Backflow-protected hydrant

Abstract

Backflow-protected hydrant (1) for connection to a liquid supply line comprising a main valve (7) and a backflow preventer (5) positioned upstream of the hydrant (1) in the outflow direction to prevent backflow of contaminants into the liquid supply line, wherein the backflow preventer (5) comprises a backflow valve body (17) movable along a locking axis between a closed position and an open position and a backflow valve seat (18) corresponding to the backflow valve body (17), and the main valve (7) comprises a main valve body (11) movable from a closed position to an open position against the flow direction of the hydrant (1) and a main valve seat (12) corresponding to the main valve body (11), characterized in that the backflow valve seat (18) is designed to be movable along the locking axis.

Description

[0001] The invention relates to a backflow-protected hydrant according to the preamble of claim 1.

[0002] Fire hydrants are widely used to draw water from a water supply line. The hydrant fitting typically includes a main valve to regulate the flow of water. However, in various applications, such as firefighting water extraction by the fire department, there is a risk that when the main valve is opened, debris like stones or contaminated water can bypass the valve and enter the water supply line, thus contaminating the water distribution system and causing unwanted pollution. Since these hydrants are usually connected to the drinking water supply line, contamination must be avoided at all costs.

[0003] From DD 252 408 A1, a hydrant with a protective valve is known, wherein the protective valve is designed to prevent the ingress of a foreign object located in the hydrant into the main line of a liquid supply line. For this purpose, a backflow preventer is provided upstream of the main valve in the outflow direction to prevent the backflow of foreign objects such as stones. The backflow preventer consists of a cup-shaped backflow valve body, which is displaceable by means of a spring along a locking axis between a closed position and an open position, and a corresponding bushing-like backflow valve seat. The cup-shaped backflow valve body points with its free edge in the outflow direction of the hydrant and, in particular, vertically upwards, so that it forms a collection container for the stones.To ensure that stones are reliably collected in the closed position, the socket-shaped check valve seat is designed so that the check valve body is completely surrounded by the check valve seat in the closed position. In the closed position of the main valve and the check valve, stones can thus collect in the cup-shaped check valve body and are held there, preventing them from entering the water distribution system when the main valve and check valve are subsequently opened.

[0004] While such a protective valve largely prevents the ingress of foreign objects like stones into the liquid supply line, it cannot reliably prevent the ingress of contaminated water. In particular, if the main valve is open and the external system pressure above the main valve is higher than the network pressure of the supply line, contaminated water can flow back against the flow direction of the hydrant through the backflow preventer into the water distribution system.

[0005] From DE 30 31 520 A1, a backflow-protected hydrant for connection to a liquid supply line is known. The hydrant comprises a main valve and a backflow preventer located upstream of the hydrant in the outflow direction to prevent the backflow of contaminants into the liquid supply line. The backflow preventer includes a backflow valve body that is movable along a locking axis between a closed position and an open position, and a backflow valve seat corresponding to the backflow valve body. The main valve also includes a main valve body that is movable from a closed position to an open position in the opposite direction to the flow direction of the hydrant, and a main valve seat corresponding to the main valve body.However, when the main valve body moves against the flow direction into the open position, leaks can occur at the backflow valve seat due to the compression volume above the backflow valve body, resulting in the passage of contaminated water into the liquid supply line.

[0006] Further backflow-protected hydrants are known from DE 202 01 884 U1, EP 1 010 824 A1 and DE 41 19 105 A1.

[0007] The object of the invention is therefore to enable a hydrant with a backflow preventer for a liquid supply line, by which a reliable backflow of contaminated water into the liquid supply line is ensured in every operating phase, in particular when the main valve of the hydrant is opened.

