GB2463687A

GB2463687A - Through bore fire hydrant

Info

Publication number: GB2463687A
Application number: GB0817278A
Authority: GB
Inventors: John Raymond Bartram
Original assignee: SIGMA COMMERCIAL PRODUCTS Ltd
Current assignee: SIGMA COMMERCIAL PRODUCTS Ltd
Priority date: 2008-09-22
Filing date: 2008-09-22
Publication date: 2010-03-24
Anticipated expiration: 2028-09-22
Also published as: GB2463687B; GB0817278D0

Abstract

A through bore fire hydrant incorporates a transversely movable sealing plate 15 moved through rotation of a main spindle 11. The plate sealing face is forced by mains pressure onto a hydrant body 1 seal face 34 creating a seal. Main spindle rotation causes a non-rotating nut 13 to rise on external spindle threads and the secondary spindle to extend downwardly on internal spindle threads of lower pitch (e.g. 5:1 outer:inner ratio) to force the seal plate off its seal face thereby equalising the pressure within the hydrant. The nut contains balls 16 running in axial then inclined grooves in cam member 14 so that as the nut rises there is no initial cam rotation followed by rotation which withdraws the plate. A method of isolating the hydrant from mains is also disclosed (Fig. 24) where a seal unit body (23) is attached to the closed hydrant outlet, the hydrant opened and a plug (28, 29) extended by threaded rod (24) to seal the hydrant inlet.

Description

I

TITLE

Through bore fire hydrant DESCRIPT!ON

Technical Field

The invention relates to a fire hydrant, which is normally situated below ground, usually in a street, and connected to a live water main. The hydrant contains a valve to regulate the flow and an outlet to which can be fitted a hose for fire fighting. The hydrant is also used by the water utilities for leak detection, chlorination, probe or camera insertion and temperature monitoring points, amongst other things.

Background of the invention

Historically, fire hydrants have been manufactured to an industry standard design that has an outlet port that is offset from the inlet port. The operating valve components are positioned in line with the inlet port and usually consist of a plug that seals against the pressure at the inlet port via a vertical spindle arrangement that is driven manually by a tee key.

This type of design does not offer particularly good flow performance as the water has to pass the plug in the open position and then flow onwards through a bend to the outlet. This configuration also makes access to the inlet port via the outlet port difficult due to the offset.

Although hydrants are manufactured to allow for the maintenance of 0 Ring seals operating on the main stem, other parts of the valve are not accessible without closure of the water main. In practice very little maintenance is conducted on hydrants for this reason and, for the most part, any leaking hydrant discovered, either by the fire brigade or a member of the public, is completely replaced. This involves the notification of residents and closure of the water main prior to accessing and replacing the faulty unit. This is a costly process that is also inconvenient to water consumers.

The aim of the invention is to overcome all of the above stated problems in a single product that will be lightweight and competitive in production.

It is desirable that the hydrant should not be capable of being opened or closed too rapidly, in order to avoid damage to the water main caused by a sudden change in pressure. A standard requirement is that at least five turns of the main spindle should be necessary to move the hydrant from its fully open to its fully closed position.

Summary of the invention

The invention provides a through bore hydrant as defined in claim 1.

The invention further provides a method of isolating a through bore hydrant from the pressure of a water main as defined in claim 17.

Preferred but non-essential features of the hydrant are defined in the dependent claims.

The invention provides for the alignment of the inlet and outlet ports of the hydrant to form a through bore. It is not essential that the ports be precisely concentric but it is preferred that there should exist a straight path between the inlet and the outlet for the easy introduction of probes etc, as well as improved flow of water. Conventionally, the through bore will be vertically orientated.

This is achieved by utilising an alternative sealing mechanism. The seal plate is moved transversely to the through bore (typically at right angles to it) by means of a rotating cam component, which is actuated by a main stem that is offset from the through bore. The seal plate is driven axially into the flow of the hydrant during closure whilst at the same time preferably allowing vertical, upward movement of the seal plate onto the seal face of the hydrant body. At full closure, this results in an improved seal between the hydrant body and seal plate that is enhanced by the pressurised water in the pipeline creating an on-seat sealing pressure. The outlet port allows for the concentric mounting of any desired outlet such as a BS750 compliant London Round Thread outlet that is used by the fire brigade for hose attachment.

When the hydrant is in the closed position this outlet can be removed in order to facilitate maintenance of the operating components of the hydrant should this be required. The outlet is removed and replaced with a plugging mechanism that seals onto the bore of the hydrant. This process effectively seals off the water pressure below the hydrant operating area. With the hydrant effectively sealed, the bonnet and internal components can either be repaired or be totally replaced by a new component assembly. This process can be completely carried out without any disruption to the mains supply.

