GB2234499A

GB2234499A - Handling viscous products

Info

Publication number: GB2234499A
Application number: GB9016996A
Authority: GB
Inventors: George Leslie Potter
Original assignee: FLEXIFILLING MACHINES Ltd
Current assignee: FLEXIFILLING MACHINES Ltd
Priority date: 1989-08-02
Filing date: 1990-08-02
Publication date: 1991-02-06
Anticipated expiration: 2010-08-02
Also published as: GB9016996D0; GB8917672D0; GB2234499B

Abstract

In order to reduce the tendency to adhesion of a viscous flowable product in a container or passage to an associated surface 9, that surface is defined by a porous body 8 and a fluid is supplied to the surface 9 through the body to form a film between the body and product when they are to be detached from one another. The surface 9 may form part of a valve closure member 5 of a filling nozzle 1, or form the inside surface of a container lid. <IMAGE>

Description

HANDLING VISCOUS PRODUCTS This invention relates to the handling of viscous, creamy and semi-liquid products, particularly to the filling of containers with viscous or adhesive products. It is common when filling containers to use a nozzle having a dispensing orifice which provides a seating for a valve head located within the nozzle.

When the filling material is a creamy or semi-liquid product a tail of the product may be left on the valve head. This can cause problems in situations where a clean break or discontinuity in flow is required.

This has been a long standing problem in the field of filling containers and a number of solutions have been attempted, none of which have proved particularly satisfactory. Known solutions include: sucking the tail off with a vacuum source; directing a blast of air to blow the tail off; sucking air back through the nozzle; and mechanically wiping the tail off the nozzle.

Vacuum sucking off causes problems when the material is very viscous or adhesive, while blowing the tail off often results in the material of the tail being blown over the container and preventing the container being adequately sealed. If air is sucked back through the nozzle it often results in a plug of material being drawn back through the nozzle yet still leaving a tail hanging from an inside surface of the nozzle.

Mechanically wiping the tail off complicates the mechanism and can be a source of contamination.

It is also known (for example from British Patent Specification No. 2 179 928A) to clean out the bore of a dispensing valve for viscous food products by blowing an inert gas through the bore of the valve; however this does nothing to help to detach the product where it is highly viscous.

Not only in dispensing valves but also in containers for viscous products there can be a problem in detaching the product from a part of the container, in particular from its lid or stopper when the container is to be opened.

According to the invention we propose to reduce the tendency to adhesion of a viscous flowable product in a container or passage to a surface associated with that container or passage to a surface associated with that container or passage comprising the provision of a porous body to define that surface and the step of supplying a fluid to that surface through the body to form a film between the body and the product when the product and surface are to be detached from one another.

Flow of the fluid through the porous body helps to detach the material from the body, resulting in a self cleaning action, by reducing the effect of surface tension or natural adhesion of the product to the contact surface.

The invention is of particular value in dispensing mechanisms for filling containers with viscous or adhesive products.

Where the invention is applied to a dispensing nozzle a nozzle is provided having a valve head on a stem within the nozzle, the valve head comprising a porous body and a fluid supply passage being located within the stem and fluid being fed through the porous body towards a contact surface of the body which is in contact with filling material at least while the valve is in an open position.

The invention enables a mechanical filling system with a controlled release of adhesion to be provided.

The fluid may be either a liquid or a gas but it is preferably a liquid of low volatility so that the liquid remains as a film on the contact surface.

Advantageously the liquid is non-contaminating towards the product material. Other preferred properties of the fluid are that it is non-volatile and inert relative to the product material both in a container and when it is used.

Preferably the fluid should not form any deposits within the porous element.

The fluid may be aqueous or an oil or alcohol.

Alternatively inert gases may be utilised.

An embodiment of the invention will now be further described by way of example only with reference to the accompanying drawings in which: Figure 1 shows a nozzle valve assembly having a means for reducing adhesion in accordance with the present invention with a valve in an open position, and Figure 2 shows the nozzle with the valve closed.

