WO2007021845A2

WO2007021845A2 - Fill port for a self-priming centrifugal pump, with safety device

Info

Publication number: WO2007021845A2
Application number: PCT/US2006/031205
Authority: WO
Inventors: James G. Shaw; James Northrup
Original assignee: Envirotech Pumpsystems, Inc.
Priority date: 2005-08-10
Filing date: 2006-08-10
Publication date: 2007-02-22
Also published as: BRPI0614332A2; WO2007021845A3; AU2006279949A1; EP1915534A2; CN102155427A; CA2618419C; AU2006279949B2; CN102155427B; US20070071619A1; CA2618419A1

Abstract

A safety cover for the fill port of a self-primer pump is structured to improve the seal between the fill port cover and the fill port in the pump casing to thereby control the release of steam from the pump, and includes an improved sealing band between the fill port and fill port cover, an improved fill port cover design and an improved retaining clamp design.

Description

FILL PORT FOR A SELF-PRIMING CENTRIFUGAL PUMP, WITH

SAFETY DEVICE

Cross-reference to Related Application: This application is a non- provisional application claiming priority to provisional patent application Serial No. 60/707,097 filed August 10, 2005.

BACKGROUND OF THE INVENTION

Field of the Invention: This invention relates to self-primer centrifugal pumps, and specifically relates to a fill port assembly having improved safety construction.

Description of Related Art: Self-priming centrifugal pumps are well- known and frequently used in industries where processing fluids with entrained solids is required. Self-primer pumps, also known as trash pumps, are characterized as having a casing which houses a suction chamber and a separation chamber divided by a wall or plenum. An impeller positioned in a volute section of the pump receives fluid from the suction chamber and delivers it by centrifugal action into the separation chamber where it is eventually expelled through an outlet.

In operation of a self-primer pump, fluid enters through an inlet into the suction chamber of the pump. A check valve is positioned to seat against the inlet in a manner such that while the pump is operating, the check valve remains open; but when the pump stops, the check valve will seat against the inlet opening to prevent fluid from leaving the suction chamber of the pump. If the check valve remains open or does not seat properly against the inlet, fluid is siphoned back out of the suction chamber until the siphoning action, or leg, is broken. As a result, the fluid level in the suction chamber is very low making re-priming of the pump very difficult. It is desirable, therefore, to assure that fluid remains in the suction chamber.

Self-primer pumps are conventionally structured to keep as much fluid in the pump as is necessary for re-priming. However, low fluid levels may occur for a number of reasons, including back siphoning of fluid from the pump. If the fluid levels are low and the pump will not prime (i.e., pull fluid up through the suction piping into the pump), the pumping action of the pump can turn what water does exist in the pump into steam.

Self-primer pumps are often constructed with a fill port, usually near or at the top of the pump casing, which allows access for adding fluid to the pump. Accessing the interior of the pump through the fill port can be extremely dangerous, however, especially when the pump fails to prime and turns the water in the pump into steam. Removing the cover of the fill port can result, and has resulted, in significant to severe injury, usually due to steam escaping through the fill port. Consequently, safety covers have been developed for the fill port in an attempt to reduce accidents and injury. Despite these efforts, numerous injuries continue to occur due to the design of the safety cover.

Thus, it would be advantageous in the art to provide a safety cover for the fill port of a self-primer pump that prevents injury and accidental exposure to steam exiting from the pump under the conditions noted.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, a safety cover for the fill port of a self-primer pump is provided which improves the seal between the fill port cover and the fill port in the pump casing and which assures securement of the fill port cover to the fill port during release of steam from the pump so that injury can be avoided.

The fill port cover and safety device of the present invention generally comprises a cover for occluding the fill port of the pump, a retaining clamp and an anchor bolt positioned between the retaining clamp and the fill port cover, as is conventionally known. However, the fill port cover of the present invention is configured with a depression to receive the end of the anchor bolt in a manner that assures that the fill port cover will remain in place positioned above the fill port when steam is released under pressure from the pump casing. The safety device also comprises a sealing band which is positioned between the fill port and the fill port cover. The sealing band may be configured as an o-ring, which provides improved steam release from the fill port. The o-ring may, most suitably, be coated with Teflon^®, or otherwise treated with or made from a material that imparts a non-adherent quality to the sealing band.

The retaining clamp of the safety device of the present invention may also be structured with recesses or depressions at either end of the retaining clamp in order to accommodate the head of a socket cap head screw in the retaining clamp as the clamp is connected to the pump casing. The depressions retain the head of the screws and prevent the retaining clamp from releasing away from the screws or the fill port cover.

