Height-adjustable hydrant bottom part and method for adjusting the length of the riser in a hydrant bottom part

Abstract

The hydrant base comprises a riser pipe with a standpipe and a telescopic pipe arranged coaxially to the standpipe and mounted axially displaceably on this standpipe. A height adjustment device for adjusting the axial position of the telescopic pipe relative to the standpipe is arranged within the riser pipe. It comprises a first support (61) projecting inwardly on the standpipe (1), a second support (63) projecting inwardly on the telescopic pipe, and an adjustable spacer (65) with which the supports (61, 63) can be connected to one another at a predeterminable mutual distance.

Description

[0001] The subject matter of the invention is a height-adjustable hydrant base according to the features of patent claim 1 and a method for adjusting the length of the riser pipe in such a hydrant base according to the features of patent claim 14.

[0002] Fire hydrants are taps for water from a water main. They consist of a hydrant base with a riser pipe, which is usually connected to a water pipe in the water main via an inlet bend. In the lower part of the riser pipe or in a base below the riser pipe, the hydrant base contains a main valve assembly with a main valve body that can be moved between a closed and an open position from above via a main valve rod.

[0003] In underground hydrants, the lower section of the hydrant includes a coupling in the upper section of the riser pipe for connecting a downstream pipe. In installed underground hydrants, the upper section of the riser pipe and the coupling are located in a shaft. This shaft is covered by a surface cap at street level or, generally, at the level of the surrounding terrain.

[0004] In addition to the hydrant base, above-ground hydrants also include an upper hydrant section with at least one outlet coupling. The lower hydrant section includes a riser flange at the upper end of the riser pipe, to which the upper hydrant section is attached. The upper hydrant section includes a corresponding base flange for this purpose. The connection area between the lower and upper hydrant sections serves as a predetermined breaking point. In the event of an accident, e.g., if a vehicle crashes into the upper hydrant section, the hydrant breaks off at the predetermined breaking point. The main valve remains tightly closed and intact, so no water can escape.

[0005] In a fully installed hydrant, the riser flange must be positioned near ground level or at a defined low level relative to the surrounding terrain, for example, approximately 5 cm above ground level. Due to the varying depths of the water pipes in the water supply network relative to the surface level, riser pipes of hydrant bases of different lengths and heights are required. Previously, this required a large number of riser pipes of varying lengths. Subsequent ground subsidence or terrain shifts may require the replacement of riser pipes with different lengths. This requires complex and expensive excavation work.

[0006] CH689169A5 discloses a hydrant whose lower section comprises a two-part riser pipe. The lower section of the riser pipe comprises a casing pipe, which can be connected to a water pipe at the bottom via an inlet bend. The upper section of the riser pipe is designed as a telescopic pipe, which is mounted in the casing pipe so that it can be axially extended and can be attached to the casing pipe in stages that can be adjusted in height. For this purpose, the telescopic pipe has circumferential, evenly spaced annular grooves on its outside. To secure the telescopic pipe at a predetermined height, a snap ring is inserted into the corresponding annular groove. A clamping flange with an annular inner edge recess is placed on top of the snap ring and screwed to a connecting flange that projects radially outwards at the upper end of the casing pipe.A sealing ring is located between the snap ring and a contact surface of the connecting flange. This seals the gap between the telescopic pipe and the casing pipe when the clamping screws are tightened. Height adjustments of the riser pipe can only be made if the connection point with the connecting flange is accessible. This area is below the level of the surrounding terrain when the hydrant is installed at its intended location.

[0007] EP3862494A1 discloses another hydrant whose lower section comprises a two-part riser pipe with a fixed standpipe or casing pipe and a telescopic pipe mounted therein for axial height adjustment. Rack-like threaded segments are arranged along the inner wall of the casing pipe and mesh with an adjustment thread in the lower area on the outside of the telescopic pipe. By rotating the telescopic pipe, the height or length of the riser pipe can be continuously adjusted axially. When the telescopic pipe is rotated, the orientation of all elements arranged on the telescopic pipe or firmly connected to the telescopic pipe also changes. This applies in particular to elements such as outgoing couplings, which are arranged on the telescopic pipe or on a hydrant upper section connected to the telescopic pipe at a radial distance from the telescopic pipe axis, for example radially projecting outgoing couplings.

