GB2033470A

GB2033470A - Hand or foot pump for liquids

Info

Publication number: GB2033470A
Application number: GB7843363A
Authority: GB
Original assignee: BERELSON R
Current assignee: BERELSON R
Priority date: 1978-11-06
Filing date: 1978-11-06
Publication date: 1980-05-21
Also published as: GB2033470B

Abstract

A hand or foot pump primarily for dispensing caustic liquids in accurate amounts comprises bellows 1 in a casing having a flexible cover 11. The bellows 1 are biassed to an expanded condition and into contact with the cover 11 by a spring 8. Inlet and outlet passages in a casing part 3 and associated with respective non-return valves communicate with the interior of the bellows, which defines a liquid receiving chamber from which liquid is expelled by pushing on the cover 11. <IMAGE>

Description

SPECIFICATION Hand or foot pump for liquids The invention relates to a hand or foot-operated pump for dispensing liquids.

Such pumps, mostly operated by a plunger, are well known, for example for home and garden use, but they are not usually sufficiently accurate for dispensing a metered quantity of liquid per stroke, the capacity of the pump is not adjustable and, most important, the pump is rarely leakproof and therefore unsuitable for caustic liquids.

For industrial use, a hand-operated pump is known which works with a piston displaceable in a cylinder. To make the pump leakproof initially, an O-ring is provided between the piston ring and the cylinder. However, the ring is subject to rapid decay, whereafter caustic liquid, if such is being pumped, can escape through an air vent hole that is necessarily present in a cylinder cover.

The present invention aims to provide a cheap hand or foot-operated pump which,can dispense accurate quantities of liquid, is safe for use with caustic liquids despite an extremely economical construction and, in its preferred form, has provision for changing the pumping capacity.

According to the invention, a hand or foot pump for dispensing liquids comprises compressible bellows defining a liquid-receiving chamber in its interior and contained in a casing of which the first part has an open end of the bellows secured to it and has an inlet and outlet passage communicating with said chamber and a second casing part is in the form of a flexible cover connected to the first part, a non-return valve associated with each inlet and outlet passage and a compression spring acting between a closed end of the bellows and the first casing part to bias the bellows to an expanded condition and hold the closed end of the bellows in contact with the cover.

The first casing part will constitute either a base in the case of a foot pump, or a back wall in the case of a, say, wall-mounted hand pump.

The pump according to the invention is operated by depressing the flexible cover, which results in compressing the bellows and ejecting the contents from its liquid-receiving chamber through the outlet passage. The spring automatically causes the bellows to execute their expansion stroke and at the same time return the flexible cover from its depressed condition. During the expansion stroke, liquid is drawn into the chamber through the inlet passage. The non-return valves ensure that liquid flows only in the desired direction.

By means of the invention, no difficulties are encountered in providing a reliable seal to prevent liquid from weeping to the exterior of the casing because the liquid is inside the bellows and the latter are shielded by the flexible cover. Also, the bellows are unlikely to become punctured because the actuating force is applied to them through the cover Desirably, the casing parts are releasably interconnected so as to permit access to be obtained to a substantially C-shaped or partcircular ring which is disposed in the last trough of the bellows corrugations to cooperate with the first casing part and constitute a stop for positively limiting the amount of bellows compression. By changing the Cring for one which is thicker or thinner, the compression stroke and hence the intake and pumping capacity of the bellows can be altered.

An example of the invention is illustrated in the accompanying drawings, wherein: Figure 1 its a side elevation of portion of a hand or foot for caustic liquids and Figure 2 is a sectional side elevation of the complete pump.

The illustrated pump comprises compressible bellows 1 having a flange 2 at an open end clamped to a first casing part 3 by a securing ring 4 of the part 3, a liquid-tight seal being afforded by an annular seal 6 which could be heat-sealed to a ridge on the part 3. The other end of the bellows is closed and provided with an internal locating support 7 for one end of a compression spring 8, of which the other end is seated in an emplacement 9 in the casing part 3. A second casing part 11 is in the form of a flexible cover or shield which could be permanently secured to the casing part 3 but is preferably releasably connected thereto by a clamp 1 2 known as a Jubilee clip. The spring 8 biasses the bellows 1 to an expanded condition and holds the closed end in contact with the cover 11.For use as a foot pump, the casing part 3 would extend horizontally and form a base. In the illustrated vertical position, the part 3 may be suitably mounted on a wall.

The casing part 3 contains an inlet passage 1 2 and an outlet passage (not visible), both in communication by way of a connecting recess 1 3 with the interior of the bellows 1, which defines a liquid-receiving chamber. The inlet passage 1 2 leads to a tapped socket 14 with which a non-return inlet ball valve housing 1 6 is in a screw-threaded engagement, which is liquid-tight by means of a ring seal 1 7. The housing 1 6 is provided with a externally screw-threaded nipple 1 8 for connection to a conduit (not shown). In an analogous manner, the invisible outlet passage leads to a socket receiving a non-return outlet ball valve housing 19 having a screw-threaded nipple 21.

The pump is operated by depressing the cover 11 by hand or foot, as the case may be, to compress the bellows 1 by moving its closed end towards the casing part 3. Liquid is thereby expelled from the liquid-receiving chamber within the bellows through the recess 1 3 and out through the nipple 21.

During this time, liquid is prevented from leaving through the nipple 1 8 by the nonreturn valve associated with the inlet passage 1 2. The compression stroke of the bellows is limited by a part-circular, preferably C-shaped, abutment ring diagrammatically indicated at 22 adjacent the securing ring 4 of the casing part 3. In practice, the bellows are constructed differently from the illustrated version so that the abutment ring 22 can be sprung around the bellows into an end trough of the bellows corrugations. During the expansion stroke of the bellows, effected by the spring 8 when the hand or foot is removed from the cover 11, liquid enters the bellows 1 through the inlet nipple 18 but cannot be sucked back through the nipple 21 by reason of the nonreturn outlet valve.

If the cover 11 is releasably secured to the casing part 3, access can be obtained to the abutment ring 22 to replace it for a thicker or thinner ring and thereby alter the bellows compression stroke and hence the amount of liquid taken in during the expansion stroke.

The main components of the pump can be readily made from inert plastics material to provide a cheap construction which is nevertheless reliable and accurate and avoids the sealing problems encountered with conventional plunger and piston-operated pumps.

Claims

1. A hand or foot pump for dispensing liquid comprising compressible bellows defining a liquid-receving chamber in its interior and contained in a casing of which a first part has an open end of the bellows secured to it and is provided with an inlet and outlet passage communicating with said chamber and a second casing part is in the form of a flexible cover connected to the first part, a non-return valve associated with each inlet and outlet passage, and a compression spring acting between a closed end of the bellows and the first casing part to bias the bellows to an expanded condition and hold the closed end of the bellows in contact with the cover.

2. A pump according to claim 1, including an abutment ring disposed in a trough of the bellows corrugations to co-operate with the first casing part and constitute a stop for positively limiting the amount of bellows compression.

3. A pump according to claim 2, wherein the cover is releasably connected to the first casing part.

4. A pump according to any preceding claim. wherein the closed end of the bellows is provided with an internal locating support for one end of the spring and the first casing part is provided with an emplacement for the other end of the spring.

5. A pump according to any preceding claim, wherein the inlet and outlet passages extend from a common connecting recess in the first casing part in communication with the open end of the bellows.

6. A pump substantially as hereinbefore described with reference to the accompanying drawings.