PUMP VALVES

Abstract: A pump valve comprises a valve casing (5) with an entrance (2) and an exit (7) with a fluid flow passage passing from the entrance to the exit. The valve apparatus is contained within the casing (5) and is comprised of moveable member (4) slidably attached to a guide stem (1) mounted longitudinally relative to the fluid flow. The moveable member (4) carries a sealing means (3) which seats on a seating surface (14) located near the entrance (2) creating a seal. The moveable member (4) is of a density approximating that of the liquid being pumped.

Description: PUMP VALVES The present invention relates to an improved pump valve. Valves in plunger and or piston pumps for moving liquids often consist of discs or poppets which are spring loaded or of a higher density than the liquid being pumped to ensure rapid closing of the valves at the start and or finish of a plunger or piston stroke. Valves such as these have an inherent disadvantage in that part of the energy in the pressure and flow of the liquid is used up in overcoming the mass of the valve or the load of the valve spring and this energy loss is converted into heat and liquid velocity changes which can be a problem where the control of liquid temperature and or the likelihood of emulsification is important for example in the pumping of a mixture of oil and water. Hollow balls and or low density materials have been used in an attempt to overcome the problems outlined above but these have disadvantages. In the case of hollow balls they cannot be easily guided and turbulance is created on the downstream side of the ball. Low density materials on the other hand have the added disadvantage that they often have a restricted range of chemical and/or abrasion resistance. In its broadest form the present invention comprises an improved pump valve comprising a valve casing with a fluid entrance and an exit, a fluid flow passage through said valve casing, a valve seat, a guide stem mounted coaxially relative to the direction of fluid flow, a moveable member slidable on said guide stem, a sealing means between said valve seat and said moveable member; said moveable member being of a density approximating that of the liquid being pumped. In a preferred embodiment the slideable moveable member is assisted by a spring means and is of a similar density to the liquid being pumped. The moveable member is guided longitudinally relative to the liquid flow and is of streamlined configuration. The moveable member is activated by being carried along in the flow of the liquid. Preferably the density of the valve is as close as is possible to that of the liquid being pumped and may be of hollow construction to achieve this desirable relative density. The advantage of this invention is a reduction in liquid velocity changes which would normally give rise to turbulance, with the result that a more streamlined liquid flow is achieved. Thus the likelihood of emulsification of mixed liquids passing through the pump valve during pumping is reduced. The present invention will now be described in detail with reference to a preferred embodiment as shown in the accompanying drawings in which: Fig. 1 shows a cross sectional view of the valve in the closed position according to a preferred embodiment of the present invention; and Fig. 2 is a cross sectional view of the valve of Fig. 1 shown in the open position. With each stroke cycle of the pumps the valve operates as follows . The valve as shown in Fig. 1 is located at the suction or inlet 2 to the plunger (not shown) and also at the outlet or discharge of the pump (not shown) . When the plunger draws liquid into the pump chamber (not shown) on the inlet or suction stroke of the pump the moveable member 4 is lifted by the liquid flow from its sealing seat 3 by the liquid being drawn through inlet 2. The moveable member 4 lifts until stopped by top section 9 of moveable member 4 abutting against stop 12. This lifting action may be cushioned by a spring 6 which can also be used to start the valve in its downwards movement at the commencement of the outlet or discharge stroke of the pump. The liquid being pumped flows up the annular space between the moveable member 4 and the casing 5, this annular space is so designed as to provide as nearly as possible a uniform cross sectional area available for liquid flow along its path and is of a streamlined configuration so as to reduce the turbulance and heat created by direction and velocity changes, to a minimum. The liquid then flows through exit 7 and thence into the plunger chamber. When the plunger starts on its discharge stroke the liquid flows through exit 7 and in doing so carries the moveable member 4 along in its flow until the sealing means 3 contacts the seating surface 14 adjacent to the casing 5, when it again seals. During its movement the moveable member 4 is guided by a stem 1 at its longitudinal centre line and this stem is guided by a bush or seat in its mounting 11 and another bush or seat in its mounting 13 . The valve or as shown in Fig. 1 is also located at the outlet line and its operation is similar to that of the inlet valve except that the outlet valve closes on the inlet stroke of the pump and opens on the outlet stroke of the pump. Moveable member 4 may directly abut casing 5 or a seating material such as an 0 ring 3 as seen in Fig. 1 can be interposed. The valve may comprise a unit as described in Fig. 1 or may be incorporated in a valve block in which case the body or casing and flanges 8 and 10 would form part of a block also containing the other valve or valves in the pump. The casing 5 may be split to facilitate assembly. Fig. 2 shows moveable member 4 in its open position whereby the liquid being pumped has forced moveable member 4 along the stem 1 compressing the spring 6 thus allowing the liquid to pass around the said moveable member. Whilst a detailed description has been given of a single valve, it will be apparent that a plurality of valves may be used in practice. It will be recognised by persons skilled in the art that numerous variations and modifications may be made to the invention as described above without departing from the scope of the invention as defined by the following claims .

Claims: THE CLAIMS : 1. An improved pump valve comprising: a valve casing having a fluid entrance and exit, a fluid flow passage through said valve casing connecting said entrance and exit, a valve seat located within said fluid flow passage, a guide stem mounted co-axially relative to the direction of fluid flow within said fluid flow passage, a moveable member slidable on said guide stem, a sealing means between said valve seat and said moveable member; said moveable member being of a density approximating that of the liquid being pumped. 2. A pump valve as claimed in claim 1 wherein the slida b le moveable member is assisted by a spring means. 3. A pump valve as claimed in claims 1 or 2 wherein the sealing means is an annular ring. 4. A pump valve as claimed in any one of claims 1 - 3, wherein the sealing means abuts the surfaces of the moveable member and the valve seat. 5. A method of reducing the velocity changes and/or turbulence of a liquid being pumped by use of a pump valve as claimed in any one of claims 1 - 4. 6. A method of reducing the emulsification in a mixture of liquids being pumped by use of a pump valve as claimed in any one of claims 1 - 4. 7. A pump valve substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: MONTGOMERY COLIN ROBERT LISTER, MONTGOMERY, COLIN, ROBERT, LISTER
Applicants: MONTGOMERY PETER ROSS, MONTGOMERY, PETER, ROSS
Application year: 1985
Main classification: F04B21
IPC codes: F04B53, F16K15