GB2076679A

GB2076679A - Liquid admixing device

Info

Publication number: GB2076679A
Application number: GB8115622A
Authority: GB
Original assignee: Total Foerstner & Co GmbH
Current assignee: Total Foerstner & Co GmbH
Priority date: 1980-05-24
Filing date: 1981-05-21
Publication date: 1981-12-09
Also published as: SE8103048L; FR2482870B3; GB2076679B; FR2482870A1; ATA208581A; NL8102314A; AT384305B; DE3019987A1; CH652614A5; SE448610B; DE3019987C2

Abstract

A liquid admixing device has an operating head (10) for mounting on a container (14) to contain liquid to be admixed and a pipe (24) for a carrier liquid under pressure, the pipe having an upstream tapping (20) into a bore (23) which leads to the container (14), to allow carrier liquid to be transmitted to the storage container. The pipe (24) also has a junction downstream leading from the container to allow the liquid to be admixed with the carrier liquid and thence expelled. An elastomeric membrane (15) is located in the container to separate the carrier liquid from the liquid to be admixed, pressure of the carrier liquid being transmitted via the membrane to force the liquid to be admixed into the pipe (24) via the junction (21). A shut-off valve (25), operable by the liquid pressure differences is provided in the pipe (24) to shut off supply of the carrier liquid once the liquid to be admixed has been exhausted or is running out. <IMAGE>

Description

SPECIFICATION Liquid admixing device According to the present invention, there is provided a liquid admixing device comprising an operating head for mounting on a storage container for containing a liquid to be admixied with a carrier liquid, the operating head including in it a pipe for receiving under pressure and expelling the carrier liquid, said pipe having an upstream tapping into a bore intended to lead to the storage container, to allow carrier liquid from said pipe to be transmitted under pressure to said storage container, and a downstream junction with a bore intended to lead from the storage container, to allow the liquid to be admixed to be fed to said pipe to be admixed with said carrier liquid, and there being an elastomeric membrane for positioning in the container to separate the carrier liquid in the container from the liquid in the container to be admixed.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing, in which the single figure is a diagrammatic sectional side view of a liquid admixing device.

The drawing shows a liquid admixing device whose main operating components are arranged in a body or head 10, which is advantageously made of a synthetic plastics material. On one of its surfaces, which is a bottom surface 11 in the normal operating position of the device, this head 10 is provided with an annular flange 12, which serves as a co-acting flange with a flange 13 provided on an upper open rim of a storage container 14.

When the device is assembled, ready for operation, a rim of an elastomeric (possibly rubber) membrane 15 is tightly clamped all around its periphery between the flange surfaces of the container 14 and the head 10. The space 16 inside the membrane 15 is intended for receiving a liquid agent, for example, a foaming agent, which is to be admixed with a carrier liquid passing through the head 10. The inside wall of the container 14 and the outside wall of the membrane 15 define a space 17 which is provided in order to accommodate a liquid displacement medium.

The carrier liquid, which is to be admixed with the admixing agent, is caused to flow under pressure through a pipe 24 in the head 10. This pipe extends from an inlet opening 18 to an outlet opening 19 in the head 10 and has an upstream tapping at 20 and a downstream junction at 21.

Between these two points 20 and 21, a pressure drop is established as a consequence of the flow of the carrier liquid, and this pressure drop is further strengthened by the fact that the region of the junction 21 is formed as a venturi tube 22, i.e.

is constricted, this leading to an increased throughflow velocity and a fall in pressure. This pressure drop between the points 20 and 21 forms the pressure head, by means of which the admixing agent is forced at 21 into the carrier liquid. A bore 23 connects the tapping 20 with the space 17, so that the pressure of liquid at the tapping 20 is transmitted via the bore 23 to the space 17. Between the points 20 and 21, the pipe 24 for the carrier liquid contains a valve 25, which operates as an independent shut-off valve as will be described.