The three safety elements of the present invention may be employed together or in various combinations to provide a fill port cover that is structured to assure that the fill port cover releases steam from the pump at a more controlled rate than is possible in prior art systems. The safety . elements also assure that the fill port cover is not blown or jettisoned away from the fill port of the pump casing under release of high pressure steam from the pump.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, which illustrate what is currently considered to be the best mode for carrying out the invention:

FIG. 1 is a view of an upper portion of a prior art self-primer pump illustrating the fill port and an exploded view of the fill port cover of a conventional prior art pump;

FIG. 2 is a view of the fill port cover shown in FIG. 1 when the cover is in place over the fill port;

FIG. 3 is a plan view of the fill port shown in FIG. 2;

FIG. 4 is a view of an upper portion of a self-primer pump illustrating in an exploded view the fill port and safety device of the present invention; FIG. 5 is a view of the fill port and safety device of the present invention when the safety cover is in place over the fill port; and

FIG. 6 is a view in cross section of the fill port and safety device shown in FIG. 5, taken at line 6-6.

DETAILED DESCRIPTION OF THE INVENTION The fill port safety device of the present invention is best illustrated by a comparison with conventional fill port covers, an example of which is depicted in FIGS. 1-3. In particular, FIG. 1 illustrates the top of a pump casing 10 having a fill port 12 positioned near the outlet 14 of the pump. The prior art closure 16 of the fill port 12 comprises a flattened gasket 18 that is sized to fit about the fill port 12 opening and is positioned to be held in place by a fill port cover 20. A retaining clamp 22 is provided for positioning over the fill port cover 20 and is secured to the pump casing 10 by square-head bolts 24, 26 that threadingly connect to threaded holes 28, 30 in the pump casing 10 located on either side of the fill port 12. The retaining clamp 22 is configured with U-shaped openings 32, 33 at either end of the clamp 22 to receive the bolts 24,26.

An L-shaped anchor bolt 34 is threaded through a central opening 36 in the retaining clamp 22. As best seen in FIG. 2, which illustrates the fill port cover 20 secured in position to close the fill port 12, the terminal end 38 of the anchor bolt 34 is brought into registration against the top surface 40 of the fill port cover 20. Tightening of the anchor bolt 34 against the fill port cover 20 provides pressure on the flat gasket 18 to assure a water-tight seal about the fill port 12.

As further illustrated in FIG. 3, securement of the retaining clamp 22 in prior art fill port systems is further accomplished by tightening the squarehead bolts 24, 26 so that there is a maximum distance D between the outermost corners of the heads of the two bolts 24, 26. Additionally, the retaining clamp 22 of the prior art is configured with a raised shoulder 42, 44 at the terminal end of the respective U-shaped openings 32, 33 of the retaining clamp 22. The raised shoulders 42, 44 presumably prevent the retaining clamp 22 from being released from the bottom of the heads of the bolts 24, 26 until the anchor bolt 34 is loosened approximately an eighth of an inch. It should be noted, however, that in prior art pumps the tightening of the bolts 24, 26 requires screwing the bolts 24, 26 until they bottom out in their respective threaded holes 28, 30, which can result in the squared heads not being adjusted to the maximum distance D. Further adjustment of the bolts 24, 26 to achieve the proper distance D can lead to either stripping of the threads in the bolts and/or creation of excessive pressure on the shoulders 42, 44 which results in potential leakage.

The foregoing described elements of the prior art fill port closure 16 are intended to keep the fill port cover 20 in place and to prevent injurious release of steam from the fill port 12 under conditions where steam is present in the pump. In operation, the anchor bolt 34 is loosened slightly (i.e., an eighth of an inch) to allow the fill port cover 20 to open slightly to release any steam from the fill port 12. However, it has been observed that the flattened gasket 18 of the prior art allows too much steam to escape from the fill port 12. The resulting release of steam pressure through the space between the gasket and the fill port cover 20 as the fill port cover 20 is loosened can cause the fill port cover 20 to be jettisoned away from the fill port 12, thereby causing injury.

Additionally, while the shoulders 42, 44 on the retaining clamp 22 are intended to contact the heads of the bolts 24, 26 to prevent a release of the retaining clamp 22, it has been found that loosening the anchor bolt 34 can not only cause the retaining clamp 22 to rotate, but can cause the retaining clamp 22 to tilt sufficiently to release at least one of the bolts 24, 26 from its respective shoulder 42, 44 resulting in a dangerous release of the retaining clamp 22 from the bolts 24, 26. Release of the retaining clamp 22 in this manner also results in a jettisoned release of the fill port cover 20 under conditions of elevated pressure from the steam.

In the fill port cover and safety device of the present invention, illustrated in FIGS. 4-6, these problems are solved by a number of structural changes. First, the present invention employs a sealing band 48 that is structured to better control the release of steam from the fill port. Most suitably, the sealing band 48 is an o-ring 50 that is positioned about the fill port 12 and is held in place by a fill port cover 52. It has been demonstrated that an o-ring sealing band 50 provides a more comprehensive water-tight seal with a reduced pressure requirement as compared to the flattened gasket used in the prior art.

The o-ring 50 may also be coated with, or otherwise treated or made from, a material that imparts non-adherent qualities to the sealing band 48, such as, for example, Teflon^®. The configuration and the non-adherent nature of the sealing band 48 provides better control of steam release such that when the fill port cover 52 is loosened slightly, any steam exiting from the pump will be released in a more even flow and distribution, thereby reducing the possibility for injury.

