GB2318305A

GB2318305A - Suction strainer for a hose

Info

Publication number: GB2318305A
Application number: GB9621750A
Authority: GB
Inventors: Michael Avery; Simon Avery
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-10-18
Filing date: 1996-10-18
Publication date: 1998-04-22
Anticipated expiration: 2016-10-18
Also published as: GB9621750D0; GB2318305B

Abstract

A suction strainer/filter system 10 suitable for a hose comprises a woven strainer 12 through which liquid can flow and a connector 18 for sealingly connecting the woven strainer 10 to the end of a hose. The woven strainer 10 may have a warp of parallel metal or plastics stakes (20, 22 fig 4), a plastics weft and may be strengthened by support rings 14. A plurality of such strainers may be placed inside each other for extra filtration or in case one of the strainers fails, and an internal strainer may be raised from the ground level so only water down to a defined level is pumped away, leaving behind only the thicker sludge level (fig 8). A strainer may also be placed inside a hose (fig 9). The strainer 10 can be used when pumping water from flooded houses or in collecting water from ponds.

Description

SUCTION STRAINER The present invention relates to a suction strainer.

Suction straining is a method of vacuum pumping used by the Fire Brigade to draw water into the pump tanks of a fire engine from an outside source.

Primarily, the method is used to obtain water from a source such as a lake, pond, pool, known as "standing water" to maintain the on-board water level for use in putting out fires. (If this option is not available, the soft delivery hose of the fire engine may be connected to the domestic water mains supply.) In addition, this method of suction pumping may also be used to remove water from a house or other building which has been flooded or to drain water from a ship or other vessel.

The components used for suction straining by the Fire Brigade have been standardized throughout the United Kingdom. Depending on the size of pump used, suction may be via a 4 inch or a 5 inch solid suction hose. To prevent contaminants entering the suction hose which would present the risk of damage to the pump, a metal strainer is coupled onto the collecting end (the end to be placed in the water) of the hose.

The construction of the metal strainer is governed within BS 336, the British Standard Specification for fire hose couplings and ancillary equipment. The metal strainer has a female rounded screw thread over a cylindrical section made of a perforated sheet. The metal strainer must have holes sized to permit a defined rate of flow of water governed by present regulations and pump size. In addition, the holes of the metal strainer must be capable of preventing large solid objects from entering the pump.

If the metal strainer itself were placed in a pond, there would be a risk of the metal strainer becoming entangled with, lodged in or collecting soft mud, silt or other unknown debris below the surface of the water. The metal strainer is therefore placed in a willow suction strainer basket. A green canvas sleeve tied to the open end of the strainer basket is also tied above the hose coupling to secure the strainer basket to the hose. The green canvas sleeve also has some effect in preventing the backfill of water through the otherwise open end of the strainer basket between itself and the metal strainer.

It will be appreciated that, as indicated above, the construction of the suction components used must allow water to pass through at a sufficient rate for the requirements of the Fire Brigade. The components must be of sufficient strength to withstand the pressures generated by such flow rates. In addition, the components must be resistant to degradation caused by immersing the components in water, which may be salt water. Finally, the components should be easily handled and assembled by fire fighters or other end user without the need for complicated or intricate handling.

One problem with the use of willow strainer basket is that they are not particularly strong and can be damaged after only a few uses. The consequence of such damage is that a small stone, or other piece of debris, may pass through the damaged basket, through the metal strainer and into the pump system where it can cause considerable damage.

According to the present invention there is provided a suction strainer/filter system for a hose comprising a woven strainer through which liquid can flow and a connector for sealingly connecting the woven strainer to a hose.

The inventors were the first to realize that a suction strainer/filter system having features which allow direct connection to a suction hose would provide a better suction strainer/filter system which, in use, would be more able to protect the pumping equipment than prior art suction strainers.

The present invention therefore provides such a direct connection and improved suction strainer basket which may be used with the existing system. A cover plate which can be sealed to the open ends of an inner and an outer woven strainer/filter provides part of such a direct connection.

It is envisaged that the combination of strainers/filters with the direct connection could be sufficient to replace the prior art metal strainer, willow strainer basket and canvas sleeve.

In a further modification of the present invention, the length and circumference of the strainer/filter unit is altered. The strainer/filter unit is placed in a metal tube which exposes only the bottom 35 mm or so of the woven section of the outer strainer/filter unit when the unit is stood upright. A high-suction low-level strainer/filter is thereby produced through which the required flow rate of water is achieved while sand is the only solid object allowed to pass through the strainer/filter unit. The dimensions of the system, its length and circumference etc., are solely dependent on the requirements of the end user relating to its overall size within a pumping system and to the general operational requirements.

A further modification of the present invention provides a woven strainer/filter which can be enclosed within a soft hose to prevent debris from entering the system when the soft hose is used to draw water from a domestic water supply.