It is also possible, using the same features, to fit the hydrant to a live main via an under-pressure tee and create a live hydrant by drilling into the main using special purpose drilling equipment. Once again, this process can be carried out without mains disruption.

In addition to the above, the concentric vertical alignment of the inlet and outlet ports also allows for the easy passage of specialist equipment into the main bore of the water main, such as swabs, CCTV, microphones and probes etc.

Description of the drawings

Figure 1 is an isometric view of the hydrant.

Figure 2 is an end view of the hydrant.

Figure 3 is a sectional side view of the hydrant through the main spindle in a fully closed position.

Figure 4 is an end view of the hydrant key components in the fully closed position.

Figure 5 is a sectional side view on line A-A of Figure 4 of the key operating components of the hydrant in the closed position.

Figure 6 is a detailed sectional side view of region B of Figure 5, showing key operating components of the hydrant in the closed position.

Figure 7 is a vertical side view of the hydrant.

Figure 8 is a sectional top view on line A-A of Figure 7 of the key components of the hydrant, in the closed position.

Figure 9 is a top view of the rotary cam mechanism showing the drive nut and hardened steel balls.

Figure 10 is a sectional side view on line A-A of Figure 9 of the rotary cam mechanism showing the position of the main spindle nut and hardened steel balls.

Figure 11 is an end view of the complete rotational cam assembly.

Figure 12 is a sectional view on line A-A of Figure 11 of the complete rotational cam assembly.

Figure 13 is an end view of the hydrant, identical to Figure 2.

Figure 14 is a sectional view on line A-A of Figure 13 through the main spindle showing the hydrant in the seal broken position.

Figure 15 is an end view of the hydrant, identical to Figures 2 and 13.

Figure 16 is a sectional view on line A-A of Figure 15 through the main spindle showing the hydrant in the fully open position.

Figure 17 is a vertical side view of the hydrant, identical to Figure 7.

Figure 18 is a sectional top view on line A-A of Figure 17 of the key components of the hydrant, in the fully open position.

Figure 19 is an end view of the hydrant, identical to Figures 2, 13 and 15.

Figure 20 is a sectional side view on line A-A of Figure 19 through the centre line of the hydrant showing the hydrant in the fully closed position with the sealing plate pivoted to seal on the bottom body seal face.

Figure 21 is an end view of the hydrant complete with bore sealing unit Figure 22 is a sectional side view on line A-A of Figure 21 through the centre line of the hydrant showing the hydrant in the fully closed position with the bore sealing unit in the open position.

Figure 23 is an end view of the hydrant complete with bore sealing unit, identical to Figure 21.

Figure 24 is a sectional side view through the centre line of the hydrant showing the hydrant in the fully open position with the bore sealing unit in the sealing position.

Detailed description of a preferred embodiment

One embodiment of the hydrant according to the invention, as shown in the drawings, has a ductile iron body 1 with an inlet flange for mounting onto a mating flange on the water main. The body is fitted with an outlet 3 that is bolted to an outlet flange that is concentrically aligned with the inlet mounting flange. As shown in the drawings, the outlet is a BS750 compliant London Round Thread outlet that may be used by the fire brigade for hose attachment. When not in use the outlet is protected by a cover 6, attached to the outlet by a cord 4.

A similarly fixed ductile iron bonnet 2 is bolted to the top face of the hydrant body 1 on the same horizontal plane as the outlet 3 (as shown in Figure 1).

A frost valve 5 in the hydrant body 1 allows water to drain away from the outlet port, which might otherwise lead to a damaging build-up of ice in the outlet during cold weather.

A sealing plate 15 slides within the hydrant body I in a plane that is perpendicular to the axis of the inlet and outlet 3. When the hydrant is fully closed, the sealing plate 15 blocks the passage between the inlet and the outlet 3 and a raised circular rim at one end of the sealing plate 15 is held against an upper sealing face 34 of the hydrant body 1 by the pressure from the water main (as shown in Figure 3) effectively creating an on-seat seal between the two faces.

The hydrant is actuated manually through cap top 7 that is fixed to the main spindle 11. The spindle 11 is constrained vertically within the bonnet 2 by cap top 7 and top bush 21. A main bronze nut 13 is threaded on an external, left hand thread of the main spindle 11. A moving spindle 12 is threaded on an internal, right hand thread in the bore of the main spindle 11, having a pitch about one fifth that of the external thread. For example, the pitch of the external thread may be 5mm and the pitch of the internal thread may be 1mm. Anti-clockwise rotation of the main spindle 11 through cap top 7 (as shown in Figure 3 with the hydrant in the fully closed position) causes the main nut 13 to rise vertically on the main spindle 11. At the same time, moving spindle l2moves vertically downwards.