[0008] This problem is solved by a backflow-protected hydrant with the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

[0009] The backflow-protected hydrant according to the invention is characterized by the fact that the backflow valve seat is designed to be movable along the locking axis. During the opening movement of the main valve body against the outflow direction and in the direction of the backflow preventer, the hydrostatic pressure of the essentially incompressible fluid presses the backflow valve body against the backflow valve seat, and as a compensating movement, both the backflow valve body and the backflow valve seat move along the locking axis. Throughout the entire opening movement of the main valve, the pressure of the backflow valve body against the backflow valve seat ensures reliable contact between the corresponding sealing surfaces on the backflow preventer, thus achieving a particularly good sealing effect of the backflow preventer.

[0010] In an advantageous embodiment, the check valve seat can be designed as a flexible annular disc diaphragm with a radially outer mounting area and a radially inner sealing area for sealing contact with the check valve body. Such an annular disc diaphragm has a circular, flat shape with a low height compared to its planar extent and is preferably made of an elastic material such as rubber. This ensures that the radially inner sealing area of ​​the annular disc diaphragm is movable along the sealing axis relative to the radially outer mounting area, while the radially outer area provides a secure and tight seal for the annular disc diaphragm. Such an annular disc diaphragm is easy to manufacture and therefore particularly cost-effective.

[0011] Preferably, the radially inner sealing area on the side facing the check valve body can have a sealing bead for sealing contact with the check valve body. This sealing bead can, for example, have a contact area that is at least partially rounded, in particular circular, for sealing contact with the check valve body. This sealing bead ensures secure contact and thus a reliable sealing effect of the check valve, especially when the relative angular position of the sealing bead to the check valve body changes during their movement in the same direction as the main valve body opens.

[0012] In an advantageous embodiment, the check valve body is designed to move together with the check valve seat in the closed position. In the closed position, which is characterized by the mutual sealing contact of the check valve body and the check valve seat, the check valve body can thus move together with the check valve seat in the direction of the locking axis to allow a compensating movement to the opening movement of the main valve body.

[0013] To support the backflow valve seat, a sealing plate can be provided downstream of the backflow valve seat in the outflow direction of the hydrant. The sealing plate can also have a sealing chamfer for contact with an annular bead arranged on the backflow valve body. Preferably, the backflow valve seat, which is movable along the sealing axis, is positioned between contact with the sealing plate and a position deflected by the backflow valve body against the flow direction of the hydrant, in which the sealing surface of the backflow valve body rests against the sealing chamfer of the sealing plate.

[0014] To ensure safe opening of the main valve, the non-return valve seat can preferably be movable along the locking axis just far enough to compensate for a reduction in volume of the space enclosed between the main valve and the non-return valve due to movement of the main valve from the closed position to the open position by a movement of the non-return valve body and non-return valve seat in the same direction along the locking axis.

[0015] In an advantageous embodiment, the non-return valve body is a float with a density greater than 1.3 kg / dm³. 3 is designed and the backflow-protected hydrant is arranged in such a way that the float is acted upon by its weight force in the direction of the backflow valve seat.

[0016] Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings. These show: Fig. 1 a sectional view of a backflow-protected hydrant with a main valve and a backflow preventer; Fig. 2 a detailed view of the section view from Fig. 1, where the half-section shows the backflow preventer in two different closing positions: Fig. 3 a sectional view of the backflow-protected hydrant of Fig. 1, in which the main valve is closed and the backflow preventer is in a first closed position; Fig. 4 a sectional view of the backflow-protected hydrant of Fig. 1, in which the main valve is moved into an open position and the backflow preventer is in a second closed position; Fig. 5 a sectional view of the backflow-protected hydrant of Fig. 1, in which the main valve and the backflow preventer are open; Fig. 6 a sectional view of the backflow-protected hydrant of Fig. 1, in which the main valve is open and the backflow preventer is in the first and second closed positions in a half-section view; Fig. 7 a cross-sectional view of a single backflow preventer made of Fig. 1; Fig. 8 a cross-sectional view of a fire hydrant of Fig. 1, which without the backflow preventer in Fig. 7 was assembled.