Advantageously, a region of the woven strainer is closed by a third rigid member to provide additional strength.

The rigid members are preferably made of wood coated by a suitable paint to allow the woven strainers to be immersed in water for an extended period. Other suitable materials such as alloy, plastics or other durable compounds may be used.

The woven strainer may have a warp formed by a plurality of parallel stakes which may be made of zinc-plated metal, stainless steel, a suitable plastics material or any other suitable rigid compound. For ease of construction and strength, the woven strainer has a right circular cylindrical shape with an open end and with rigid members at either end and spaced at regular intervals in between. It is expected that the woven strainer will have a circular cross-section although other cross-sections are possible and may be envisaged.

Preferably, the woven strainer has a weft formed by a plastics material which may be polypropylene extruded cane. Such materials are resistant to damage by water and can be woven as required.

In one embodiment, the connector comprises a round thread connection for connection to a hose and an adapter plate for closing the open end of the strainer. The adapter plate in combination with the rigid perimeter ring of the woven strainer provides a seal of sufficient hermeticity to permit water to be sucked through the suction hose at the required rate.

The adapter plate may include a side wall for overlapping the side of the rigid perimeter ring of a woven strainer. An annular portion of the adapter plate may overlap the side of the rigid perimeter ring of a woven strainer and be sealed to such side using washer of flexible material. Alternatively, or in addition, the adapter plate may include a plate portion at which a woven strainer is attached to the adapter plate.

Preferably, the suction strainer/filter system comprises a plurality of woven strainers so that even if one woven strainer is damaged, debris is prevented from entering the pump system by the remaining intact woven strainers. The innermost woven strainer may hav a finer mesh for better filtration. Where a pluralit of woven strainers are provided, at least one of the woven strainers may have a closed region closed by a rigid member but it may not be necessary for the other woven strainers to have such a closed region closed bo a rigid member.

The plurality of woven strainers may comprise an external woven strainer having said closed region and one or more internal woven strainers inside of the external woven strainer. Alternatively, the pluralit of woven strainers may comprise an external woven strainer having a second open region with a rigid support ring and an internal woven strainer inside of the external woven strainer, the internal woven strainer having a closed region closed by a rigid member.

Embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings: Figure 1 shows a woven strainer for use with an embodiment of the present invention; Figures 2 and 3 show the woven structure of first and second examples of the woven strainer of Figure 1 Figure 4 shows a plan view of the woven strainer of Figure 1; Figures 5 and 6 show further details of the construction of the woven strainer of Figure 1; Figure 7 shows a connector for connecting a woven strainer to a hose in accordance with an embodiment of the present invention; Figure 8 shows a low level strainer for use in pumping out water from a flooded building; and Figure 9 shows a schematic view of a woven strainer for use within a hose.

Figure 1 shows a woven strainer 10 having a right circular cylindrical shape in which woven sections 12 are interspersed with support rings 14. The woven strainer 10 includes a rigid base 16 and a rigid perimeter ring 18, the perimeter ring 18 allowing the woven strainer 10 to be sealingly connected with a fire hose.

For ease of illustration, the weave of the woven sections 12 has not been shown in Figure 1. Reference is made to Figures 2 and 3 which are derived from photographs of the woven sections 12 between support rings 14. The woven section of Figure 3 differs from the woven section of Figure 2 in that a plastic cane of a different cross-sectional area has been used.

The weave of the woven sections 12 has been chosen to satisfy the requirement that the holes in the weave be sufficiently small to prevent solid debris above a certain size from passing through. It is expected that the woven sections must be capable of preventing all stones from passing through. In addition, the weave of the woven sections 12 has been chosen to permit water to flow through at the required rate. The specific requirements for the flow rate will depend on the pump and the size of hose used.

The configuration of the weave means that water can pass through the gaps more quickly for gaps of a defined separation than can pass through a metal strainer of the type used in the prior art.

In a specific embodiment used, the woven sections are made of a three-rod upsetting weave. Because of the weave chosen, the plastics strands interlock and so cannot be picked apart. The plastics strands used in the weave are polypropylene extruded cane, advantageously a polypropylene extruded cane manufactured under the trade mark ROTALAK TIMPERLEY.

This material has been found to provide the necessary flexibility, resistance to water damage and ease of handling. The plastic canes may have a cross-sectional area of 3 x 2 mm.

The support rings 14, base 16 and perimeter ring 18 are made of the same wood which has a sufficient rigidity and resistance to water damage. A suitable wood is marine boat builders' plywood provided in accordance with British Standard Specification BS 1088. The plywood is coated with a suitable paint, preferably with at least three coatings - a primer, an undercoat and a top coat. A suitable paint for this application is Hamptons golden yellow polygloss paint which is currently used for hydrant markings and so both cost-effective and easily available. The support rings 14, base 16 and perimeter ring 18 provide both structural strength and a consistent constructional rigidity as well as some protection from external buffeting by objects in the water.

