WO2017112976A1

WO2017112976A1 - A guard for a rotary pump

Info

Publication number: WO2017112976A1
Application number: PCT/AU2016/051248
Authority: WO
Inventors: Cesar Calma
Original assignee: Weir Minerals Australia Ltd
Priority date: 2015-12-30
Filing date: 2016-12-16
Publication date: 2017-07-06

Abstract

A guard for a rotary pump is described, the pump having a bearing housing and further including an impeller housing, and a driveshaft extending between the bearing housing of the pump and the impeller housing; the pump further including an adjustable sealing arrangement including a gland follower which is provided at a region where the driveshaft enters the impeller housing, the guard including: a bearing housing portion; and a gland follower portion; wherein the bearing housing portion includes an upper guard portion and a lower guard portion, the upper guard portion is arranged to be affixed to the bearing housing and retains the lower guard portion in place in association with the bearing housing; the gland follower portion is arranged to be attached to the gland follower, the gland follower portion cooperates with the bearing housing portion to accommodate changes in the adjustment of the gland follower; and wherein the guard allows access to adjust the sealing arrangement but obstructs access to the driveshaft.

Description

A GUARD FOR A ROTARY PUMP

Technical Field

This invention relates to guards used with machines to prevent injury to operators of the machinery. The invention has particular application to rotary pumps.

Background to the Disclosure

Operators of machines face the risk of injury by coming into contact with moving parts of the machine. For instance, if the hair or clothing of a machine operator were to become entangled with a moving part such as a rotating shaft, then the hair or clothing of the operator may quickly become quickly wrapped around the shaft and the operator can be quickly dragged towards and into contact with moving parts of the machine, which can give rise to very serious injuries. This risk exists during normal operation of the machine and whilst making maintenance inspections or adjustments. To reduce the risk of injury to machine operators or maintenance workers, a machine may be fitted with guards which obstruct access to moving parts. Compliance to Safety of Machinery as specified in standard AS4024.1801 prohibits the removal of guarding on rotating elements thus prevents gland adjustment while the pump is running. This represents both a cost and an inconvenience to plant operators or maintenance workers, as sometimes it is necessary to shut down a pump to remove the guard to carry out routine inspections or maintenance.

Rotary pumps typically comprise a bearing housing and an impeller housing, with a driveshaft extending between the bearing housing and the impeller housing. An adjustable gland seal is provided at the region where the driveshaft enters the impeller housing. The function of the gland seal is to resist escape of pumping medium, such as a slurry or liquid, from the pump whilst allowing for rotation of the driveshaft which supports and drives an impeller located inside the impeller housing. The gland seal is often provided with its own pressurised water supply and some amount of leakage of water or other fluid is normal during operation of the pump.

The gland seal typically includes some type of packing material which becomes compacted or worn over time. This necessitates regular inspection of the rate of leakage from the gland seal and the making of regular adjustments of the degree of compression applied to the packing material which is typically effected by progressive manual tightening of nuts or bolts which hold a gland follower in compressed relation to the packing material.

There remains a need for improved guard arrangements for use in association with the region surrounding the driveshaft and gland seal of a rotary pump.

Summary of the Disclosure

In a first aspect there is provided a guard for a rotary pump, the pump having a bearing housing and further including an impeller housing, and a driveshaft extending between the bearing housing of the pump and the impeller housing; the pump further including an adjustable sealing arrangement including a gland follower which is provided at a region where the driveshaft enters the impeller housing, the guard including: a bearing housing portion; and

a gland follower portion; wherein

- the bearing housing portion includes an upper guard portion and a lower guard portion, the upper guard portion is arranged to be affixed to the bearing housing and retains the lower guard portion in place in association with the bearing housing;

- the gland follower portion is arranged to be attached to the gland follower, the gland follower portion cooperates with the bearing housing portion to accommodate changes in the adjustment of the gland follower; and wherein

- the guard allows access to adjust the sealing arrangement but obstructs access to the driveshaft.

In some embodiments, the gland follower portion encircles and at least partially overlaps the bearing housing portion.

In some embodiments, the lower guard portion hangs from the upper guard portion.

In some embodiments, the upper guard portion is substantially C-shaped and the lower guard portion hangs from free ends of the C-shape.

In some embodiments, the C-shape of the upper guard portion describes an arc of approximately 270 degrees.

In some embodiments, the upper guard portion and lower guard portion include interengaging lips which prevent movement of the lower guard portion away from the bearing housing when installed on a pump.

In some embodiments, the gland follower portion is formed by at least two sections.

In some embodiments, at least two sections of the gland follower portion are joined by a hinge.

In some embodiments, the guard includes apertures to allow visual inspection of the driveshaft. In a second aspect, there is provided a rotary pump including a guard according to the first aspect.

