GB2129064A - Hydrants - Google Patents

Abstract

A hydrant (0) for use in the street has a main shaft (20) which can be rotated manually and a follower shaft (30) screwed round the main shaft and upwardly movable upon rotation of the main shaft. The follower shaft (20) is integral with a plug member (40) at its lower end which can selectively block and unblock a mains water inlet. An air-venting member (44) is movable into and out of a through bore in the plug member (40) for exhausting air from the interior of the hydrant upon water inflow to avoid interruption of the flow by air blockages and for allowing air to pass into the hydrant upon cessation of the inflow. The hydrant (0) has an outlet (60) at each side and the level of the bottom of each outlet is substantially coincident with the level of the top of the mains water inlet so that water can be allowed to drain away easily to avoid water collecting in the interior of the hydrant. <IMAGE>

Description

SPECIFICATION Hydrants This invention relates to hydrants, in particular street fire hydrants. In some countries, the domestic water system, the public water system and the industrial water system are not installed separately. The purpose of a fire hydrant is not only for putting out a fire, but also for streetcleaning and for irrigating parks. The fire hydrant is also needed by water works for draining water and exhausting the air in the water system. In a conventional fire hydrant, the water pipe is filled with air when the water supply is interrupted.

When the water returns, the air in the pipe causes the water to flow slowly and as a result, the.water will be unable to reach the place where it is needed quickly. After a build-up of air the fire hydrant must be adjusted to exhaust the air. This would waste manpower and time.

Moreover, a serious problem in a known fire hydrant is the position of the water valve, which is located at the bottom of hydrant. After draining water, there will be several litres of water remaining inside, which after a number of days deteriorates and harbours bacteria and especially in warm countries, insects. The hydrant may be cleaned by special personnel but there will be a heavy labour cost. In the event of a water interruption or shortage, the water remaining in the hydrant may flow back into the pipe because of the pressure in the hydrant being insufficient and a cross-connection phenomenon may result, which is considered a serious problem.

It is accordingly a principal object of this invention to obviate the abovementioned drawbacks.

According to one aspect of the invention, propose a hydrant including a mains water inlet and a movable plug member for selectively blocking and unblocking the mains water inlet and a movable air-venting member for exhausting air from the interior of the hydrant upon inflow of water via the mains water inlet and allowing air to pass into the hydrant upon cessation of water inflow.

According to another aspect of this invention, I propose a hydrant including a mains water inlet and a movable plug member for selectively blocking and unblocking the mains water inlet and one or more water outlets in the side of the hydrant wherein the level of the top of the mains water inlet is substantially coincident with the level of the bottom of the or each side outlet so that residual water can drain away.

In the fire hydrant of this invention, the main shaft is rotated by a handle and simultaneously, a plug member is moved upwards so as to allow the water to drain out of a water outlet at each side of the body. This is achieved because the lower end of the main shaft is externally threaded and a cooperative follower shaft is correspondingly internally threaded, so that it is upwardly movable around the main shaft. The plug and the follower shaft are fixed together with screws; under the bottom of the plug, there is packing and a pad around the edge for softening the contact with the plug seat. In the centre of the plug there is a hole which is in communication with air outlet holes.

A spring housing is fixed on the top of the plug with screws. A compression spring and an airventing member cover are installed inside the spring housing and the top of the air-venting member is covered with the cover. The air-venting member may be moved up and down to exhaust and allow in air, employing the restoring force of the spring.

Yet another feature of the present invention is that the water outlet cover is closed from outside; miscellaneous matter outside the pipe is thus not liable to enter into the pipe. Residual water will drain away quickly after use to stop water collecting in the inside of the hydrant and avoid problems, such as encouraging insects.

An embodiment of the invention is described by way of example, with reference to the drawings, in which: Figure 1 is a sectional view of a fire hydrant according to the present invention; Figure 2 is a sectional view of the hydrant shown in Figure 1 with the plug open.

A fire hydrant has a body (0), of which the top has a top lid (1), and under the top lid (1), there is a hydrant lid (2). Under the hydrant lid, a top plate (3) is furnished and is fixed to a top frame (5) together with the hydrant lid (2) by means of a screw (4). Between the top plate (3) and the top frame (5), there is a pad (6). Under the top lid (1), there is a handle (10).