Figure 4 shows a plan view of the woven strainer of Figure 1 viewed from the open end with a perimeter ring 18. The warp of the woven sections 12 comprises a plurality of parallel metal bars 20 and parallel plastic rods 22. The metal bars 20 are typically made of zinc-coated steel or stainless steel and have a diameter of 4 mm. The plastic rods 22 are typically made of polypropylene plastic and may typically be of 3 mm diameter. Both the metal rods 20 and the plastic rods 22 extend the length of the woven strainer 10 and so pass through holes provided in the perimeter ring 18, the support rings 14 and the base 16. The metal rods provide an axial stable cylindrical column which enables the woven strainer 10 to withstand forces applied to the strainer 10.

Figures 5 and 6 show the attachment of the rods 20, 22 to the base 16 in greater detail. For the metal rods 20, a metal rod 20 is provided as a threaded bar and a nut 24 holds the metal rod 20 in position. For the plastic rods 22, a plastic rod is passed through a hole in the base 16 and then melted to form a bung 26 as shown. It will be appreciated that the hole in the base 16 needs to be shaped to accommodate the bung 26.

The rods 20, 22 may be attached to the perimeter ring 18 in a similar manner.

Figure 7 shows an exploded view of a connector 30 for use with a woven strainer 10. The connector 30 includes a round thread connection 32 for connection to a fire hose and an adaptor plate 34 for closing the open end of the woven strainer 10. The round threaded connection 32 has a female screw thread for connection to a fire hose. The round thread connection 32 and the adapter plate 34 may be formed as an integral unit.

Preferably, the connector and the adapter plate are joined by a floating ring on a collar to enable the connector to be tightened onto the hose without the need to rotate the woven strainer or the hose. The adapter plate 34 comprises a planar plate portion 36, an annular section 38 for joining the plate section 36 to the round threaded connection 32 and a depending side wall 40. Because the perimeter ring 18 of the woven strainer 10 is rigid, it is possible to seal the connector 30 to the woven strainer 10 with a sufficient hermeticity to allow water to be sucked through the strainer at the required rate. The side wall 40 is not an essential feature of the adapter plate 34 but does assist in locating the adapter plate 34 on the perimeter ring 18 and hence in making the final seal.

A suitable construction for a suction strainer/filter system comprises the connector 30 and three woven strainers of different diameters. The external woven strainer has an external diameter of 235 mm with the woven sections having a diameter of 195 mm. The end of the external woven strainer opposite the perimeter ring is closed with a rigid base. The intermediate woven strainer has an external diameter of 185 mm with woven sections of diameter 150 mm. The end of the intermediate woven strainer may end in a support ring to provide strength of construction or may be closed by a rigid base. The internal woven strainer has an external diameter of 140 mm with woven sections of diameter 110 mm. The end of the internal woven strainer opposite the perimeter ring is preferably closed with a rigid member or may simply end in a support ring to provide strength of construction. Typically a woven strainer for use with a hose of diameter 14 cm (5 inches) would have a height of about 38 cm while a woven strainer for use with a hose of diameter 11.4 cm (4 inches) would have a height of about 29.2 cm.

Because both the perimeter rings of the woven strainers and the adapter plate are made of relatively rigid materials, the two components may be easily attached together to provide the required seal. For the external woven strainer, the metal rods of the woven strainer may be sufficiently long to extend through holes in the plate portion 36 so that the connector 30 can be held in position on the external woven strainer using nuts threaded onto the metal rods of the external woven strainer. The internal woven strainer has a diameter such that it fits within the annular portion 38 of the adapter plate 34. The seal between the perimeter ring of the internal woven strainer and the annular portion 38 may be provided using a suitable washer. If both the external and internal woven strainers are held in position as described above, it may be sufficient for the intermediate woven strainer simply to be held in position by the location of the other components of the suction strainer. Alternatively, the face 36a of the plate portion 36 may have blind holes indented therein into which nuts attached to the metal rods of the internal woven strainer may be located. Those skilled in the art will easily be able to identify other means of attachment and location of the rigid adapter plate 34 and the rigid perimeter ring 18 to provide the required seals.

In use, it was found possible to pump water through the suction strainer described above at a rate exceeding present requirements (1996).

Figure 8 shows a low-level strainer/filter system 50 for use in pumping out water from a building or other enclosed area and space which has been flooded.

The low-level strainer/filter system 50 is formed of a connector 30 for connection to a hose and first and second woven strainers 10a, lOb. The general details of construction of the connector and woven strainers of Figure 8 are essentially the same as the connector 30 and woven strainer 10 described above. To facilitate removal of water from the flooded area when the water level is no more than, say, 30 cm (1 foot), the woven strainers l0a, lOb have a relatively short axial length and may, for example, be only 30 cm high with only two woven sections. The top section 52 of the first woven strainer l0a is covered with a metal cover to leave exposed a woven section 54 having a height of about 25 mm. The metal cover may be attached to the adapter plate by welding and to support rings in the first woven strainer l0a by suitable screws or other means of attachment.

