GB2201465A

GB2201465A - Fluidic pumping system

Info

Publication number: GB2201465A
Application number: GB08704214A
Authority: GB
Inventors: Geoffrey Hugh Priestman; John Russell Tippetts
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 1987-02-24
Filing date: 1987-02-24
Publication date: 1988-09-01
Anticipated expiration: 2007-02-24
Also published as: GB2201465B; GB8704214D0

Abstract

A fluidic pumping system incorporating a RFD (reverse flow diverter) in which means having a high resistance to back- flow is included in the inlet flow to the RFD. The high resistance means can be a diffuser or a vortex diode (Figure 2). <IMAGE>

Description

Improvements in fluidic pumping systems The present invention concerns fluidic pumping systems.

Fluidic pumping systems incorporating RFD (reverse flow diverter) component parts are known, for example, see UK Patent Specification No 1,480,484. In such pumping systems, which can be single-acting or double-acting, an alternating pressure and flow across the or each RFD effects entrainment of liquid to be pumped. However, at the point at which alternate pressurisation phases change there appears a momentary backflow, from the or each RFD, of liquid being pumped and this results in a reduction in the overall performance of the pump.

Accor-ding to the present invention and to improve the performance of a fluidic pumping system incorporating an RFD means having a high-resistance to back-flow is provided in the flow path of liquid being pumped into the RFD.

The invention will be described further, by way of example, with reference to the accompanying schematic drawings; in which: Figure 1 illustrates a first embodiment of a fluidic pumping system; and Figure 2 illustrates a second embodiment.

Figure 1 illustrates one form of double-acting fluidic pump which comprises two displacement vessels 1 and 2s RFD 3 and a Y-joint 4 referred to as a flow junction (FJ). RFD 3 communicates through pipe 5 with a supply of liquid to be pumped, such as liquid 6 in tank 7.

In operation, liquid in the displacement vessels 1 and 2 is pushed up and down in anti-phase by air pressure and the to-and-fro flow across the RFD and the FJ is converted into a continuous pumped flow in delivery pipe 8 from the supply tank 7.

An unwanted pulse of "backflow" results in the pipe 5 upon changeover in the displacement vessels. A pulse of flow is lost twice during each full pump cycle with a consequent reduction in overall pump performance. To minimise such backflow a diffuser 9, that is a converging and then a slowly diverging venturi-like duct, is placed in the pipe 5. The diffuser 9 is arranged such that its throat is away from the RFD as shown in Figure 1. The diffuser therefore offers a low resistance to flow into the RFD from the supply tank 7 and a high resistance to back flow in the opposite direction. For greatest effect it is necessary to match the size of the diffuser to the pumping system and conveniently the diameter of the diffuser throat can be arranged to be about a half of the diameter of the RFD throat.

An alternative arrangement is shown in Figure 2 which utilises a vortex diode 10 to perform the same function as the diffuser in Figure 1. The diode is arranged in the pipe 5 with its tangential port connected to the entrainment port of the RFD and its axial port connected to the tank 7. The diode functions as a non-return valve to resist back-flow from the RFD to the tank 7.

The diffuser and vortex diode are two examples only of possible means for inhibiting back flow. Likewise the FJ-RFD is but one example of a double acting fluidic pump and the use of a back flow retarder will be beneficial in other types of fluidic pumps, both single-acting and double-acting, which incorporate RFD component parts.

Claims

1. A fluidic pumping system incorporating a reverse flow diverter in which means having a high resistance to back-flow is provided in the pumped flow path into the reverse flow diverter.

2. A fluidic pumping system as claimed in claim 1 in which the high resistance means comprises a diffuser having its throat arranged away from the reverse flow diverted.

3. A fluidic pumping system as- claimed in claim 2 in which the diameter of the diffuser throat is approximately a half of the diameter of the throat of the reverse flow diverter.

4. A fluidic pumping system as claimed in claim 1 in which the high resistance means comprises a vortex diode.

5. A fluidic pumping system substantially as herein described with reference to and as illustrated in Figure 1 or Figure 2 of the accompanying drawings.