[0017] In Fig. Figure 1 shows a longitudinal section of a backflow-protected hydrant 1. The hydrant 1 has a housing consisting of three parts. On the underside, a connection piece 2 is shown in two different versions: one straight and one bent at 90 degrees. Both versions have a connection flange 3 for connecting the hydrant 1 to a fluid supply line, such as the drinking water network. At the end opposite the connection flange 3, the connection piece 2 is connected to a center section 4, in which a backflow preventer 5 is located. Finally, an outlet piece 6 with a main valve 7 is provided on the top of the center section 4. Seals 8 are provided between each of the three housing parts to seal the housing.The middle piece 4 is firmly clamped between the connecting piece 2 and the outlet piece 6 by means of screws 9 with corresponding nuts 10.

[0018] The main valve 7 can be used to start and stop the flow of fluid through the hydrant 1. In the illustrated embodiment, the flow direction is vertical, from bottom to top, i.e., starting at the connection piece 2, through the middle piece 4, and into the outlet piece 6. The main valve 7 comprises a main valve body 11, which can be moved from a closed position to an open position in the opposite direction to the flow direction of the hydrant 1, and a main valve seat 12 corresponding to the main valve body 11. The main valve body 11 is designed as a rubber-coated shut-off cone with a conical, rotationally symmetrical cross-section, the tapered conical cross-section being oriented in the flow direction of the hydrant.The base 13 of the conical main valve body 11 is concavely curved, so that the fluid pressure acting there presses a substantially cylindrical outer sealing surface 14, which surrounds the concave base 13, radially outwards against a cylindrical inner sealing surface 15 of the main valve seat 12, resulting in a particularly good seal. To increase the elasticity of the conical main valve body 11, it is designed with hollow walls, thus facilitating the radial outwards pressing of the cylindrical outer sealing surface 14.

[0019] The main valve 7 is opened by moving the main valve body 11 against the flow direction of the hydrant, i.e., vertically downwards in the illustration. Due to the concave curvature of the base 13 of the conical main valve body 11, the radially outward contact pressure of the cylindrical outer sealing surface 14 against the cylindrical inner sealing surface 15 of the main valve seat 12 is maintained until the main valve body 11 emerges from the cylindrical inner sealing surface 15 of the main valve seat 12 and the sealing surfaces 14 and 15 are no longer in contact. From this point on, the main valve 7 is open and fluid can flow through the main valve 7 in the flow direction of the hydrant 1. During the closing process of the main valve 7, the main valve body 11 is moved in the flow direction of the hydrant 1 until the sealing surfaces 14 and 15 come into contact again.To center and gently insert the outer sealing surface 14 into the cylindrical inner sealing surface 15 of the main valve seat 12 and to slightly preload it radially inwards, the cylindrical inner sealing surface has an insertion chamfer 16. A significant advantage of the main valve body closing in the direction of flow of the hydrant 1 is that the closing movement is assisted by the applied fluid pressure, i.e., both the hydrostatic and hydrodynamic fluid pressure, making this main valve 7 particularly easy and reliable to operate from the open position to the closed position. When the main valve 7 is operated from the closed position to the open position against the actual flow direction of the hydrant 1, only the lower hydrostatic back pressure of the fluid in the central piece 4 is relevant.to overcome the connecting piece 2, which corresponds to the liquid pressure in the liquid supply line, since the liquid is still at rest during this opening movement of the main valve 7.

[0020] The backflow preventer 5 is located within the central section 4, i.e., upstream of the main valve 7 in the flow direction of the hydrant 1, and comprises a backflow valve body 17 that is freely displaceable between a closed and an open position along a locking axis corresponding to its longitudinal axis, and a backflow valve seat 18 corresponding to the backflow valve body 17. The backflow valve body 17 has a cylindrical guide section 19, which is longitudinally movably mounted in a cylindrical bushing 21 that is supported centrally in the central section 4 by means of webs 20. The cylindrical bushing 21 is oriented in the central section 4 such that the backflow valve body 17 can move along the flow direction of the hydrant 1.Due to the vertical orientation of the hydrant 1 shown, the backflow valve body 17 is also movable in a vertical direction, so that it is pushed downwards in a vertical direction by its weight.

