GB2024992A - Flap Valve - Google Patents

Abstract

The valve has one or more flaps (4, 5) mounted on a shaft (2), a flap frame (1) against which the or each flap (4, 5) is sealed around its periphery when the valve is closed. The or each flap (4, 5) is mounted on at least one lever arm (6, 12) fixed to the shaft and extending outwardly of the axis of rotation thereof. The valve also includes a tubular member (14) surrounding the shaft (2) and connected hermetically at each end of the tubular member (14) to the flap frame (1) and having a lateral opening in the region of the or each lever arm (6, 12) and through which the lever arm extends, an annular seal (16) positioned between the shaft and the tubular member adjacent the or each lateral opening, a first peripheral sealing face on the or each flap, a second sealing face on said flap frame and on the tubular member, and a resilient sealing gasket on one of said sealing faces and sealingly engaged by the other of said sealing faces around its whole periphery when the valve is closed. <IMAGE>

Description

SPECIFICATION Flap Valve The invention concerns a flap valve having a flap or flaps carried on a shaft traversing the closing element and arranged to be sealed against a flap frame by resilient sealing gaskets when the valve is closed.

In nuclear technology, extremely severe requirements are laid down for the tightness of seals, along with extremely low permissible rates of leakage, in the case of spaces into which radioactively contaminated atmospheres may penetrate. The same is true of spaces and pipelines with which there is a risk that the atmosphere may be infected with viruses, bacteria or the like.

In order to satisfy the said severe requirements for sealing, a known procedure with flap valves is to use tubular gaskets which become inflated in the closed position of the flaps and so form a sealing contact with the flap frame. A loss of pressure in the gasket tube would automatically cause leakage. Tubular gaskets therefore need continuous supervision.

An object of the invention is to provide a flap valve with which the required high degree of sealing can be achieved with the use of elastic seals which are not of the inflatable kind.

According to the invention, a flap valve comprises at least one flap, a shaft on which the or each flap is carried, a flap frame against which the flap is sealed around its periphery when the valve is closed, the or each flap being mounted on the shaft by at least one lever arm fixed to the shaft and extending outwardly of the axis of rotation thereof, the valve also comprising a tubular member surrounding the shaft and connected hermetically at each.end of the tubular member to the flap frame and having a lateral opening in the region of the or each lever arm and through which the lever arm extends, annular sealing means positioned between the shaft and the tubular member adjacent the or each lateral opening, a first peripheral sealing face on the or each flap, a second sealing face on said flap frame and on the tubular member a resilient sealing gasket on one of said sealing faces and sealingly engaged by the other of said sealing faces around its whole periphery when the valve is closed.

Conveniently the flap valve has a pair of flaps mounted on the shaft at diametrically opposite positions thereon by a pair of lever arms on each flap, each lever arm extending through a respective lateral opening in the tubular member, one lever arm of each pair extending in opposite directions through respective oppositely-directed lateral openings between which there is one said annular sealing means to prevent communication between said oppositely-directed lateral openings.

The or each flap is preferably arranged to swivel on the lever arm or respective lever arm.

The or each lever arm may be mounted on a locking ring secured to the shaft.

Preferably the or each annular sealing means comprises an annular seal carrier joined hermetically at its outer periphery to the inside of the tubular member and at least one annular sealing gasket positioned between the annular carrier and the shaft.

In a preferred embodiment, the tubular member consists of part-cylindrical co-operating shells which are joined together by or within the or each annular seal carrier.

The sealing gaskets provided on or engaging the flap frame or in the annular sealing means may be either single or double.

By way of example an embodiment of a shut off flap valve in accordance with the invention is illustrated in the drawings, and is described in detail with the aid of the diagrams, in which: Figure 1 shows a plan view of part of the shut off flap valve, and Figure 2 shows a section along the line Il-Il in Figure 1.

The shut-off valve represented, also called a wing throttle, has a flap frame 1 of rectangular or square shape and in the example illustrated has a U cross-section. In the middle of the flap frame 1 there is a shaft 2 extending transversely to the direction of flow. The shaft 2 is rotatable in bearings 3 fixed to the outside of the flap frame 1.

The valve represented has two passage openings I and Il above and below the shaft 2 and two respective separate flap elements 4, 5. The flap 4 is carried by two lever arms 6 spaced apart: the arm not shown in the diagram being the mirror image of the one illustrated. The connection of the flap 4 to the lever arms 6 is effected through hinges 7 each having an axis parallel to the shaft 2. The swivelling motion of the flap 4 around the hinges 7 is restricted by a stop pin 8. The lever arms 6 are fixed to a locking ring 9 which can be tightened by a screw 10 and can be fastened to the shaft by a key 11. The flap 5 is connected to the shaft 2 in a similar way, the two lever arms 12 carrying the flap 5 being positioned nearer to the centre line 13 of the flap, than the lever arms 6.