[0008] An object of the present invention is to provide a hydrant base with a standpipe and a telescopic pipe, wherein the telescopic pipe can be displaced in the axial direction of the standpipe while maintaining its rotational position and can be fastened to the standpipe in different axial positions. A further object of the invention is to provide a hydrant base whose height can be adjusted without excavating the surrounding soil.

[0009] This object is achieved by a hydrant lower part according to the features of patent claim 1 and by a method for adjusting the length of the riser pipe in such a hydrant lower part according to claim 14.

[0010] The hydrant's lower section comprises a two-part riser pipe with an inner pipe and a casing pipe. The casing pipe and inner pipe are arranged coaxially and mounted on each other for axial movement.

[0011] In different designs of the hydrant's lower section, either the inner pipe or the casing pipe can be permanently connected to a water pipe, for example, via an inlet bend. This lower pipe is called the standpipe, and the upper pipe, which is slidably mounted on the standpipe, is called the telescopic pipe.

[0012] The hydrant base includes a height adjustment device with which the axial position of the telescopic pipe relative to the standpipe, and thus the height or length of the riser pipe, can be adjusted. The height adjustment device can be designed to hold the telescopic pipe at the set height without additional fastening means. In alternative embodiments, additional fastening means can be provided for attaching or securing the telescopic pipe at the set height to the standpipe.

[0013] The height adjustment device is preferably arranged in the interior of the riser pipe such that it does not include any elements in the space between the inner pipe and the casing pipe. The space between the inner pipe and the casing pipe can thus be kept to a minimum, allowing for safe, guided movement of the casing pipe on the inner pipe or vice versa, taking manufacturing tolerances into account. The interior space delimited by the inner pipe has, at least in sections, a comparatively large diameter or, in general, a comparatively large cross-sectional area. The usable flow cross-section and the space available for inspection work are correspondingly large in these sections. Furthermore, extendable rods and associated bearings for actuating the main valve arranged below can be easily removed. In some embodiments, the telescopic pipe can be arranged as a casing pipe on the outside of the inner pipe.This has the advantage that almost no dirt or water can penetrate from the outside into the space between the inner pipe and the casing pipe and collect there. With a telescopic pipe arranged on the inside of the inner pipe, the space between the pipes is accessible from above, so that without additional protective measures, dirt and water can penetrate from above into this space and collect there. Effective sealing of the space, for example at the upper end of the casing pipe, could reduce the penetration of water and dirt, but would hinder the mobility of the telescopic pipe. Standing water in the space can freeze at sufficiently low temperatures and damage the lower section of the hydrant. Furthermore, germs can settle in the space between the pipes.

[0014] The height adjustment device comprises a first support projecting on the inside of the wall of the inner tube, vertically opposite thereto an associated second support projecting on the inside of the wall of the jacket tube and an elongated spacer with which the first support and the second support can be connected to one another at different mutual distances.

[0015] In alternative embodiments, the height adjustment device can also comprise a plurality of opposing first and second supports and / or a plurality of identical or different spacers. In particular, at least two or three spacers can be arranged, preferably evenly distributed, within the inner tube and the jacket tube. This can further stabilize the connection between the jacket tube and the inner tube. This can ensure, particularly in configurations with a short overlap area between the jacket tube and inner tube, that they maintain their coaxial alignment even under the influence of large transverse forces.

[0016] Preferably, the spacer or one of the spacers is a threaded spindle, in particular a threaded spindle with a trapezoidal thread. Such threaded spindles are preferably made of corrosion-resistant chromium steel. The threaded spindle is mounted on one of the supports so that it can rotate in a fixed vertical position. The other associated support has an internal thread that meshes with the external thread of the threaded spindle. The support with the internal thread is usually the first support. This is preferably arranged close to the end of the inner tube where the inner tube and the casing tube overlap. The second support is correspondingly arranged close to the end of the casing tube that lies outside the overlap area of ​​the two tubes.