Moving spindle 12 and main bronze nut 13 are prevented from rotation by nut retainer 17 and square nut 18, which are radially constrained within a long vertical slot 30 in sealing plate 15.

Sealing plate 15 is fixed in the vertical plane between the nut retainer 17 and the square nut 18 (as shown in Figure 4) although it can pivot about the centre point between nut retainer 17 and square nut 18 (as shown in Figures 5 and 6).

Sealing plate 15 can also move axially along the length of the long vertical slot 30 within it but is constrained from rotational motion by the internal wall of the body 1 of the hydrant (as shown in Figure 8). Sealing plate 15 contains a fitted plastic guide 20 along its square side that is guided along its stroke by a corresponding protrusion in hydrant body 1.

A rotary cam 14 has a hollow, generally cylindrical body, at one end of which there is a radially projecting leg carrying a drive pin 31 (as shown in Figures 9 and 10). On an inner surface of the cylindrical body there are formed two opposing cam channels 32. The rotary cam 14 is rotatably mounted between the hydrant body 1 and the bonnet 2 so that its cylindrical body surrounds the main spindle 11 and the main bronze nut 13, while its drive pin 31 engages with a short slot 33 in the sealing plate 15 that is transverse to the long slot 30.

The main bronze nut 13 contains, constrained within horizontally configured blind holes, two hardened steel balls 16 which are accurately positioned in the horizontal plane at a fixed point from the centreline of main spindle 11. The hardened steel balls 16 are free to rotate about the axis of the holes in the main bronze nut 13 but are, on assembly, also located within the corresponding radial profile of the respective cam channels 32 formed within rotary cam 14.

The cam form within rotary cam 14 includes at its bottom entry point a section that is vertically aligned with main spindle 11. This allows main bronze nut 13 with hardened steel balls 16 to enter through the bottom entry point. The cam mechanism that is made up from rotary cam 14, main bronze nut 13 and hardened steel balls 16 (as shown in Figure 10) allows for main bronze nut 13 to move in the vertical plane from the fully closed position with no immediate rotational effect on rotary cam 14. This equates to at least two full turns of main spindle 11. Therefore, as main bronze nut 13 rises during the rotary motion of main spindle 11, for about two full rotations there is no rotary effect on rotary cam 14.

As vertical movement of moving spindle 12 is unconstrained in the vertical plane, and it is pinned with pin 19 to square nut 18, it will proceed in a downward direction at the rate of 1/5 of the upward rate of the main bronze nut 13. Each turn of main spindle 11 results in a small downward movement of moving spindle 12 and all additional components attached to it, namely nut retainer 17, square nut 18 and sealing plate 15 (as shown in Figure 14).

This downward movement of moving spindle 12 is sufficient to force sealing plate downwards off the seal face 34 on body 1 thereby breaking the seal and relieving the pressure within body 1 that clamped the sealing plate 15 against the seal face 34. As the main bronze nut 13 continues to rise, after about two full rotations of main spindle lithe two hardened steel balls 16 will come into contact with curved sections of the cam channels 32 formed within rotary cam 14.

Further rotations of main spindle ii will therefore result in rotary cam 14 rotating about its axis as the two hardened steel balls are driven along the form of the cam. As the rotary cam 14 begins to rotate, the drive pin 31 on its extended leg, which is located in the short vertical slot within sealing plate 15, pulls the sealing plate 15 axially away from the main bore of the hydrant within body 1 (as shown in Figure 18).

After several rotations of the main spindle 11, main bronze nut 13 will reach the end of its upward stroke as it reaches a flange on the main spindle 11. At this point the moving spindle 12 will have travelled vertically downwards by one-fifth of that distance, carrying with it the nut retainer 17, square nut 18 and sealing plate 15. Also at this stage the rotary cam 14 will have rotated through approximately 1100 to the end of its stroke and will have pulled sealing plate 15 away from the bore of hydrant body 1 leaving a full clear through bore through which the water can pass (as shown in Figure 16).

Closure of the hydrant is achieved by rotating main spindle 11 through cap top 7 in a clockwise direction. Downward movement of the main bronze nut 13, containing hardened steel balls 16, which are located in the cam form within rotary cam 14, causes rotary cam 14 to rotate in a clockwise manner. The drive pin 31 on rotary cam 14, which is located within the small slot 33 in sealing plate 15, creates an axial movement of the sealing plate 15 and drives it towards the bore of hydrant body 1. As this motion progresses, moving spindle 12 is driven by the main spindle 11 in an upward direction, along with all attached components.