A tubular member 14 is disposed concentrically around the shaft 2, and its ends are secured hermetically to the inner side of the flap frame 1. The tubular member 14 has oppositely directed lateral cutouts through which the lever arms 6 and 12 extend. Between the oppositely directed lateral cutouts of the tubular member 14 at each side of the centre-line 13 there is an annular seal carrier 1 5. In the example shown the seal carrier 1 5 is situated in a closed section of the tubular member 14 and is joined hermetically to the inside of that member. The sealing element 1 5 may for example be soldered or welded to the tubular member 14.The seal carrier 1 5 carries two gaskets 1 6 which co-operate with the surface of the shaft and are positioned in the seal carrier so as to work in opposition.

An annular seal carrier 1 7 is disposed in each of the two passage openings I and II, and, as shown in Figure 1 this has a Z cross-section. Each seal carrier 1 7 is secured hermetically to the flap frame 1 and to the tubular member 14. A gasket 1 8 is located in each seal carrier 17, and the flaps 4, 5 with projecting sealing strips 19, 20 bear hermetically on the respective gaskets.

In Figure 2 at the top there is an arrangement with a double seal comprising an outer gasket 1 8 and an inner gasket 18' co-operating with a second projecting sealing strip 19'. Between the two gaskets 18 and 18' there is an intermediate space 21 which is provided with an exhaust duct 22 by which the tightness of the sealing can be continually tested. At the bottom in Figure 2 there is an illustration of an alternative arrangement having only a single gasket 18. The shaft packing 1 6 may also be furnished with an exhaust duct for testing for leakage. A passage 23 for this purpose is shown in the shaft 2. The passage 23 is connected to the intermediate space between the two gaskets 16. Drill-holes for testing for leakage may also be provided in the seal carriers 1 7 and have exhaust ducts connected to them.

As mentioned hereinbefore, the tubular member 14 around the shaft 2 may consist of a tube provided with lateral cutouts through which the lever arms 6, 12 pass and are joined to the shaft 2. In relation to the technique of manufacture, however, an embodiment is especially advantageous wherein the tubular member 14 consists of semi-cylindrical shells, which in the form of embodiment shown in Figure 1 are open towards the observer in the region of the lever arm 6 and are open away from the observer in the region of the lever arm 12. These shell sections can be joined to one another via the seal carrier 15, for example they may be welded by an annular bead.

No separate seal need be provided to pass the shaft 2 through its bearings 3, provided the valve actuator is disposed in a space into which the flap 4 swivels in the opening sense.

Claims (10)

Claims

1. A flap valve comprising at least one flap, a shaft on which the or each flap is carried, a flap frame against which the flap is sealed around its periphery when the valve is closed, the or each flap being mounted on the shaft by at least one lever arm fixed to the shaft and extending outwardly of the axis of rotation thereof, the valve also comprising a tubular member surrounding the shaft and connected hermetically at each end of the tubular member to the flap frame and having lateral opening in the region of the or each lever arm and through which the lever arm extends, annular sealing means positioned between the shaft and the tubular member adjacent the or each lateral opening, a first peripheral sealing face on the or each flap, a second sealing face on said flap frame and on the tubular member a resilient sealing gasket on one of said sealing faces and sealingly engaged by the other of said sealing faces around its whole periphery when the valve is closed.

2. A flap valve as claimed in Claim 1 having a pair of flaps mounted on the shaft at diametrically opposite positions thereon by a pair of lever arms on each flap, each lever arm extending through a respective lateral opening in the tubular member, one lever arm of each pair extending in opposite directions through respective oppositely-directed lateral openings between which there is one said annular sealing means to prevent communication between said oppositely-directed lateral openings.

3. A flap valve as claimed in Claim 1 or 2 in which the or each flap is arranged to swivel on the lever arm or respective lever arm.

4. A flap valve as claimed in any preceding claim in which the or each lever arm is mounted on a locking ring secured to the shaft.

5. A flap valve as claimed in any preceding claim in which the or each annular sealing means comprises an annular seal carrier joined hermetically at its outer periphegy to the inside of the tubular member and at least one annular sealing gasket positioned between the annular carrier and the shaft.

6. A flap valve as claimed in Claim 5 in which the tubular member comprises part-cylindrical cooperating shells which are joined together by or within the or each annular seal carrier.

7. A flap valve as claimed in any preceding claim in which the resilient sealing gasket is mounted on the flap frame and comprises double gaskets spaced apart on the flap frame and defining a space therebetween.

8. A flap valve as claimed in any preceding claim in which the annular sealing means between the shaft and the tubular member comprises a pair of gaskets spaced apart axially of the tubular member and acting in opposite directions and defining a space therebetween.

9. A flap valve as claimed in Claim 7 or 8 in which the space defined between the respective gaskets communicates with a duct through which leakage past the gaskets into the respective space is detectable.

10. A flap valve contructed and arranged substantially as described herein and shown in the accompanying drawings.