[0017] The telescopic pipe is preferably designed as a casing pipe, which is arranged on the outside of the standpipe and mounted on it for axial displacement, so that the length or height of the riser pipe can be adapted to individual conditions at different installation locations. This ensures that the free cross-sectional area inside the riser pipe is not reduced by the telescopic pipe. On the contrary, the free cross-sectional area of ​​the telescopic pipe is larger in a section extending axially beyond the standpipe than below it in the area of ​​the standpipe. The usable flow cross-section inside the standpipe is not restricted in such designs, and the space available for inspection work is correspondingly large.

[0018] Sealing and connecting means for sealing and connecting the casing pipe to the standpipe can be arranged completely inside the riser pipe in such hydrant lower sections and are easily accessible from the inside.

[0019] This facilitates both the adjustment of different lengths and heights of the riser pipe and inspection work on the hydrant.

[0020] In alternative embodiments, the standpipe can also be designed as a jacket pipe and the telescopic pipe can be mounted on the inside of the standpipe so that it can be axially displaced.

[0021] The height of the riser pipe can be easily adjusted on the hydrant base without excavation. In particular, the height can be continuously adjusted while maintaining the alignment of the telescopic pipe. Maintenance work can be carried out even when water is under pressure in the water line to which the hydrant base is connected. In particular, it is also possible to adapt the length of the hydrant base to the changed environment, for example, in the event of terrain shifts or subsidence, essentially without excavating the surrounding soil.

[0022] The invention is explained in more detail below with reference to some figures. Figure 1 shows a half-section of a hydrant lower part, Figure 2 shows a half-section in the area of ​​a guide at the lower end of a main valve spindle, Figure 3 shows a half-section in the area of ​​the main valve, Figure 4 shows a detailed cross-section in the area of ​​a guide ring, Figure 5 shows a perspective view of a cut-open hydrant lower part in a first configuration, Figure 5 shows a perspective view of the cut-open hydrant lower part from Figure 5 in a second configuration, Figure 7 shows a half-section in the area of ​​a spindle bearing, Figure 8 shows a partial half-section in the area of ​​a height adjustment device, Figure 9 shows a detailed cross-section in the area of ​​a bearing holder.

[0023] The Figure 1The hydrant lower part, shown in section, comprises a riser pipe with an inner pipe 1 and a casing pipe 3 arranged on the outside coaxially to the inner pipe 1 and mounted on the inner pipe 1 so as to be displaceable along a common pipe axis A. A base 5 is attached to the bottom of the inner pipe, in which base 5 a main valve with a valve seat 7 and a valve body 9 is arranged, the valve body 9 being movable between an open position and a closed position at the valve seat 7 by means of a main valve spindle 11. The inner pipe 1 in this embodiment is a standpipe which can be firmly connected to a water pipe via the base 5 and an inlet bend (not shown). A drainage pipe 13 is arranged on the side of the base 5, which allows drainage of the riser pipe via an opening in the base 5 when the main valve is closed. The casing pipe 3 in this embodiment is a telescopic pipe mounted on the standpipe so as to be axially displaceable.To set a preset height or length L1 of the riser pipe, the jacket pipe 3 or telescopic pipe can be moved into the appropriate position relative to the inner pipe 1 or standpipe and fastened to the inner pipe 1.