Sealing plate 15 is guided during this movement by a protrusion on hydrant body 1 that is in contact with plastic guide 20 that is attached to sealing plate 15 on its square side. This motion progresses until sealing plate 15 reaches the end of its stroke controlled by the rotation of main spindle 11. At this point sealing plate 15 will be located concentrically below the sealing face 34 on hydrant body 1. As the hardened steel balls situated within main bronze nut 13 reach the vertical portion of the cam form within rotary cam 14, the rotary motion ceases and is taken over by vertical movement only. The final turns of main spindle 11 take main bronze nut 13 to the end of its stroke and drive moving spindle 12, and all attached components, vertically until it collides with the bottom of main spindle 11. At this point, rotation of main spindle 11 ceases and the seating plate 15, which is still positioned concentrically to the main bore of hydrant body 1, has risen to make contact with the seal face 34 on hydrant body 1. The water pressure within the hydrant now forces the sealing plate 15 firmly onto the seal face 34 of hydrant body 1 creating a seal and cutting off flow to outlet 3. At this point the hydrant is closed (as shown in Figures 3 and 8).

Should the water pressure within the pipeline that the hydrant is fitted to fail for any reason, with the hydrant in the closed position, the seal will be broken between sealing plate 15 and the seal face 34 on hydrant body 1 As sealing plate 15 is capable of pivotal motion within the constraint created by nut retainer 17 and square nut 18, any zero pressure condition will cause sealing plate 15 to rotate about its axis at this point and drop onto an angled bottom seal face 35 on hydrant body 1. This creates a seal on the bottom face 35 that wilt prevent ingress of foreign matter into the main until pressure is restored (as shown in Figure 20). When mains pressure is restored, sealing plate 15 will be forced o upwards, pivoting on its axis, and the top seal on sealing plate 15 will be forced once again onto the top sealing face 34 of hydrant body 1 re-creating the seal.

An additional feature offered by the through bore hydrant invention is the ability to effectively isolate the hydrant and all of its operating components and seals from the water main to which it is attached.

This process is achieved by attaching a bore sealing unit (as shown in Figure 22) onto the outlet flange of a fully closed hydrant, in place of the hydrant outlet 3 and utilising the same fixing bolts.

With the bore sealing unit concentrically aligned with the main bore and bolted to the top flange of hydrant body 1, a seal is achieved between the top flange of hydrant body I and the bottom face of the bore sealing unit main body 23 by means of an 0 Ring. This leaves the hydrant as a completely sealed unit containing an equalised water pressure (as shown in Figure 22) and allows for the opening of the hydrant as previously explained.

With the hydrant fully open and sealing plate 15 moved away from the bore of hydrant body 1, the plug mechanism within the bore sealing unit main body 23 can be introduced. Rotation of rotating nut 26 and affixed threaded drive stem 24 moves the drive nut 25 and attached inner plug 29 and outer plug 28 in a downward direction (as shown in Figure 24).

This continues through its stroke until the increased diameter at the top of outer plug 28 comes into contact with the top face of the hydrant body 1. Continued rotation of rotating nut 26 now draws inner plug 29 in an upward direction causing the compression of bore seal 27 outwards onto the bottom bore of hydrant body 1, thereby giving a seal.

In this state the bottom bore of hydrant body 1 is completely sealed to prevent the passing of water from the main. This then allows the bolts holding the hydrant bonnet 2 to be removed allowing the bonnet 2 and all attached components to be completely removed from hydrant body 1. Work to repair any defective seals or components can now be carried out away from the hydrant or the whole bonnet assembly can be completely replaced with a new unit. Once re-assembled, the hydrant becomes live again and the previous operations can be reversed to retract the sealing mechanism of the bore sealing unit. When fully retracted the hydrant can be closed as previously described and the bore sealing unit can be removed and replaced by the original outlet. The hydrant is at this point fit for normal use.

A similar operation allows the live drilling of the water main, under pressure, when first installing the hydrant. The hydrant can be attached to an under pressure tee fixed and sealed onto the mains pipe work. Instead of a simple bore sealing unit as described above, the hydrant facilitates access to the mains pipe for a special purpose drilling machine that can both seal against the bore and drill a hole through the pipe. With the drilling machine retracted, the hydrant can be closed as previously described, leaving a live hydrant for ongoing use.

The attachment of various other components/fixtures to the top flange of hydrant body I allows access to the water main by the water utility or other authorised personnel for purposes such as sampling, while devices such as sensors and cameras can be easily introduced into the main via the straight through bore.

