GB2295384A

GB2295384A - Dispensing valve

Info

Publication number: GB2295384A
Application number: GB9423666A
Authority: GB
Inventors: Andrew Bryan Birchall; William Taylor
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 1994-11-23
Filing date: 1994-11-23
Publication date: 1996-05-29
Also published as: GB9423666D0

Abstract

A dispensing valve (10) enables a fluid such as a powder to be dispensed from one container (12) to another such as a flask (14). The valve assembly includes a duct (16) tapering to a port at one end, and a variable-length enclosure (34) supported within the duct (16), the enclosure (34) defining at one end a valve door (40) for the port, and including means (48, 50, 54) to clamp a lid (26) of the flask (14) to the outside of the door (40). The door (40) has a seal (42) to seal to both the port and the lid (26), and the flask (14) is also sealed to the outside face of the port. The valve enables a powder to be transferred between the containers (12, 14) without contacting any external surfaces of the flask (14), the lid (26) or the valve (16, 40). <IMAGE>

Description

Dispensinq Valve This invention relates to a valve assembly for dispensing a fluid medium, such as a powder, from one container to another.

A variety of valve designs are known for controlling the flow of a fluid, such as a powder, between two containers for example from a storage container into a transport container or vice versa. In some circumstances it would be desirable to ensure that the containers effectively isolate their contents from the surroundings at all stages both before, during, and after the flow of the fluid between them.

According to the present invention there is provided a valve assembly for dispensing a fluid medium from a first container into a second container, wherein the second container defines an aperture for flow of the medium, the aperture being provided with a lid pushfitting within the aperture, and the valve assembly comprising a duct communicating at one end with the first container, and at the other end defining a port of smaller cross-sectional area than the duct which port is of such dimensions that the lid can just fit through it, the port being provided with a valve door with a peripheral seal to the port, an actuator supported within the duct for moving the valve door in or out of sealing engagement with the port, and means for clamping the lid to the door.

Preferably the peripheral seal on the door is such as to seal to the lid as well as the port, when the lid is clamped to the door. Preferably a seal is also provided to seal between abutting edges of the port- and aperture-defining means; this seal may form part of the second container, and seal also to the lid.

Such a valve assembly provides the benefits of a double-lid transfer system, as the contents of the containers are at all times isolated from the surroundings, and do not contact external surfaces of the lid or door or of either container. It therefore provides advantages where the powder may be toxic or hazardous.

The valve assembly is particularly suited where the fluid medium is a powder. In this case the duct is desirably arranged to extend generally vertically, and to taper gradually to the port, so there are no horizontal surfaces on which powder would tend to build up. The actuator is preferably a linear actuator, and is desirably enclosed within a variable-length enclosure one end of which is supported, the other end of which defines the valve door; the walls of this enclosure may be defined by an elastic sleeve, a flexible bellows, or by telescopic tubes for example.

The linear actuator and the clamping means are preferably actuated hydraulically or pneumatically, particularly where the medium is powder, as any risk arising from sparks from electric motors is thereby avoided. The preferred embodiment utilises pneumatic actuation. The clamping means might be a vacuum clamp if the lid is smooth, or more preferably is a mechanical clamp comprising a plurality of latching members arranged to engage with the lid. In the preferred embodiment the lid defines an internal lip, and the clamping means incorporates latching members rotatable to engage or disengage the lip; it also incorporates a rotary actuator to rotate the latching members.

The lid may be of a resilient material such as polyethene, and may define a peripheral groove or ridge to engage with a corresponding peripheral ridge or groove within the aperture to reduce the risk of the lid falling out of the aperture if the second container were to be accidentally dropped. After the second container with its lid has been removed from the valve assembly, a mechanical band or other clamp may be fitted to it to hold the lid in place more securely.

The invention will now be further and more particularly described, by way of example only, and with reference to the accompanying drawings in which: Figure 1 shows a longitudinal sectional view of a valve assembly connecting two containers (on the line I-I of Figure 3); Figure 2 shows a peripheral seal of Figure 1 to a larger scale; Figure 3 shows a sectional view on the line III-III of Figure 1; and Figure 4 shows a sectional view on the line IV-IV of Figure 1.

Referring to Figure 1, a powder dispensing valve assembly 10 enables a powder stored in a storage container 12 to be dispensed into a portable flask 14, for example a 200 litre flask; only a fragmentary part of the container 12 is shown, and only the conical neck of the flask 14. The valve assembly 10 incorporates an upright generally cylindrical duct 16 with a flange 17 at the top for connection to the container 12, a flanged joint 18 about half-way along it to facilitate dismantling and cleaning, and a glass viewing window 19 at one side of the duct 16. The lower part of the duct 16 tapers conically to a circular port, whose walls are also slightly inclined, so the narrowest part of the port is at its lowest point. The duct 16 defines a flat annular surface around the open end of the port, surrounded by a short tube 20 to locate the top of the flask 14.A flask-support ring 21 is attached to the outside of the tube 20 and can be rotated by means of handles 22; the tube 20 defines two vertical notches 23, and the ring 21 defines two L-shaped slots which in one position of the ring 21 align with the notches 23.

The flask 14 is shown connected to the valve assembly 10, but with the valve closed. The neck of the flask 14 defines a cylindrical aperture with a peripheral ridge 24 within it. A generally conical lid 26 of polyethene locates in the neck. The upper part of the lid 26 is annular, defining an external peripheral groove in which the ridge 24 engages, and defining an inwardly projecting lip 28. This upper part is thick-walled, and is joined to the lower thick-walled conical part by a thin-walled conical part 29. The part of the lid 26 of largest diameter is just small enough to fit through the port into the duct 16. The top end of the flask 14 around the aperture is thick-walled, and two rods 30 project from it radially as handles. The rods 30 locate in the notches 23 and in the slots in the ring 21, such that when the ring 21 is turned the flask 14 is securely supported.A peripheral seal 32 is provided around the top end of the aperture which is shown to a larger scale in Figure 2 (in the absence of the lid 26 and the duct 16); in the position shown in Figure 1 the seal 32 seals to both the lid 26 and to the flat face around the port of the duct 16.

