DE29822682U1 - hydrant - Google Patents

Description

17 December 1998

Heinz-Jürgen Pfitzner 67550 Worms

hydrant

The present innovation relates to a hydrant that serves as a tap for drawing water from municipal water networks. Such hydrants, usually designed as underground hydrants and directly connected to the underground water pipe, are used primarily by the fire brigade to draw water; however, they can also be used by private individuals using a standpipe.

Conventional hydrants, from which the present invention is based, are basically valves with a valve closing body, which can be pressed downwards onto its valve seat by means of an actuating spindle, whereby the actuating spindle engages in a nut arranged at the upper end of an extension tube referred to as a sleeve tube, and the valve closing member is rigidly connected to the lower end of the sleeve tube.

The known fire hydrants offer no security against sabotage. They are accessible to everyone and criminal elements could introduce pathogens or poison or the like into the municipal water network for extortion or other reasons, all that would be required is a readily available standpipe and a pump or other source of overpressure.

by means of which the dangerous substances could be introduced at a pressure exceeding the mains pressure.

The object of the present invention is to create a backflow-proof hydrant in which the risk of such sabotage attacks is largely minimized.

The solution to the problem is achieved by the features specified in the protection claims.

In the design according to the invention, the hydrant valve is supplemented by a check valve which is practically inaccessible to saboteurs and offers significantly greater safety.
15

The innovation is explained further below by describing an example of implementation based on the attached drawings. It shows:

Fig. 1 schematically shows a backflow-proof hydrant

in longitudinal section;

Fig. 2 shows the cross section A-A from Fig. 1; Fig. 3 shows the cross section B-B from Fig. 1.

The jacket pipe 1 of the hydrant is connected to the underground water pipe by means of a connection flange 2 at the lower end. At the upper end there is the bearing for the operating spindle 3 with its operating square 4 and next to this the bayonet connection sleeve 5 for a hose coupling or

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standpipe.

The actuating spindle 3 interacts with a spindle nut formed in the upper end of the sleeve tube 8. At the lower end of the sleeve tube 8, a valve closing body 6 is attached with shoe-like guide extensions that protrude downwards, as shown in Fig. 3, which releases the water flow when it is moved upwards. When closed, the jacket tube 1 can be emptied via a residual water outlet 7 in order to prevent freezing. In this respect, the hydrant corresponds to a known design.

Below the valve closing body 6, a check valve insert 10 is installed in the casing pipe 1 in the area of its connecting flange 2. This consists of a cylindrical housing with a diametrically running bearing web 12, to which an approximately semicircular check valve 14 is hinged on both sides, which in the closed position rests on a shoulder of the check valve cylinder housing 10 provided with an elastic seal. A torsion spring 16 surrounding the bearing web 12 presses with both arms on the check valves 14 and forces them to close. A spacer pin 18 protrudes from the surface of each check valve, which limits the opening movement of the flaps and sets the maximum opening position at an angle that ensures that the flaps close immediately in the event of any backflow.

When the hydrant described is in operation, the return

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The check valve's flaps 14 are opened without further ado by the water pressure prevailing in the network and the water is drawn off as with conventional hydrants. If the water flow stops, the check valves 14 return to the closed position under the effect of the torsion spring 16 and their own weight. If an attempt is made to introduce foreign substances into the pipe network by applying pressure that exceeds the network pressure, the check valves would be pressed even more firmly onto their seats and this would prevent this from happening.

It can be seen that this function and the inaccessibility of the check valve insert 10 make the hydrant practically safe from sabotage. 15

17 December 1998

LIST OF REFERENCE SYMBOLS

1 jacket pipe

2 Connection flange

3 Actuating spindle

4 Operating square

5 Connection sleeve

6 Valve closing body

7 Residual water drainage

8 Sleeve tube

10 Check valve insert; cylinder housing

12 Bearing bar

14 Check valve

16 torsion spring

18 Spacer pin

Claims (5)

17 December 1998 CLAIMS 1. Hydrant for water extraction from public water networks with a casing pipe (1) which has a flange (2) at the lower end for connection to the water network and in which a valve closing body (6) can be moved by means of an actuating spindle (3) and pressed onto its seat, characterized by a check valve (10) arranged in the casing tube (1) below the valve closing body (6). 15 2. Hydrant according to claim 1, characterized in that the check valve is designed in the form of a cylindrical housing insert that can be inserted into the casing pipe (1) from below. 3. Hydrant according to claim 1 or 2, characterized in that the check valve has two approximately semicircular check valves (14) hinged to a diametrically extending bearing web (12). 4. Hydrant according to claim 3, characterized by a two-armed torsion spring (16), each arm of which acts on a check valve (14) in the direction of closing. 5. Hydrant according to claim 3 or 4, characterized by spacer pins (18) projecting from the surfaces of the non-return valves (14).