In a third aspect, there is provided a method of retrofitting a guard to a rotary pump including the steps of providing a guard according to the first aspect, and installing the guard on the pump.

Other aspects, features, and advantages will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of inventions disclosed.

Brief Description of the Drawings

Notwithstanding any other forms which may fall within the scope of the disclosure as set forth in the Summary, specific embodiments will now be described by way of example and with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a guard in accordance with the present disclosure;

Figure 2 is an exploded view of the first sub-assembly of the guard of Figure 1;

Figure 3 is a perspective view of the first sub-assembly of the guard of Figure 1;

Figure 4 shows the second sub-assembly of the guard of Figure 1 in the open configuration;

Figure 5 shows the guard of Figure 1 installed on a rotary pump; and

Figure 6 shows the gland follower of the pump of Figure 5 being adjusted with the guard in place.

Detailed Description of Preferred Embodiments

Referring to Figure 1, a guard 10 for a rotary pump is shown. The guard 10 includes a bearing housing portion in the form of a first sub-assembly 20. The first subassembly 20 is comprised of an upper guard portion in the form of upper guard member 22, shaped from an arcuate strip of material, and a lower guard portion in the form of lower guard member 24 also shaped from an arcuate strip of material, which interfits in use with the upper guard member 22 to form a complete ring-shaped member. The first sub-assembly 20 is arranged to be affixed to the bearing housing of the pump using preexisting screws or bolts fitted by way of two apertures 26. The guard 10 further includes a gland follower portion in the form of a second sub-assembly 30. The second sub-assembly 30 is comprised of two semi-circular strip sections of material 32, 34 which are joined by a hinge 35 located centrally therebetween. The second sub-assembly is arranged to be affixed to the gland follower of the pump using pre-existing screws or bolts fitted by way of two apertures 36.

Referring to Figures 2 and 3, the sequence of installing and assembling the first sub-assembly 20 is shown. Referring firstly to Figure 2, the sub-assembly 20 is provided in two parts, the upper guard member 22 and the lower guard member 24 to allow the sub-assembly 20 to be installed about the driveshaft of a rotary pump. The lower guard member 24 is supported in place temporarily by hand beneath the driveshaft. The upper guard member 22 is then put in place in from above the driveshaft, and in a movement represented by dotted arrow D, the two parts 22, 24 are joined together in an interfitting manner as shown in Figure 3. Bolts are then inserted through respective apertures 26 into pre-existing threaded holes provided in the bearing housing of the pump to maintain the first sub assembly 20 in place.

As can be seen in the figures, the upper guard member is somewhat C-shaped insofar as it describes an arc of greater than 180 degrees. In the embodiment shown the upper guard member describes an arc of approximately 270 degrees. The result of this arrangement is that the upper guard member partially encircles the lower guard member so that the lower guard member hangs from the upper guard member. The distance between the free ends of the C-shaped profile must be sufficient to enable the free ends to accommodate the shaft of the pump during installation of the guard. When installed, the lower guard member 24 hangs below the upper guard member 22 by interfitting engagement at the regions labelled A and B. Furthermore, the outwardly projecting lip 28 provided on the lower guard member 24 interengages with the inwardly projecting lip 27 provided on the upper guard member 22 by becoming trapped behind the lip 27, to prevent the lower guard member 24 from moving outwardly from the bearing housing. In this way, the lower guard member 24 is held in place by the upper guard member 22 without the need for additional fasteners. The two bolts holding the upper guard member 22 serve to maintain the entire sub-assembly in place.

Referring to Figure 4, the second sub-assembly 30 is shown in isolation and in the open position with the two semi-circular strip sections 34, 32 swung away from each other about the hinge 35. To install the second sub-assembly, it is opened to the configuration shown in Figure 4 and then brought about the driveshaft of the pump. The sub-assembly is then closed by rotating the two sections towards one another, about the hinge 35. The catch 37 frictionally engages with the free end of section 32. Pre-existing bolts are then inserted through the two apertures 36 and into pre-existing threaded holes provided in the gland follower, so as to affix the second sub-assembly to the gland follower of the pump. This guard 10 is now complete as shown in Figure 1, installed on a pump with the second sub-assembly 30 encircling and overlapping the first subassembly 20. The second sub-assembly 30 encloses the upper and lower guard members 22, 24 and slides over the upper and lower guard members 22, 24 during gland adjustment.. Referring to Figure 5, the guard 10 is shown installed on a pump 1. The first sub-assembly 20 is affixed to the bearing housing 2 and the second sub-assembly 30 is affixed to the gland follower 4. Over time, the gland follower 4 must be adjusted to maintain the correct pressure on the packing inside the gland seal. This is achieved by periodically tightening the gland follower adjustment nuts 5 (one of which is visible in Figure 5 - another gland follower adjustment nut is provided on the other side of the gland follower but is not visible in the Figure). Both gland follower adjustment nuts 5 are tightened by the same amount of rotation to maintain the gland follower in a parallel relationship to the gland packing. Referring to Figure 6, the gland follower adjustment nut 5 is shown being tightened by use of a hand held spanner 6. As can be seen, the guard 10 provides access to adjust the gland follower 4 of the adjustable sealing arrangement, but obstructs access to the driveshaft to prevent injury to maintenance operators. Over time, progressive tightening operations on the gland follower adjustment nuts 5 take place as the gland packing in the gland seal wears away. This has the effect of the gland follower 4, and attached second sub-assembly 30, moving to the left as seen in Figure 5. However, because the second sub-assembly 30 overlaps the first subassembly 20, this movement does not result in exposure of the driveshaft and so safety of operators is ensured over time as the gland seal is adjusted.