[0021] The non-return valve seat 18 is located on the underside of the center piece 4 at the transition to the connector 2 and is formed by a flexible annular disc diaphragm 22, which has a radially outer mounting area 23 and a radially inner sealing area 24. The radially outer mounting area 23 is clamped between the center piece 4 and the connector 2 and is therefore fixed. The radially inner sealing area 24 is movable relative to the radially outer sealing area 23 in the direction of the longitudinal axis of the non-return valve body 17, which is achieved by making the non-return valve seat 18 from a flexible material such as rubber.

[0022] In the direction of flow of the hydrant 1 seen after the backflow valve seat 18, a sealing plate 25 is provided which limits the movement of the radially inner sealing area 24 of the backflow valve seat 18 in the direction of flow, i.e. vertically upwards in the illustration shown.

[0023] In Fig. 2 is the middle section 4 of the backflow-protected hydrant of Fig. Figure 1 shows a detailed view of the backflow preventer 5. Two different closing positions of the backflow preventer 5 are depicted in a half-section. In the left half-section, the backflow valve body 17, together with the radially inner sealing area 24 of the backflow valve seat 18, is in an upper closing position, whereas in the right half-section, the backflow valve body 17, together with the radially inner sealing area 24, is in a lower closing position. Both closing positions are characterized by the fact that the radially inner sealing area 24 is in a sealing position against the backflow valve body 17.

[0024] In the upper closed position, the radially inner sealing area 24 also rests against the sealing plate 25. If the non-return valve body 17 is then moved vertically downwards against the flow direction of the hydrant 1, it pushes the radially inner sealing area 24 in the same direction, so that the non-return valve body 17 and the radially inner sealing area 24 move together until the lower closed position shown in the right half-section is reached. In this lower closed position, the radially inner sealing area 24 continues to seal against the non-return valve body 17, but not against the sealing plate 25. An annular bead 26 is formed on the non-return valve body 17, which runs ring-shaped around the outside of the non-return valve body 17 and, in the lower closed position, comes into sealing contact with a sealing chamfer 27 arranged on the sealing plate 25.This arrangement of the ring bead 26 on the sealing slope 27 forms, in addition to providing an additional seal for the backflow preventer 5, a vertical stop for the backflow valve body, which limits its movement against the flow direction of the hydrant 1, i.e. in a vertical downward direction.

[0025] The radially inner sealing area 24 comprises a sealing bead 28, which has a rounded, in particular arc-shaped, sealing surface for contact with a similarly rounded sealing surface on the check valve body 17. Due to the rounded sealing surfaces, despite the difference in pressure between the surfaces, a seal can be maintained. Fig. The two different closing positions shown result in different relative angular positions of the radially inner sealing area 24 to the backflow valve body 17, ensuring a secure mutual contact and thus a reliable linear seal.

[0026] In the Fig. 3, Fig. 4, Fig. 5 to Fig. 6 is the backflow-protected hydrant 1 from Fig. 1 shown in different functional positions. Fig. In position 3, the main valve 7 is closed, meaning the main valve body 11 is located in the main valve seat 12 and the cylindrical outer sealing surface 14 is in sealing contact with the cylindrical inner sealing surface 15. Due to its weight, the non-return valve body 17 is pressed downwards against the radially inner sealing area 24 of the non-return valve seat 18. The non-return valve seat 18 is designed such that the radially inner sealing area 24 does not move despite the weight of the non-return valve body 17. Thus, the non-return valve 5 is in the upper closed position.

