, may be sufficient to release particles which, when these are entrained by these gases, render them unusable. It is therefore necessary that these gases, during their passage through these valves, meet as little as possible of movable elements, in particular springs or friction sealing members. In addition, these valves must be designed to eliminate, or at least minimize, any risk of leakage to the outside, especially in the case of corrosive or toxic gases.

The criteria set by the users of these valves are so high that the existing valves, in most cases, no longer meet these requirements. Therefore, the object of the present invention is to provide a new valve which fills better 2 '- · * * For this purpose, the invention provides a valve of the type described in the preamble which, in a preferred embodiment, is essentially characterized in, that the closure member is floatingly mounted between two flexible metallic sealing membranes, one of which undergoes the action of the operating means by means of an axial rod and the another undergoes the action of a spring on the opposite side to that of said closure member.

This closure member advantageously consists of two symmetrical pistons connected to each other by a rod through a throttle of the valve body at the level of said channels, these two pistons being in substantially cylindrical chambers on either side of said throttle.

At least one of said pistons is provided with a sealing surface cooperating with a seat formed by the juxtaposed edge of said constriction. In a preferred embodiment, the two pistons are provided with such sealing surfaces.

Each of the seats is preferably formed by a conical surface which opens into the chamber of the associated piston.

The sealing surfaces of the pistons can be made of soft metal or synthetic material.

The inlet channel (s) enter the valve body at the throat, while the outlet channels exit the valve body at the chambers or vice versa.

The membrane subjected to the action of a spring is preferably connected to the latter by a cylinder with a domed head.

The closing member can be guided by circular guide segments on the pistons. However, to further reduce the friction contacts, this guiding of the closure member can be ensured by a connection between each piston and its membrane, the action of which it undergoes.

V 1 3 s

This guidance can also be ensured by the positioning of the closure member between the opposite membranes, in which case the surfaces in contact with the membranes on either side thereof have complementary profiles.

Other particularities and characteristics will emerge from the description of a preferred embodiment, presented below, by way of illustration, with reference to the appended figures, in which:

Figure 1 schematically shows an exterior view of a tap and

Figure 2 schematically shows a longitudinal sectional view through this same tap.

The tap shown in FIGS. 1 and 2 comprises a body 10, for example made of stainless steel or brass, onto which is screwed a head 12 containing a means for operating the tap. A base 14 closes the lower part of the body 10.

In the example shown, the valve body 10 comprises a radial inlet channel 16, a radial outlet channel 1 8 in the extension of the channel 1 6 and a second radial outlet channel 20 disposed perpendicularly to the channels 16 and 18.

Figure 2 shows the details of the construction of a preferred embodiment of this valve. As shown in this figure, the body 10 is traversed by a bore with several recesses and which are presented symmetrically with respect to a central annular constriction 28 which is located between two chambers 22, 24 substantially cylindrical and symmetrical on the one hand relative to the other. The inlet channel 16 opens in an axial channel 26 connecting the chambers 22 and 24 through the throttle 28. The two outlet channels leave from each of the chambers 22, 24, in the example shown, the channel 18 leaves chamber 24, while channel 20, not visible in FIG. 2, leaves chamber 22.

The closing member is constituted by two symmetrical pistons 30, 32 located respectively 4 • Js

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in chambers 22, 24 and interconnected through the axial channel 26 by a rod 34.

The inner faces of the pistons 30, 32 have sealing surfaces which, in the example shown, consist of O-rings 36, 38 made of synthetic material, such as Kel-F (trademark) and which can be held in place for example by means of beads provided on the rod 34. Instead of providing O-rings, it is also possible to design this surface of the pistons as a conical sealing surface of soft metal. The annular surfaces of the constriction 28 located opposite the pistons 30, 32 form the seats thereof and, for this purpose, are preferably designed as a frustoconical surface opening towards each of the chambers 22, 24 whose they form the background.

This central compartment of the tap 1 0 formed by the two chambers 22, 24 and the channel 26 is closed on either side by two flexible metal membranes 40, 42. The upper membrane 40 is wedged by its peripheral region between an annular rim inside the body 10 and a substantially cylindrical socket 44 screwed into the upper part of the body 10. The head 12 is, in turn, screwed into this socket 44.

In the example shown, this head 12 comprises pneumatic means for operating the tap. To this end, the head 12 is designed as a cylinder in which slides a disc-shaped piston 46 which is connected by means of an axial rod 48 passing through the head 12 and a cable gland 50 to the membrane 4 0.

The lower membrane 42 is also stretched by its peripheral part between an inner rim of the body 10 and a cylindrical sleeve 54 screwed into the lower part of this body 10. A base 14 provided with an air hole 62 is screwed onto the sleeve 54 and closes the lower part of the tap. Inside the sleeve 54 is a helical spring 58 taking 5 ► 4 support on the base 14 and exerting, on the opposite side, its action on the membrane 42 by means of a cylinder 60.

The head of the cylinder 60, as well as that of the rod 48, which are respectively in contact with the membranes 42 and 40, are preferably curved.

