Closure device for stores of flowable material and store of flowable material having said closure device

Abstract

 A closure device 10 for a store of flowable material is made of elastomeric material. It is also preferably solid with no enclosed cavities or confined spaces.

Description

[0001] This invention relates to a closure device for a store of flowable material, such as a silo or an intermediate bulk container, and to a store equipped with such a closure device.

[0002] It is well known, e.g. from GB-A-2348636, to provide a closure device in the form of a cone valve to close a discharge opening of a store (such as a hopper) of flowable material, e.g. powder or other particulate material. These known valves are hollow and of plastic's material or flexible steel. The known valves will provide an effective seal against passage of cohesive powders but do not work without a separate seal for super fine powders.

[0003] According to a first aspect of the present invention, there is provided a closure device for a store of flowable material, the closure device being made of elastomeric material.

[0004] The closure device, being made of elastomeric material, will provide an effective seal against passage not only of cohesive powders but also of super fine powders.

[0005] The closure device may be solid and have no enclosed cavities or confined spaces.

[0006] Preferably, the closure device has a conical upper portion and an endless rim at the lower end of the conical portion for sealing against a wall of the store. Advantageously, the thickness of the rim reduces as it extends away from the lower end of the conical portion. This renders the free edge of the rim more flexible and improves its sealing abilities.

[0007] The closure device may further comprise an endless wall within the rim and projecting from the lower surface of the conical upper portion to define a recess for receiving part of a closure operating member. In this case, the thickness of the endless wall may reduce as it extends away from the conical portion. This renders the free edge of the rim more flexible allowing it to make a further seal with the wall of the store.

[0008] According to a second aspect of the present invention, there is provided a store of flowable material having a closure device according to the first aspect of the invention and a discharge opening closable by the closure device.

[0009] The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a sectional view of one embodiment of a closure device according to the present invention, and

Figure 2 is a section taken through the closure device shown in Figure 1 and through part of a store to illustrate the manner in which the closure device seals to the wall of the store.

[0010] Referring to the drawings, the closure device 10 shown therein is intended to close the discharge opening of a store 20 (see Figure 2) of flowable particulate material, such as a silo or an intermediate bulk container containing powder or granular material, and is typically operated by a closure operating member movable upwardly by an actuator in a manner such as that described in GB-A-2348636.

[0011] The closure device 10 has a conical upper portion 11, an endless rim (or outer skirt) 12 at the lower end of the conical portion 11 for sealing against a wall of the store 20 and an endless wall (or inner skirt) 13 within the rim 12 and projecting from the lower surface of the conical upper portion 11 to define a recess 14 for receiving part of a closure operating member in the form of a probe (not shown but see GB-A-2348636).

[0012] The closure device 10 is made of elastomeric material, typically rubber or polyethylene.

[0013] The closure device 10 may be solid with no enclosed cavities or confined spaces. It can thus be totally sanitary. In this case it can be injection moulded entirely of elastomeric material or can contain a steel insert 15 as shown.

[0014] As shown in Figure 2, both the rim 12 and the lower end of the wall 13 seal against the wall of the store 20.

[0015] The thickness of the rim 12 reduces as it extends away from the lower end of the conical portion 11 and the thickness of the endless wall 13 gradually reduces in tapered manner as it extends away from the conical portion 11. Typically the thickness of the rim 12 and endless wall 13 both reduce down to about 3 mm at their free ends. This increases the flexibility of the rim 12 and the wall 13 and improves their sealing abilities to the wall of the store 20 and the probe, respectively. By using elastomeric material for the closure device, it has been found that the closure device will provide an effective seal not only against passage of cohesive powders but also an effective seal against passage of super fine powders. This means that no separate gasket or seal has to be provided on the valve or the store and this renders the apparatus totally hygienic. Also, it is maintenance free and assembly/removal is made simple.

[0016] The double seal, namely that provided between the endless rim 12 and the wall of the store 20 and that provided between the endless wall 13 and the wall of the store 20, ensures stability of the closure device with no tipping or leakage. The upper seal between the rim 12 and the wall of the store 20 prevents or substantially prevents any product pressure on the lower seal between the wall 13 and the wall of the store 20 so that the lower seal only has to seal against dust and/or a small amount of product between the two seals. By contrast, a single soft seal at the outlet results in the product pressure forcing product through the outlet particularly as fine powders can easily become fluidised and act like a low viscosity liquid. Furthermore, as the wall 13 is flexible, it will establish a good seal with a tapered closure operating member with the result that the only product exposed to atmosphere will be the thin ring of product dust at the bottom edge of the endless wall 13.

[0017] In use, the actuator will move the probe upwardly to open the closure device 10 and can then be operated to pulse the closure device upwards and downwards in order to break up powder above the upper surface of the conical portion 11 as more particularly described, for example, in GB-A-2348636.

Claims

1. A closure device for a store of flowable material, the closure device (10) being made of elastomeric material.

2. A closure device as claimed in claim 1, which is solid and has no enclosed cavities or confined spaces.

3. A closure device as claimed in claim 1 or claim 2, which has a conical upper portion (11) and an endless rim (12) at the lower end of the conical portion for sealing against a wall of the store.

4. A closure device as claimed in claim 3, wherein the thickness of the rim (12) reduces as it extends away from the lower end of the conical portion (11).

5. A closure device as claimed in claim 3 or claim 4, further comprising an endless (13) wall within the rim (12) and projecting from the lower surface of the conical upper portion (11) to define a recess (14) for receiving part of a closure operating member.

6. A closure device as claimed in claim 5, wherein the thickness of the endless wall (13) reduces as it extends away from the conical portion (11).

7. A store of flowable material having a closure device (10) as claimed in any one of the preceding claims and a discharge opening closable by the closure device.

8. A store as claimed in claim 7, in the form of a silo or intermediate bulk container (20).

Drawing