[0027] In Fig. Figure 4 shows one stage of the opening process of the backflow-protected hydrant 1. For this, the main valve body 11 of the main valve 7 is opened against the flow direction of the hydrant from the Fig. The main valve body 11 moves vertically downwards from the closed position shown in Figure 3 to an open position. This movement of the main valve body 11 forces the fluid located in the central section 4 between the main valve 7 and the non-return valve 5 downwards, as the fluid is incompressible. To provide a corresponding compensation volume for the fluid forced downwards and thus enable the opening movement of the main valve body 11, the non-return valve 5 moves from the upper closed position to the lower closed position shown.In both the upper and lower closed positions, and between the two closed positions, the radially inner sealing area 24 of the non-return valve seat 18 seals against the non-return valve body 17, so that during this opening process of the main valve 7 no liquid from the center piece, which may contain contaminants, can enter vertically downwards through the non-return valve 5 into a liquid supply line connected to the connection flange 3 of the connection piece 2.The position of the annular bead 26 on the non-return valve body 17 is chosen such that the additional volume in the central piece 4, which is released from the upper closed position to the lower closed position by the joint movement of the non-return valve body 17 and the radially inner sealing area 24 of the non-return valve seat 18, is at least as large as the volume of fluid which is displaced vertically downwards towards the non-return valve 5 by the opening movement of the main valve body 11.

[0028] In Fig. Figure 5 shows the main valve 7 in the open position, in which the cylindrical outer sealing surface 14 is out of contact with the cylindrical inner sealing surface 15, allowing fluid to flow vertically upwards through the main valve 7 in the direction of flow from the hydrant 1. Once the main valve 7 is open, the higher fluid pressure in the fluid supply line forces fluid upwards against the non-return valve 5, whereupon the non-return valve body 17 is lifted by the fluid flow into the open position shown. In this upper open position, the non-return valve body 17 rests against the main valve body 11, particularly the concave base 13, and together with the main valve body 11 forms a flow-optimized overall geometry to achieve the required flow rates.This means that both the backflow preventer 5 and the main valve 7 are open, and fluid can flow from the fluid supply line through the connector 2, the middle piece 4, and the outlet piece 6.

[0029] In Fig. Figure 6 shows the operating state in which the main valve 7 is still open, but due to insufficient pressure in the fluid supply line, the fluid does not flow in sufficient quantity around the check valve body 17 in the flow direction of the hydrant 1. As a result, the check valve body sinks down onto the check valve seat 18 under its own weight and, in the upper closed position, comes into sealing contact with the sealing bead 28 of the radially inner sealing area 24 of the check valve seat 18. To achieve a weight-driven sinking of the check valve body 17 that occurs faster than a backflow of the fluid, the check valve body 17 has a specific density greater than 1.3 kg / dm³. 3The non-return valve body 17 can be designed either with a rubber-lined aluminum hollow core, with a solid plastic body of suitable specific gravity, or with a one- or multi-part hollow plastic body with an internal metal core to achieve the specified specific density. This reliably prevents backflow of potentially contaminated liquid against the flow direction of the hydrant 1 past the non-return valve 5, especially even at low back pressure.

[0030] In the event of a significant drop in fluid pressure in the fluid supply line, which can occur, for example, due to a defect, the non-return valve body 17, together with the radially inner sealing area 24 of the non-return valve seat 18, is pressed vertically downwards against the flow direction of the hydrant 1 until the annular bead 26 of the non-return valve body 17 abuts the sealing slope 27 of the sealing plate 25, thus preventing further movement of the non-return valve body 17. Therefore, even with a significantly higher back pressure of the fluid in the central section 4 relative to the connection piece 2 or the fluid supply line, a reliable seal of the non-return valve 5 can be achieved via the annular bead 26 and the sealing slope 27, thus reliably preventing backflow of fluid into the fluid supply line in every operating condition.

