GB2129876A - Pulsation damper - Google Patents

Abstract

In order to provide a pulsation damper for use in pumped liquid flow lines, particularly where aseptic conditions have to be maintained, there is provided a pulsation damper in the form of a length of conduit having circular end zones 12 with unions 13 for connection to standard circular pipework. The pulsation damper itself consists essentially of a centre zone 14 of the length of conduit which is of non-circular sections so that it may flex under pressure towards the circular section and resiliently expanded to absorb the pulsations. The centre zone 14 is connected to the end zones 12 and merged into them by intermediate transition zones 15. Deflection limiters 21 may be provided at intervals along the centre zone 14. <IMAGE>

Description

SPECIFICATION Pulsation damper This invention relates to pulsation dampers.

In liquid flow lines the pumping of liquid tends to introduce a pulsation in the liquid pressure which can affect the operation of plant pipework.

Various forms of pulsation dampers are used, particularly the use of standpipes or accumulators in which the liquid level can vary to filter out the pulsation. Such arrangements do not lend themselves readily to operation in aseptic processes since they involve the use of dead areas where infection may grow and also there is a risk of non-sterile air working its way into the system via the pressure cushion in the standpipe.

It has also been proposed to use square section conduits for the pipework to eliminate pulsation by allowing the conduit to expand resiliently to adsorb pressure pulses. However such pipework is difficult to use in that it is not readily connectable to standard circular unions and is also wasteful of metal and therefore unnecessarily expensive, particularly is expensive metals such as stainless steel or titanium are being used. Further, the use of such pipework may lead to non-uniform flow and to dead spots which can become centres of infection in aseptic operations.

According to the present invention, there is provided a pulsation damper for use in a liquid flow line comprising a limited length of conduit of non-circular form adapted to flex resiliently towards circular form to absorb pressure pulses, the said length of conduit having end zones fitted with normal circular unions for connection to normal circular section pipework.

This invention will be further described with reference to the accompanying drawings, in which: Figure 1 is a diagram showing a typical application of a pulsation damper; Figure 2 is an elevation of a first form of damper in accordance with the invention; Figure 3 is a section on the line Ill-Ill of Figure 2; Figure 4 is a view similar to Figure 2 showing a modified form of pulsation damper; Figure 5 is a section on the line V-V of Figure 4; Figure 6 shows a modified shape of damper with a modified form of attachment of deflection limiters; Figure 7 is a section on the line VIl-VIl of Figure 6; and Figures 8 and 9, 10 and 11,and 12 and 13 are each respectively a perspective view and a section showing possible alternative shapes of pulsation damper.

Turning first to figure 1, there is shown a reservoir 1 for a liquid product 2 which is to be fed by a pump 3 to a processing stage generally illustrated at 4 to exit via pipework 5. In order to protect the processing stage 4 from the pressure pulsations introduced by the pump 3, a pulsation damper 6 is introduced at the output side of the pump as close as possible to the pump. Various types of pulsation damper have been proposed in the past, but a satisfactory accumulator or standpipe damper, which is the most convenient type, has not been obtainable for aseptic operation.

Turning now to figures 2 and 3, a damper illustrated consists of a length of conduit generally indicated by 11 and comprising end zones 12 of circular section of standard size and attached to unions 13 for connection to standard pipework. In the arrangement of figures 2 and 3, the main or centre zone 14 is of elongate section and merges into the end zones by means of transition zones 1 5. The cross sectional shape of the centre zone 14 is illustrated in figure 3 and will be seen to comprise a comparatively wide arcuate end portion 16, a comparatively narrow arcuate end portion 17 and rectilinear portions 18 merging into the portions 16 and 17 to form an elongated or pear-shaped section.For convenience of manufacture, the pulsation damper may be based on the standard pipework of which part is cut away to leave the wide arcuate portions 16, which would match the circular section of the end zones 12, and the cut away portion will be replaced by a welded-on fabrication consisting of the narrow end portion 17 and the rectilinear portions 18.