Second, the fill port cover 52 of the present invention is structured with a depression 54 formed in the top surface 56 of the cover 52 to accommodate the terminal end 58 of the anchor bolt 60. As shown in FIG. 6, when the anchor bolt 60 is threaded through the central opening 64 of the retaining clamp 62, the terminal end 58 of the anchor bolt 60 rests in the depression 54 of the fill port cover 52. This arrangement assures that the fill port cover 52 will remain positioned over the fill port 12 and against the sealing band 48 when the anchor bolt 60 is loosened because the depression 54 of the fill port cover 52 is unable to clear the terminal end 58 of the anchor bolt 60. Consequently, the fill port cover 52 is prevented from being blown off the fill port 12 under pressure as the steam escapes. The registration of the anchor bolt 60 within the depression 54 of the fill port cover 52 also assures more even pressure applied by the fill port cover 52 to the o-ring 50.

In the retaining clamp 62 of the present invention, socket cap head screws 66, 68 are used to attach the retaining clamp 62 to the pump casing 10. The retaining clamp 62 is configured with depressions 70, 72 at either end of the retaining clamp 62 into which the head 74, 76 of the socket cap head screws 66, 68 fit, as best seen in FIG. 6. This design feature assures that the retaining clamp 62 will not be released by or disengaged from the socket cap head screws 66, 68 when the anchor bolt 60 is loosened because the positioning of the head 74, 76 of the screws 66, 68 in the depressions do not allow the retaining clamp 62 to rotate, or to tilt appreciably. Further, the design feature assures that the retaining clamp 62 will not be released by or disengaged from the socket cap head screws until the top 78 of the retaining clamp 62 clears the bottom of the heads of the screws 66, 68.

The improved structural elements of the fill port cover and safety device of the present invention are each effective in assuring that the fill port cover 52 is retained in place above the fill port when steam is being released from the fill port. Any one of the improved structural elements described herein, including the improved sealing band 48, fill port cover 52 with depression 54 and improved retaining clamp 62 configuration may be employed alone or in combination with the other structural elements to provide improved safety in self-primer pumps. Variations in structure and configuration of the elements of the present invention may be introduced or employed to adapt the fill port cover and safety device to specific needs or applications. Thus, reference herein to specific details of the elements of the fill port cover with safety device are by way of example, and not by way of limitation.

Claims

CLAIMS What is claimed is:

1. A fill port safety assemblage for a self-priming pump, comprising: a fill port cover structured for positioning over the fill port of a self-primer pump, said fill port cover having a depression formed in the top thereof; a sealing band for positioning against said fill port cover ; a retaining clamp for positioning over said fill port cover to secure said fill port cover to a fill port; and an anchor bolt positioned through said retaining clamp, said anchor bolt having a terminal end sized for being received in said depression of said fill port cover.

2. The fill port safety assemblage of claim 1 where said sealing band is a o-ring.

3. The fill port safety assemblage of claim 2 wherein said o-ring has non-adherent qualitites.

4. The fill port safety assemblage of claim 3 wherein said o-ring is coated with Teflon^®.

5. The fill port safety assemblage of claim 1 wherein said retaining clamp is formed with a depression at either end of said retaining clamp to receive the head of a cap screw.

6. The fill port safety assemblage of claim 5 wherein said sealing band is formed as an o-ring.

7. The fill port safety assemblage of claim 6 wherein said o-ring is formed with non-adherent qualities.

8. A fill port safety assemblage for a self-priming pump, comprising: a fill port cover structured for positioning over the fill port of a self-primer pump; an o-ring for positioning between said fill port cover and the fill port of the pump; and a retaining clamp for positioning over said fill port cover to secure said fill port cover over the fill port.

9. The fill port safety assemblage of claim 8 wherein said o-ring is made of a material which imparts a non-adherent quality to said o-ring.

10. The fill port safety assemblage of claim 8 wherein said o-ring is treated to have a non-adherent quality.

11. The fill port safety assemblage of claim 10 wherein said o-ring is coated with Teflon^®.

12. A fill port safety assemblage for a self-priming pump, comprising: a fill port cover structured for positioning over the fill port of a self-primer pump; a sealing band for positioning between said fill port cover and the fill port; and a retaining clamp having two opposing holes for receiving screws therethrough, said holes each having a depression associated therewith for receiving the head of a cap screw through said opposing holes for securing said retaining clamp to a pump casing.

13. The fill port safety assemblage of claim 12 further comprising an anchor bolt positionable through said retaining clamp, and further wherein said fill port cover has a depression formed in the top of said fill port cover for receiving a terminal end of said anchor bolt.

14. The fill port safety assemblage of claim 12 wherein said sealing band is an o-ring.

15. The fill port safety assemblage of claim 14 wherein said o-ring has a non-adherent quality.