The head 10 carries on the surface 11 which is facing the container 14 a perforated plate 26, which is fixed around its periphery to the surface 11 and is spaced radially inwards from the surface 11 thereby to enclose a space 27. The surface 11 has two openings within its area enclosed by the perforated plate 26, namely, an opening 28 of a bore 29, which provides a connection with a filling opening 30 for the container 14, and an outlet 31 for the admixture medium from the container 14, from which outlet a bore 32 extends to the junction 21. A non-return valve 33 and a proportioning valve 34 are arranged in the bore 32. All these bores and valves are arranged in the head 10. The head 10 also contains an automatic air-venting valve 35 in a venting duct 43, which connects the space 17 with the ambient air.

The valve 25 consists of a valve member, which is moved, for closing the valve, onto a valve seat 36 in the intended direction of the flow of the carrier liquid, so that the valve member closes under the pressure causing the flow, provided that additional forces are not effective on the valve member. An annular packing 41 on the valve 25 provides the seal with the valve seat 36. However, in order to actuate the valve 25, a rigid connection by means of a valve rod 37 to a control piston 38 is provided. This control piston is likewise arranged in the head 10 and its bottom end surface 39 faces the space 27, so that the pressure in the space 27 can act on the piston 38.

The piston 38 is in sealing contact around its circumference with a cylindrical wall in the housing 10. On the surface 40 opposite to the surface 39, the piston 38 is hydraulically connected with the pipe 24 beneath the valve 25.

The surface 39 is larger than that surface which is enclosed by the annular packing 41 on the valve 25, when the valve is closed onto the valve seat 36, so that, with equal pressures in the space 27 and in the upstream portion of the pipe 24 and because of the difference in size of the effective valve/piston surfaces, the valve 25 will be lifted and opened.

So that the displacement liquid branched off from the carrier liquid through the tapping 20 is able to leave the space 17, a draining cock 42 is provided in the bottom part of the container 14.

Operation of the device will now be described assuming that it is filled and ready for use. The space 16 is then full of admixture liquid, e.g. a foaming agent (or, for example, a disinfecting or cleaning liquid), and the discharge cock 42 is closed. Let it be assumed that the carrier liquid is water, with which the medium or agent is to be admixed.

The device is set in operation by the inlet 18 being connected to a water source at an appropriate water pressure. By way of the upstream portion of the pipe 24, the water passes under pressure to the valve 25 and by way of the bore 23 into the space 17. The pressure in the space 1 7 is transmitted by way of the liquid filled spaces 1 6 and 27 to the surface 39 of the control piston 38. Even if the valve 25 were closed, it will now become opened, because there is the same pressure on its two effective surfaces, which are determined by the surface 39 and the packing 41, so that the direction of the movement of the valve 25 is determined by the larger surface 39. As a consequence, by means of the rod 37, the valve member 25 is lifted, as a result of which the path from the inlet 18 to the outlet 19 is opened.The flowing liquid produces the pressure head and the foaming agent, for example, is displaced, by the water entering the space 17 at 20, through the perforated plate 26 and the space 27 into the bore 32. At 21, it enters the flow of water and consequently is here admixed therewith. During this operation, substantially equal pressures obtain on the two end surfaces 39, 40 of the piston 38.

If the admixture medium has been substantially consumed, the membrane 15 will be caused to bear against the perforated plate 26. Any further displacement is thus made impossible and the pressure in the chamber 27 then decreases to a pressure reduced by the pressure head. This lower pressure is also the same at the piston surface 39, whereas the full water pressure applies on its opposite surface 40. The control piston is thus moved towards the space 27 and consequently, carried with it, by means of the rod 37, the valve member of the shut-off valve 25, until the latter is tightly closed on its seat 36. Thus, the device is in this way automatically switched off once the admixture medium has been exhausted or almost exhausted, the valve 25 preventing any incorrect proportioning of the admixed liquid.

In order to make the device once again ready for operation, it has first of all to be filled. For this purpose, the discharge cock 42 is opened and then the admixture medium is admitted into the space 16 through the filling opening 30, which is of course closed during operation. The space 16 can be filled to such an extent as is permitted by the container 14, that is, until the membrane 15 is caused to bear against the inside wall of the container 14. Any air which is between the container 14 and membrane 15 is able to escape through the automatic air-venting valve 35, so that a uniform, pulsation-free operation is guaranteed.