Provision of the metal cover improves the suction of the system while the exposed woven section 54 reduces the risk of the low-level strainer/filter system being held to the floor by the suction. The second woven strainer lOb has a finer mesh than the first woven strainer l0a and is effective to filter water being removed from the flooded area. As shown, the second woven strainer lob is shorter than the first strainer l0a. This construction facilitates removal of water to a defined level, typically 2.54 cm (1 inch), being the difference in length between the woven strainers l0a, lob. Those skilled in the art will appreciate that, in a flooded building, once the water level has been reduced to such a depth, the remaining water will include a high proportion of solid residues which cannot easily be removed by pumping.

Figure 9 shows a schematic view of a woven strainer lOc for use inside a hose 60. The perimeter ring 62 of the woven strainer l0c is attached via a rubber seal 64 to a snaplock connector 66. The shoulder 66a of the snaplock connector 66, the seal 64 and the ring 62 extend across the internal diameter of the hose 60 and have a larger diameter than the diameter of the woven strainer lOc. Alternatively, a connection ring having the same diameter as the internal diameter of the hose 60 may be connected to the standard perimeter ring for a woven strainer.

Water flowing through the hose passes through and is filtered by the woven sections 68 of the woven strainer lOc.

Claims

CLAIMS:

1. A suction strainer/filter system for a hose comprising: a woven strainer through which liquid can flow; and a connector for sealingly connecting the woven strainer to a hose.

2. A suction strainer/filter system according to claim 1 in which the woven strainer has an open region with a first rigid member comprising a perimeter ring for making a seal with the connector.

3. A suction strainer/filter system according to claims 1 or 2 in which the woven strainer comprises at least one second rigid member comprising a support ring for providing structural support.

4. A suction strainer/filter system according to claim 3 in which the woven strainer comprises a plurality of second rigid members separated from each other for providing structural support.

5. A suction strainer/filter system according to any one of claims 1 to 4 in which the woven strainer comprises a closed region closed by a third rigid member.

6. A suction strainer/filter system according to any one of claims 2 to 5 in which the at least one rigid member is made of wood.

7. A suction strainer/filter system according to claim 6 in which the wood is coated by paint.

8. A suction strainer/filter system according to any one of the preceding claims in which the woven strainer has a warp formed by a plurality of parallel stakes.

9. A suction strainer/filter system according to claim 8 in which at least some of the parallel stakes are made of zinc plated metal or stainless steel.

10. A suction strainer/filter system according to claims 8 or 9 in which at least some of the parallel stakes are made of plastics material.

11. A suction strainer/filter system according to any one of claims 8 to 10 in which the woven strainer has a right circular cylindrical shape with an open end having a first rigid member and a closed end closed by a third rigid member.

12. A suction strainer/filter system according to any one of the preceding claims in which the woven strainer has a weft formed by a plastics material.

13. A suction strainer/filter system according to claim 12 in which the plastics material is polypropylene extruded cane.

14. A suction strainer/filter system according to claim 2 or any one of the preceding claims as dependent on claim 2 in which the connector comprises a round thread connection for connection to a hose and an adapter plate for closing the open end of the strainer.

15. A suction strainer/filter system according to claim 14 in which the adapter plate includes a side wall for overlapping the side of the rigid perimeter ring of a woven strainer.

16. A suction strainer/filter system according to claims 14 or 15 in which the adapter plate includes an annular portion for overlapping the side of the rigid perimeter ring of a woven strainer and sealed together using a washer of flexible material.

17. A suction strainer/filter system according to any one of claims 14 to 16 in which the adapter plate includes a plate portion at which a woven strainer is attached to the adapter plate.

18. A suction strainer/filter system according to any one of the preceding claims comprising a plurality of woven strainers as defined in any one of the preceding claims, at least one of the woven strainers having a closed region closed by a third rigid member as defined in claim 5.

19. A suction strainer/filter system according to claim 18 in which the plurality of woven strainers comprises an external woven strainer having said closed region and at least one internal woven strainer inside of the external woven strainer.

20. A suction strainer/filter system according to claim 18 in which the plurality of woven strainers comprises an external woven strainer having a second open region with a rigid support ring and an internal woven strainer inside of the external woven strainer, the internal woven strainer having said closed region.

21. A suction strainer/filter system according to claim 20 further comprising a metal cover depending from the connector to cover a portion of the weave of the woven strainer.

22. A suction strainer/filter system substantially as hereinbefore described with reference to any one of the accompanying drawings.