Within the duct 16 is a sealed valve enclosure 34 with a generally cylindrical body portion and a conical top. The enclosure 34 comprises upper and lower parts 35 and 36 connected by a flexible bellows 37, so the length of the enclosure 34 can vary. The upper part 35 of the enclosure 34 is fixed concentrically within the cylindrical part of the duct 16 by three radiallyextending pipes 38 (see Figure 3). The lower part 36 of the enclosure 34 defines a door 40 for the port with a seal 42 around its periphery which in the position shown seals to both the wall of the port, and to the top of the lid 26. The two parts 35 and 36 of the enclosure 34 are kept in alignment by three guide rods 44 (see Figure 3).

The upper part 35 of the enclosure 34 contains a pneumatic linear actuator 46 (shown in elevation), which moves a piston rod 47 to whose lower end the lower part 36 of the enclosure 34 is fixed. The lower part 36 encloses a pneumatic rotary actuator 48 (shown in elevation) whose drive shaft 50 projects below the door 40; below the door 40 it is keyed to a toothed cylinder 52 whose teeth engage toothed portions of the peripheries of four, approximately semicircular, clamping latches 54 (see Figure 4; only one latch 54 is shown in Figure 1) which are rotatably mounted on the underside of the door 40. In the position as shown the latches 54 engage the underside of the lip 28, so the lid 26 of the flask 14 is clamped onto the door 40. A circular cover plate 56 is attached to the lower end of the cylinder 52.

Pneumatic pipes 60 cornmunicate with the linear actuator 46, and similar pipes 62 communicate with the rotary actuator 48. The pipes 62 incorporate polyurethane spring coils 64 to accommodate changes in length of the enclosure 34, and quick-release couplings 66. The pipes 60 and 62 extend out from the enclosure 34 to a control panel (not shown) via the radial support pipes 38, as is shown for one of the pipes 62 in Figure 1.

In operation a flask 14 is lifted by an operator so as to mate with the tube 20 at the lower end of the duct 16, ensuring the handles 30 of the flask 14 locate in the notches 23 and in the slots in the flask-support ring 21.

The operator then rotates the ring 21 by means of the handles 22. The rotary ctuator 48 is then actuated to rotate the latches 54 to clamp the lid 26 to the underside of the door 40. The flask 14 and the valve assembly 10 are then as shown in Figure 1. The linear actuator 46 is then actuated to shorten the enclosure 34 and so to raise the door 40, and with it the lid 26.

Powder then flows from the container 12 through the annular space between the enclosure 34 and the duct 16, through the port, and so into the flask 14.

When the powder transfer has been completed, the linear actuator 46 is actuated to lengthen the enclosure 34, so the door 40 again seals to the port, and the lid 26 again seals the mouth of the flask 14. The rotary actuator 48 is operated to release the latches 54 from the lip 28. The flask-support ring 21 can then be rotated to release the handles 30, and the flask 14, sealed by its lid 26, is then lowered and removed. It will be appreciated that throughout these operations the powder is always enclosed within the container 12, the duct 16, and the flask 14, and that the powder does not contact any external surfaces of the duct 16, the door 40, the flask 14 or the lid 26.

It will be appreciated that a valve assembly may differ from that described above while remaining within the scope of the invention. For example a valve assembly 10 may be installed the other way up, so a powder can be transferred out of a flask 14 and into a hopper or another container 12. The valve assembly may differ in shape and size from that shown, though it is desirable that the cross-sectional area of the annular powder flow channel surrounding the valve enclosure 34 should be substantially the same as that of the port, so as to reduce the risk of powder blockages occurring in the valve assembly. The bellows 37 might be replaced by an elastic sleeve, and this would provide a smoother-walled powder flow path. The linear and rotary actuators might differ from those described, and in particular the rotary actuator might be fixed within the stationary part of the valve enclosure, along with the linear actuator; this would reduce the mass which the linear actuator would have to move.

Claims

1. A valve assembly for dispensing a fluid medium from a first container into a second container, wherein the second container defines an aperture for flow of the medium, the aperture being provided with a lid pushfitting within the aperture, and the valve assembly comprising a duct communicating at one end with the first container, and at the other end defining a port of smaller cross-sectional area than the duct which port is of such dimensions that the lid can just fit through it, the port being provided with a valve door with a peripheral seal to the port, an actuator supported within the duct for moving the valve door in or out of sealing engagement with the port, and means for clamping the lid to the door.

2. A valve assembly as claimed in Claim 1 wherein the peripheral seal on the door is such as to seal to the lid as well as to the port, when the lid is clamped to the door.

3. A valve assembly as claimed in Claim 1 or Claim 2 wherein a seal is provided to seal between abutting edges of the port- and aperture-defining means.

4. A valve assembly as claimed in any one of the preceding claims wherein the actuator is a linear actuator and is enclosed within a variable-length enclosure one end of which is supported within the duct and the other end of which defines the valve door.

5. A valve assembly as claimed in any one of the preceding claims wherein the lid defines an internal lip, and the clamping means incorporates latching members rotatable to engage or disengage the lip, and a rotary actuator to rotate the latching members.

6. A valve assembly substantially as hereinbefore described with reference to and as shown in the accompanying drawings.