Inner packing (12) and a lower collar (13) are installed around a centrally disposed stem (11) located above and integral with a main shaft (20).

There is also a rotary pin (15) penetrating through the stem (11). At the lower end of the main shaft (20), external threads are furnished; inside the main shaft (20), a hollow cylindrical portion (22) is furnished. Around the lower portion of the main shaft (20), a hollow follower shaft (30) is installed.

The internal threads (31) of the follower shaft (30) couple with the externally threaded edge (21).

The bottom end of the follower shaft (30) is fixed to a plug member (40) by means of screws (32). Under the bottom of the plug (40), there is packing (41) and a pad (42). In the centre of the plug (40), there is a plug hole (43) for housing an air-venting member (44). A spring cover (50) is fixed over the plug valve (40) by means of screws (59). Inside the spring cover (50), a compression spring (51) and a plug cover (52) are furnished.

The top of the air-venting member (44) is housed inside the plug cover (52). Under the bottom of the air-venting member (44) there is a buoyancy plate (58). At both sides of the spring cover (50) and on the top of the plug valve (40), there are a number of air-venting holes (53) and (54) leading from the plug hole 43. At both sides of the body (0), there are chains (55) which link water outlet covers (56) to the body (0).

To obtain water, the top lid (1) is opened; the handle (10) is turned by hand to rotate the main shaft (20). As the internal threads (31) on the follower shaft (30) are coupled with the external threads (21), the follower shaft (30) will then be moved upwards, so the plug (40) will open the water outlet cover (56) and the water will then be able to flow out of the hydrant.

Referring to Figure 2, there is shown a hydrant with the maximum upward displacement of the follower shaft (30). The upward displacement is limited by the spring cover (50) reaching the inner portion of the hollow cylindrical portion (22). Upon turning the handle (10) in the reverse direction, the follower shaft (30) will move back downwards until the pad (42) under the plug is in close contact with the inlet seat. The water pipe is then closed by the plug (40). When water is not flowing in the pipe, the air-venting member will drop downwards out of the cylindrical portion (22) as a result of the reaction force of the spring (51). Upon the pipe being filled with water, the air in the pipe will be exhausted through the air-venting holes (53) and (54) of the hollow cylinder (22).

Therefore, on closure of the plug the air valve will move downwards and there will be substantially no residual water remaining in the hydrant and the excess air and resultant insufficient water pressure problem will also be substantially eliminated.

Further, the problems of deteriorating state, bad smelling water and the miscellaneous matters in the hydrant will also be substantially obviated.

Claims (10)

1. A hdyrant including a mains water inlet and a movable plug member for selectively blocking and unblocking the mains water inlet and a movable air-venting member for exhausting air from the interior of the hydrant upon inflow of water via the mains water inlet and allowing air to pass into the hydrant upon cessation of water inflow.

2. A hydrant according to claim 1 , further including a main shaft which is rotatable, and a follower shaft which is longitudinally movable upon rotation of the main shaft and which is integral with the plug member.

3. A hydrant according to claim 2, wherein the air-venting member is movable in a through bore in the plug member against a spring from a first position allowing passage of air through the bore to a second position preventing passage of air through the bore whereby upon release of water pressure against the air-venting member it is returnable from the second position to the first position.

4. A hydrant according to claim 3, wherein the spring is housed within a cover attached to the plug member and the cover includes one or more air outlet holes.

5. A hydrant according to any one of claims 2 to 4, wherein the main shaft is rotatable manually by means of an externally exposable handle.

6. A hydrant according to any one of claims 2 to 5, wherein the follower shaft has internal threads which are cooperable with matching external threads on the main shaft.

7. A hydrant according to any preceding claim, wherein the plug member is padded for cushioning against the seat of the mains water inlet.

8. A hydrant according to any preceding claim, having two mutually opposite outlets in the sides of the hydrant.

9. A hydrant including a mains water inlet and a movable plug member for selectively blocking and unblocking the mains water inlet and one or more water outlets in the side of the hydrant wherein the level of the top of the mains water inlet is substantially coincident with the level of the bottom of the or each side outlet so that residual water can drain away.

10. A hydrant constructed and arranged substantially as herein described with reference to either of the drawings.