The non-return valve 33 prevents water from penetrating from the pipe 24 into the admixing medium.

Instead of using a control piston 38, the valve 25, 36, 41 can also be controlled by a suitably arranged and designed membrane or diaphragm actuable by the pressure difference between that in the pipe 24 and that in the space 16.

As an example, a liquid additive up to 5 percent can be admixed with a stream of water using the present device. The flow of water is advantageously between 5 litres per minute and 30 litres per minute.

The proportioning valve 34 permits a variable adjustment of the admixiture ratio, which is independent of the strength of the throughflow.

It is possible for containers which are of quite different size to be connected to the flanged rim 12 of the head 1 0. All that is necessary is for the containers to have complementary flanges.

Containers which are preferred are those with volumes between 5 and 15 litres.

Claims

1. A liquid admixing device comprising an operating head for mounting on a storage container for containing a liquid to be admixed with a carrier liquid, the operating head including in it a pipe for receiving under pressure and expelling the carrier liquid, said pipe having an upstream tapping into a bore intended to lead to the storage container, to allow carrier liquid from said pipe to be transmitted under pressure to said storage container, and a downstream junction with a bore intended to lead from the storage container, to allow the liquid to be admixed to be fed to said pipe to be admixed with said carrier liquid, and there being an elastomeric membrane for positioning in the container to separate the carrier liquid in the container from the liquid in the container to be admixed.

2. A device as claimed in claim 1, wherein said operating head carries a perforated plate on a face of the operating head that is intended to face the storage container, said perforated plate defining a space between itself and said face.

3. A device as claimed in claim 1 or 2, wherein said pipe has a valve therein, the position of which being dependent upon the difference between the pressure in the pipe and the pressure in the storage container on the side of said elastomeric membrane that is intended to contain said liquid to be admixed.

4. A device as claimed in claim 3, wherein said valve comprises a rigid connection with a piston which is arranged to be in sealing and sliding engagement with an internal wall in said head, one piston surface being able to be acted upon by the pressure of said carrier liquid in said pipe and an opposite surface of the piston being able to be acted upon by pressure, in use of the device, in said storage container on the side of said membrane that is to contain the liquid to be admixed.

5. A device as claimed in claim 4, wherein said valve has an effective valve surface enclosed by a seating that is smaller than the surface of said opposite side of said piston so that, when the .valve is closed, the pressure to operate the valve is obtained from the pressure upstream in said pipe and the pressure acting on said opposite side of said piston.

6. A device as claimed in claim 1, 2 or 3, wherein said valve is operated by a membrane or diaphragm which relies on the pressure difference between the pressure in an upstream part of said pipe and that in said container on the side of said elastomeric membrane that is intended to contain said liquid to be admixed.

7. A device as claimed in any one of the preceding claims, wherein said operating head includes a venturi nozzle in the region of said dowstream junction.

8. A device as claimed in any one of the preceding claims, wherein said operating head includes a bore which is intended to lead into said container so that the container may be filled with said liquid to be admixed.

9. A device as claimed in any one of the preceding claims, wherein said bore intended to lead from said storage container includes a nonreturn valve to prevent the carrier liquid from flowing into the storage container.

10. A device as claimed in any one of the preceding claims, wherein said operating head includes an air-venting valve to allow air to escape from the container on the side of said elastomeric membrane that is to contain the carrier liquid.

11. A device as claimed in any one of the preceding claims, wherein said bore intended to lead from said storage container includes a valve to regulate the proportion of liquid from the container to be admixed with the carrier liquid.

12. A device as claimed in any one of the preceding claims, wherein said operating head is provided with a peripheral flange and wherein a said storage container is provided and has a complementary flange and is mounted on said operating head, a rim of said elastomeric membrane being clamped between the two flange surfaces.

13. A device as claimed in claim 12, wherein said container is provided with a cock to allow liquid to be discharged from the sides of elastomeric membrane containing said carrier liquid upon filling of the container with liquid to be admixed with the carrier liquid.

14. A liquid admixing device, substantially as hereinbefore described with reference to the accompanying drawing.