The guard 10 also provides protection of the bearing seals from ingress as a secondary functi on .

Eventually the gland seal packing will wear to such an extent that it must be replaced. The operation of repacking the gland seal is carried out when the pump has been shut down and the drive shaft is not rotating. The guard 10 may be removed to carry out the operation of repacking the gland seal and is replaced afterwards.

Components of the guard 10 are formed from stainless steel but could also be formed from plain carbon steel which may be painted to inhibit corrosion. Inspection apertures are provided in the first and second sub-assemblies

(labelled 23 in Figure 2, and 33 in Figure 4). These apertures allow a visual inspection of the driveshaft region of the pump.

It can be seen the embodiments of guards have at least one of the following advantages:

• the guard provides access to adjust the gland follower of the adjustable sealing arrangement but obstructs access to the driveshaft to prevent injury to maintenance operators

• the upper portion of the bearing housing portion is C-shaped to partially encircle and support the lower portion. The upper portion and lower portion include interengaging lips which prevent movement of the lower guard portion away from the bearing housing when installed. The lower portion is thereby retained in place without the use of any fasteners in the lower portion.

• The upper portion of the bearing housing portion is held in place by utilising pre-existing fasteners provided on the pump thus allowing for retrofitting of guards to existing pumps.

· the second assembly provides ease of assembly with a snap closed design requiring no addition fasteners

• guard provides protection of the bearing seals from ingress as a secondary function In the foregoing description of preferred embodiments, specific terminology has been resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "front" and "rear", "inner" and "outer", "above", "below", "upper" and "lower" and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

In this specification, the word "comprising" is to be understood in its "open" sense, that is, in the sense of "including", and thus not limited to its "closed" sense, that is the sense of "consisting only of. A corresponding meaning is to be attributed to the corresponding words "comprise", "comprised" and "comprises" where they appear.

In addition, the foregoing describes only some embodiments of the invention(s), and alterations, modifications, additions and/or changes can be made thereto without departing from the scope and spirit of the disclosed embodiments, the embodiments being illustrative and not restrictive. Furthermore, invention(s) have been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention(s). Also, the various embodiments described above may be implemented in conjunction with other embodiments, for example, aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment.

Claims

1. A guard for a rotary pump, the pump having a bearing housing and further including an impeller housing, and a driveshaft extending between the bearing housing of the pump and the impeller housing; the pump further including an adjustable sealing arrangement including a gland follower which is provided at a region where the driveshaft enters the impeller housing, the guard including: a bearing housing portion; and

a gland follower portion; wherein

- the gland follower portion is arranged to be attached to the gland follower, the gland follower portion cooperates with the bearing housing portion to accommodate changes in the adjustment of the gland follower; and wherein the guard allows access to adjust the sealing arrangement but obstructs access to the driveshaft.

2. A guard according to claim 1, wherein the gland follower portion encircles and at least partially overlaps the bearing housing portion.

3. A guard according to either claim 1 or claim 2, wherein the lower guard

portion hangs from the upper guard portion.

4. A guard according to claim 3 wherein the upper guard portion is substantially C-shaped and the lower guard portion hangs from free ends of the C-shape.

5. A guard according to claim 4 wherein the C-shape of the upper guard portion describes an arc of approximately 270 degrees.

6. A guard according to any preceding claim, wherein the upper guard portion and lower guard portion include interengaging lips which prevent movement of the lower guard portion away from the bearing housing when installed on a pump.

7. A guard according to any preceding claim, wherein the gland follower portion is formed by at least two sections.

8. A guard according to claim 7, wherein the at least two sections of the gland follower portion are joined by a hinge.

9. A guard according to any one of the preceding claims, including apertures to allow visual inspection of the driveshaft.

10. A rotary pump including a guard according to any one of the preceding claims.

11. A method of retrofitting a guard to a rotary pump including the steps of

providing a guard according to any one of claims 1 to 10, and installing the guard on the pump.