By way of example, the end zones 12 and the wide arcuate portion 16 may be based on one inch (25.4 mm) outside radius piping of stainless steel (16 swg) and the arcuate end portions 17 may have a radius of 8 mm while the rectilinear portions 18 of the section may be 100 mm long.

The centre zone 14 may for instance be 1 rn long.

It will be appreciated that as the centre zone 14 is designed to yield resiliently and flex with pressure pulsation, it will be capable of expanding towards circular section and thereby absorb pulsations introduced by the pump.

Turning now to figures 4 and 5, the configuration is substantially the same as in figures 2 and 3 except that a series of deflection limiters 21 have been placed around the centre zone 1 4 of the pulsation damper. These are in the form of discs having cut aways 22 substantially conforming at their ends to end portions 16 and 17 of the section of the centre zone 14, but having arcuate zones leaving a clearance from the rectilinear portions 18 to allow flexing, but at the same time limiting such flexing.

The deflection limiters are shown in figures 4 and 5 as being welded at 23 directly to the outside of both end portions 1 6 and 17 of the section of the centre zone 14. it may in fact be preferable for only one such weld to be used to allow the other end zone to separate from the deflection limiter when the rectilinear portions flex 18 outwardly.

Figures 6 and 7 show one possible alternative shape of pulsation damper, and also a modified mode of connection of the deflection limiters, which is usable over a wide range of shapes. The shape of the centre section 14 of the pulsation damper of figures 6 and 7 is a generally symmetrical oval having smooth rounded ends 17a. A deflection limiter 24 is shown in figure 7 as having a pair of central projections 25 to control movement of a central zone 26. In the region of each deflection limiter 24, a saddle 27 is welded around its whole periphery to the centre section 14 in the neighbourhood of the rounded ends 17a.

Welded to the saddle 27 are eye lugs 28, the welding extending along the whole base 29 of the eye lug 28. The eye lugs 28 are attached to the deflection limiter 24 by bolts passing through aligned holes, so that the limiter 24 may be detached from the pulsation damper.

A similar mode of fixing of the deflector limiters may be applied to the construction of figures 4 and 5.

Figures 8 and 9 shows a pulsation damper of the type generally described with reference to figure 6. It will be seen that instead of the one tapering portion 18, two are provided to form a common symmetrical formation with a greater potential for expansion. Figure 9 shows saddles 27 for attachment of the deflection limiters.

Figures 10 and 11 show an arrangement in which is of oval form which straight sides 31 and the transistors 15 are frusto-pyramidal.

Figures 12 and 13 show a centre section 14 which is of oval form which strain sides 31 and rounded ends 32.

The shapes illustrated are given by way of example only as virtually any non-circular shapes may be used. Deflection limiters may be used as required. The centre zone 14 may for instance be provided with longitudinal or transverse convolutions or fluting to provide for the controlled volume change in the unit.

Also, if required more than one pulsation dampener may be provided, connected either in series or parallel closely downstream of a pump, and/or upstream of a pump. Another alternative is to have a single unit each side of the pump.

Various other modifications may be made within the scope of the invention.

Claims (7)

1. A pulsation damper for use in a liquid flow line comprising a limited length of conduit of noncircular form adapted to flex resiliently towards circular form to absorb pressure pulses, the said length of conduit having end zones fitted with normal circular unions for connection to normal circular section pipework.

2. A pulsation damper as claimed in claim 1, in which the length of conduit has a centre zone adapted to flex and transition zones merging the centre zone smoothly into the end zones.

3. A pulsation damper as claimed in claim 2, in which the centre zone has a cross-section comprising arcuate ends of different widths joined by substantially straight lines merging into the arcuate ends.

4. A pulsation damper as claimed in claim 2, in which the centre zone is of square cross section.

5. A pulsation damper as claimed in claim 2, in which the centre zone is of symmetrical oval cross section.

6. A pulsation damper as claimed in any of claims 1 to 5, in which one or more deflection limiters are mounted on the non-circular length of conduit.

7. A pulsation damper substantially as hereinbefore described with reference to the accompanying drawings.