When the pneumatic control device is not actuated, the closing member constituted by the two pistons 30 and 32 undergoes through the lower membrane 42 and through the cylinder 60 the action of the spring 58, so that the piston 32 is held in its seat, while the piston 30 is raised. Consequently, the communication between the inlet channel 16 and the outlet channel 20 is open, while the passage between the channel 16 and the outlet channel 18 is closed. Conversely, when the disc 46 is subjected to pressure, the pusher 48 descends and exerts, through the membrane 40, its action on the closing member against the action of the spring 58. This maneuver applies the piston 30 to its seat, thereby closing the passage between the channel 16 and the channel 20, while the piston 32 opens the passage between the intake channel 16 and the outlet channel 18.

In the example shown, the two pistons 30, 32 are each provided with a circular segment 62, 64. However, this is only an optional measure to favor the guiding of the two pistons 30, 32 in their chamber 22, 24. It is for example possible, in order to eliminate any friction contact and to further eliminate all the risks of particles being released in the gases, by not providing these segments 62, 64 on the pistons, and simply ensure their guidance and positioning by the pressure applied to them on both sides by the membranes 40, 42 under the action of the rod 48 and the spring 58. It is also possible to make the opposite heads of the pistons 30, 32 integral with the adjacent membranes 40, 42, for example by means of welds or rivets.

6 example by means of welds or rivets.

Another means for ensuring stable positioning of the pistons 30 and 32 between their membranes 40 and 42, is to profile the surface of their head in a manner complementary to the profile of the opposite surfaces of the rod 48 or of the cylinder 60. In the example shown these surfaces being curved, it would suffice to provide concave heads for the pistons 30 and 32.

In the example shown, the valve is operated pneumatically. Although this is an advantageous solution, especially when the gases are toxic and corrosive, it is possible to provide other means of operation, for example mechanical, electromechanical, etc.

The valve illustrated in the figures is used to direct the gas either into the outlet channel 18 or into the outlet channel 20. In other words, there is no closure. However, it is also possible to provide only one outlet channel, for example channel 18. The tap ensures, in this case, either the opening of the passage to channel 18, or the closure of this passage. also possible to reverse the functions of the inlet and outlet channels.

It is also possible to provide a central position for the closure member, in which, for example, the inlet channel can feed two outlet channels. To this end, it suffices to provide, for example inside the spring 58, a means of limiting the compression movement of this spring.

It should be noted that the term "membrane" used in the present application must be understood in its broadest sense, including in particular bellows membranes.

Claims (12)

1. Tap for compressed or liquefied gases, comprising a body (10) enclosing a closure member with at least one sealing surface at the intersection of at least one inlet channel (16) and at least one gas outlet channel (18), an external operating means (12) connected through the body (10) to said closure member to move the latter against the action of a spring (58) between a position of opening and a closed position, characterized in that the closing member is mounted, in a floating manner, between two flexible metallic sealing membranes (40, 42), one of which undergoes the action of the operating means ( 12) by means of an axial rod (48) and the other of which undergoes the action of a spring (58) on the side opposite that of said closure member. 2. Tap according to claim 1, character ized in that the closure member consists of two symmetrical pistons (30, 32) connected together by a rod (34) through a throttle (28) of the body (10) of the tap at said channels (16, 18) and in that the two pistons (30, 32) are located in chambers (22, 24) substantially cylindrical on either side of said constriction (28). 3. Tap according to claim 2, characterized in that at least one of said pistons (30, 32) is provided with a sealing surface cooperating with a seat formed by the juxtaposed edge of said constriction (28). 4. Tap according to claim 2, characterized in that the two pistons (30, 32) are provided with a sealing surface (36, 38) each cooperating with a seat formed by the juxtaposed edge of said constriction (28). 5. Tap according to one of claims 3 or 4, characterized in that each seat is formed by a frustoconical surface which opens in the chamber of the associated piston. "* Y * m t" 8 6. Tap according to any one of claims 3 to 5, characterized in that the sealing surfaces are made of soft metal. 7. Tap according to any one of claims 3 to 5, characterized in that the sealing surfaces are made of synthetic material. 8. Tap according to any one of claims 2 to 7, characterized in that the inlet channel (s) (16) penetrate into the body (10) of the valve at the throttle (28) and in that that the outlet channel (s) (18, 20) leave the body (10) of the tap at the level of the chambers (22, 24) or vice versa. 9. Tap according to claim 1, character ized in that the membrane (42) undergoing the action of a spring is connected to the latter by a cylinder (60) with a domed head. 10. Tap according to any one of claims 2 to 9, characterized in that the guiding of the closing member is ensured by circular segments (62, 64) on the pistons (30, 32). 11. A valve according to any one of claims 2 to 9, characterized in that the guiding of the closing member is ensured by a connection between each piston (30, 32) and its membrane (40, 42) of which it undergoes the action. 12. Tap according to any one of claims 2 to 9, characterized in that the guiding of the closure member is ensured by its positioning between the opposite membranes (40, 42) and in that the surfaces in contact with the membranes (40, 42) on either side thereof have complementary profiles.