A nozzle 1 for filling containers 2 with a viscous product 3 is provided with a means for reducing adhesion of the material 3 to a valve 4 controlling flow of the material into the container. The means comprises a valve head 5 on a stem 6. The valve head 5 comprises a housing 7 and a porous body 8 having a contact surface 9 which is in contact with the material which flows round the valve head 5 when the valve is open as shown in Figure 1. A passage 10 extends through the stem to the porous body and is adapted to feed fluid 13 to the porous boy. The supply of fluid to the body is controllable. Preferably fluid is only fed to the porous body for a short period after the valve is closed, but may continue throughout a filling cycle.

It will be appreciated that in the construction as shown, as the main part of the valve head 5 and stem 6 are fully immersed in the product within the nozzle even when the valve is closed, it is only the exposed lower surface of the head that has the adhesion problem being exposed to atmosphere in the closed position of the valve and as this surface is substantially wholly formed by the porous body the problem is overcome.

Fluid may be delivered to the contact surface by a static head or by a variable pressure, and may be continuous or intermittent. Fluid being fed to the porous element reduces the effect of surface tension and/or adhesive properties of the material at the contact surface. Consequently a tail 11 of material that may initially form on the contact surface of the element becomes readily detachable when fluid is supplied and drops off the nozzle allowing a surface film 12 on the contact to being replaced.

The invention facilitates achieving a clean cut-off which can be important especially when the material has adhesive properties and/or is very viscous.

Suitable fluids include inert gases, mineral or vegetable oils, alcohols and water. Solutions may be used but care must be taken in their selection to avoid problems with deposition in the porous element and so pure liquids are preferred.

Although the invention is illustrated as being applied to a valve member in a nozzle-type dispensing valve assembly, it could be applied to other forms of passage, and even to the surfaces of containers, e.g.

the inside surface of a lid or other closure forming part of the wall of the container.

Claims

1. A method of reducing the tendency to adhesion of a viscous flowable products in a container or passage to a surface associated with that container or passage comprising the provision of a porous body to define that surface and the step of supplying a fluid to that surface through the body to form a film between the body and the product when the product and surface are to detached from one another.

2. A method according to claim 1 in which the surface is that of a movable valve member past which the product moves, and in which the fluid is supplied when the valve member is moved to its closed position to cut off the flow of product.

3. A method according to claim 1 or claim 2 in which the fluid is a liquid.

4. A method according to claim 2 as applied to a valve member of an intermittently operating filling machine for filling a series of containers.

5. Means for carrying out the method of claim 1 comprising a container or passage incorporating as part of it a porous body having a surface which is at times in contact with a viscous flowable product within the container or passage and at other times is to be detached from that product, and controllable means for supplying a fluid to that surface through the body itself to form a film between the body and the product when that detachment is required.

6. Means according to claim 5 in which the passage is a valve assembly controlling the flow of the product and the body is formed in a movable valve member forming part of that valve assembly within a surrounding nozzle, the fluid supply means being controlled to supply fluid to the surface through the body when the valve member is moved to the closed position.

7. A valve assembly incorporating the means according to claim 6, in which the valve member of the valve assembly is a poppet valve having a stem and a head past which the product flows to atmosphere, and the body is placed such that the surface in question forms that part of the head of the valve member, which is exposed to atmosphere when the valve is closed.

8. A valve assembly according to claim 7 in which the fluid is passed to the body down the stem of the valve member.

9. A filling machine for dispensing a viscous flowable product intermittently and having a dispensing valve assembly in accordance with claim 7 or claim 8.

10. A method of reducing the tendency to adhesion of a viscous flowable product in a container or passage according to claim 1, substantially as described with reference to the accompanying drawings.

11. Means for carrying out the method of claim 9 substantially as described with reference to the accompanying drawings.

12. A filling machine for dispensing a viscous flowable product intermittently through a valve assembly, the valve assembly being substantially as described with reference to the accompanying drawings.