[0031] As in Fig. As shown in Figure 7, the center piece 4 with the backflow preventer 5 and the sealing plate 25 can be pre-assembled as a unit and also removed from the Fig. The backflow-protected hydrant 1 shown in section 1 can be removed. Fig. 8 is finally hydrant 1 from Fig. Figure 1 shows the middle section 4 being removed. Existing hydrants can thus be easily connected to a Fig. The intermediate piece 4 shown in Figure 7 can be retrofitted accordingly to enable backflow protection. Since the connecting piece 2 and the outlet piece 6 are designed to connect directly to each other, but also to the intermediate piece made of... Fig. Since 7 components can be connected in between, the respective components can be used particularly easily and economically for different variants of the hydrant. Reference symbol list 1 Backflow-protected hydrant 2 connector pieces 3 connection flange 4 Middle section 5 Backflow preventer 6 Outlet piece 7 Main valve 8 Seal 9 screw 10 Mother 11 Main valve body 12 Main valve seat 13 Bottom of the main valve body 14 Cylindrical outer sealing surface 15 Cylindrical inner sealing surface 16 Introduction phase 17 Non-return valve bodies 18 Non-return valve seat 19 Cylindrical guide area 20 Bridge 21 Cylindrical bushing 22 ring disc membrane 23 Radial outer mounting area 24 Radial inner sealing area 25 Sealing plate 26 Ring ridge 27 sealing slope 28 sealing bead

Claims

[1] Backflow-protected hydrant (1) for connection to a liquid supply line comprising a main valve (7) and a backflow preventer (5) positioned upstream of the hydrant (1) in the outflow direction to prevent the backflow of contaminants into the liquid supply line, wherein the backflow preventer (5) comprises a backflow valve body (17) movable along a locking axis between a closed position and an open position and a backflow valve seat (18) corresponding to the backflow valve body (17), and the main valve (7) comprises a main valve body (11) movable from a closed position to an open position in the opposite direction to the flow direction of the hydrant (1) and a main valve seat (12) corresponding to the main valve body (11), characterized by , that the non-return valve seat (18) is designed to be movable along the locking axis. [2] Backflow-protected hydrant (1) according to claim 1, characterized by, that the non-return valve seat (18) is designed as a flexible annular disc diaphragm (22) with a radially outer mounting area (23) and a radially inner sealing area (24) for sealing contact with the non-return valve body (17). [3] Backflow-protected hydrant (1) according to claim 2, characterized by , that the radially inner sealing area (24) has a sealing bead (28) on the side facing the return valve body (17) for sealing contact with the return valve body (17). [4] Backflow-protected hydrant (1) according to claim 2 or 3, characterized by , that the radially inner sealing area (24) is movable relative to the radially outer mounting area (23) along the locking axis. [5] Backflow-protected hydrant (1) according to any one of the preceding claims, characterized by, that the non-return valve body (17) is designed to move in the closed position together with the non-return valve seat (18) in the direction of the locking axis. [6] Backflow-protected hydrant (1) according to one of the preceding claims, characterized by , that in the direction of flow of the hydrant (1) after the backflow valve seat (18) a sealing plate (25) is provided to support the backflow valve seat (18). [7] Backflow-protected hydrant (1) according to claim 6, characterized by , that the sealing plate (25) has a sealing slope (27) for the sealing system on an annular bead (26) arranged on the return valve body (17). [8] Backflow-protected hydrant (1) according to claim 7, characterized by, that the non-return valve seat (18) movable along the locking axis is movable between a position against the sealing plate (25) and a position deflected by the non-return valve body (17), in which the annular bead (26) of the non-return valve body (17) rests against the sealing slope (27) of the sealing plate (25). [9] Backflow-protected hydrant (1) according to any one of the preceding claims, characterized by , that the main valve body (11) is designed as a shut-off cone. [10] Backflow-protected hydrant (1) according to any one of the preceding claims, characterized by, that the non-return valve seat (18) is movable along the locking axis to such an extent that a reduction in volume of the space enclosed between the main valve (7) and the non-return valve (5) due to a movement of the main valve body (11) from the closed position can be compensated by a movement in the same direction of the non-return valve body (17) movable along the locking axis together with the non-return valve seat (18). [11] Backflow-protected hydrant (1) according to any one of the preceding claims, characterized by , that the non-return valve body (17) acts as a float with a density greater than 1.3 kg / dm³ 3 is designed and the backflow-protected hydrant (1) is arranged such that the float is acted upon by its weight in the direction of the backflow valve seat (18).

Images