Claims

CLAIMS1. A through bore hydrant comprising: a hydrant body (1) having an inlet port, an outlet port (3) that is generally aligned with the inlet port to define a through bore, and a first seal face around the through bore between the inlet and outlet ports; a sealing plate (15) that moves in a direction transverse to the through bore between an open position in which it does not obstruct the through bore and a closed position in which it can engage the seal face; and a main spindle (11) connected to the sealing plate (15) via a cam (14) such that rotation of the main spindle (11) causes the sealing plate (15) to move between the open and closed positions.
2. A through bore hydrant according to claim 1, wherein the connection between the main spindle (11) and the sealing plate (15) is such that more than a full turn of the main spindle (11) is required to move the sealing plate (15) from its open position to its closed position.
3. A through bore hydrant according to claim 2, wherein at least five full turns of the main spindle (11) are required to move the sealing plate (15) from its open position to its closed position.
4. A through bore hydrant according to any preceding claim, wherein the axis of the main spindle (11) is generally parallel to the through bore.
5. A through bore hydrant according to claim 4, wherein rotation of the main spindle (11) further causes a movement of the sealing plate (15) parallel to the axis of the main spindle (11).
6. A through bore hydrant according to claim 5, wherein, when the sealing plate (15) is in its closed position and engages the seal face, rotation of the main spindle (11) initially causes movement of the sealing plate (15) only parallel to the axis of the main spindle (11) and not transversely to the through bore.
7. A through bore hydrant according to claim 6, wherein at least the first two full turns of the main spindle (11) cause movement the sealing plate (15) only parallel to the axis of the main spindle (11).
8. A through bore hydrant according to any of claims 5 to 7, wherein a moving spindle (12) is engaged via a screw thread with the main spindle (11) and is prevented from rotating, whereby rotation of the main spindle (11) causes linear movement of the moving spindle (12), which drives the movement of the sealing plate (15) parallel to the axis of the main spindle (11).
9. A through bore hydrant according to any preceding claim, wherein a nut (13) is engaged via a screw thread with the main spindle (11) and is prevented from rotating, whereby rotation of the main spindle (11) causes linear movement of the nut (13), which in turn drives rotation of the cam (14) to move the sealing plate (15) transversely to the through bore.
10. A through bore hydrant according to claim 9, wherein: the cam (14) has a cylindrical wall surrounding the nut (13); at least one cam follower (16) on the nut (13) engages with a respective channel (32) in the cylindrical wall of the cam(14); and the cam channel (32) has a generally helical portion by which linear movement of the nut (13) is converted to rotational movement of the cam (14).
11. A through bore hydrant according to claim 9, wherein: the cam channel (32) further has an axial portion by which linear movement of the nut (13) is not converted to rotational movement of the cam (14).
12. A through bore hydrant according to any preceding claim, wherein a drive pin (31) on the cam (14) engages a slot (33) in the sealing plate (15) to convert rotation of the cam (14) to linear motion of the sealing plate (15) in a direction transverse to the through bore.
13. A through bore hydrant according to any preceding claim, wherein the sealing plate (15) is urged against the first seal face by mains pressure when the hydrant is closed.
14. A through bore hydrant according to claim 13, wherein: the first seal face is above the sealing plate (15); the hydrant body (1) has a second seal face around the through bore below the sealing plate (15); and the sealing plate (15) is pivotally mounted such that, in the event of a loss of mains pressure when the hydrant is closed, the sealing plate (15) may pivot downwards to rest against the second seal face.
15. A through bore hydrant according to any preceding claim, further including a bore sealing unit that comprises: a sealing unit body (23) that can be fixed over the outlet of the hydrant body (1) to seal the outlet; and a plug (28,29) that can be moved into the through bore when the sealing plate (15)is in its open position to seal the inlet of the hydrant.
16. A through bore hydrant according to claim 15, wherein the plug comprises first and second plug parts (28,29) trapping a resilient seal (27) between them; and wherein the first and second plug parts (28,29) can be moved relative to one another to deform the resilient seal into sealing engagement with the wall of the inlet of the hydrant.
17. A method of isolating a through bore hydrant from the pressure of a water main, comprising the steps of: inserting a sealing plate (15) of the hydrant between an inlet and an outlet of the through bore to seal the bore; fixing a sealing unit (23) over the outlet of the hydrant to seal the outlet; retracting the sealing plate (15) to open the bore; and extending a plug (28,29) of the sealing unit through the bore to seal the inlet of the hydrant.
18. A through bore hydrant substantially as described herein with reference to Figures ito 20 or Figures 21 to 24 of the drawings.