[0024] At the lower end of the jacket tube 3 overlapping with the inner tube 1, a centering ring 15 is arranged, which holds the jacket tube 3 at a small radial distance L2 of, for example, about 4 mm to about 8 mm coaxially to the adjacent section of the inner tube 1. This detail is shown in Figure 4shown enlarged. The centering ring 15 comprises a substantially cylindrical upper section B, the thickness L3 of which is slightly smaller than the radial distance L2 between the inner tube 1 and the casing tube 3. The thickness L3 can, for example, be in the order of magnitude of 70% to 85% of L2. The inner diameter of the centering ring 15 essentially corresponds to the outer diameter of the inner tube 1 plus a slight play, so that the centering ring 15 can be mounted on the outside of the inner tube 1 so that it can be easily axially displaced. The centering ring stabilizes the coaxial arrangement of the casing tube 3 and the inner tube 1. The centering ring 15 is preferably slotted, ie it comprises a continuous gap so that the adjacent end sections can be elastically pulled apart during assembly. On the outside, one or more circumferential ribs 17 or rib sections protrude from the upper cylindrical section B of the centering ring 15.In the area of ​​these ribs 17, the thickness of the centering ring 15 is greater than the gap width L2 between the inner tube 1 and the casing tube 3. Adjacent to the upper section B at the bottom, the centering ring 15 comprises a section C with a radially projecting shoulder, preferably with a wedge-shaped cross-section. The shoulder comprises a stop surface 19 which, when the flat section B is pushed into the space between the inner tube 1 and the casing tube 3, defines an end position of the centering ring 15 by bearing against the front end of the casing tube 3. In the end area, the casing tube 3 comprises one or more circumferential grooves 21 or groove sections on the inside. The arrangement and dimensions of these grooves 21 are dimensioned such that they can accommodate the projecting ribs 17 of the centering ring 15 in its end position.The centering ring 15 is preferably made of an abrasion-resistant and weather-resistant plastic, for example POM (polyoxymethylene) or PE (polyethylene). In section C, the centering ring 15 can comprise one or more additional ribs 17' projecting on the inside. These rest on the outside of the inner tube 1. When the centering ring 15 is pushed axially into the end position, it can be slightly elastically deformed in the upper, cylindrical section B, so that the ribs 17 can overcome the inner wall sections of the casing tube 3, which act as an obstacle, until they reach the grooves 21. Due to the rigidity and elasticity of the centering ring 15, the ribs 17 are resiliently pressed into the grooves 21 in the end position. This anchors the centering ring 15 to the front end of the casing tube 3. The centering ring 15 also has a protective function by preventing the penetration of dirt into the space between the inner tube 1 and the jacket tube 3.If water penetrates into the intermediate space, it can then flow out again through the gap in the centering ring 15 through the opening in the intermediate space located at the bottom. Alternatively or additionally, the centering ring 15 could, for example, have structures on the inside such as recessed grooves or protruding knobs. When the centering ring 15 is installed, connecting channels are created between the inner pipe 1 and the centering ring 15, which continuously connect the intermediate space to the outside and ensure that water can drain out of the intermediate space. Optionally, the intermediate space can be sealed off from the outside, for example by means of an annular sealing element. This can prevent, for example, groundwater from the outside into the intermediate space. The conical wedge surface in section C also acts as a deflector, which can displace surrounding soil when the casing pipe 3 and the inner pipe 1 are pressed down or pushed together.Another advantage is that the outer diameter of the jacket tube 3 is only slightly larger than the outer diameter of the inner tube 1, for example, approximately 20 mm to approximately 40 mm. This means that the volume of surrounding material to be displaced when the jacket tube 3 and the inner tube 1 are pushed together is comparatively small.

[0025] The Figures 2 to 4 show details in the lower part of the hydrant base, the Figures 7 to 9those in the upper area of ​​the hydrant base. A spindle nut 23 is arranged coaxially to the valve body 9 on its upper side and is connected to the valve body 9 in a rotationally fixed manner. Two fingers 25, which are diametrically opposed, protrude radially from the spindle nut 23. The ends of the fingers 25 engage with two diametrically opposed longitudinal guides 27 on the inside of the inner pipe 1. The longitudinal guides 27 can, for example, in the case of die-cast inner pipes 1, be designed directly as structures of the inner pipe 1. Alternatively, longitudinal guides 27 can be fastened to the inside of the inner pipe 1 using known fastening techniques. The longitudinal guides can in particular each comprise two guide strips arranged parallel to one another, which protrude inwards on the inside of the inner pipe 1 and together delimit a guide groove for the respective finger 25.In general, the fingers 25 define a first guide means arranged on the spindle nut 23 in a rotationally fixed manner with respect to the axis of rotation A, and the longitudinal guides 27 define a second guide means which interacts with the first guide means and limits the range of movement of the first guide means to movements required to move the valve body 9 between an open position and a closed position at the valve seat 7. The main valve spindle 11 comprises, at the lower end of a primary rod section 31, an external thread which meshes with the internal thread of the spindle nut 23. At the upper edge of the inner tube 1, a primary spindle bearing 33 is arranged, on which the primary rod section 31 is rotatably mounted in a fixed, predetermined axial position on the inner tube 1. The primary spindle bearing 33 can be secured in the predetermined axial position, for example, by means of retaining rings.The primary spindle bearing 33 comprises a yoke with two diametrically opposed arms 35 with peripheral edge recesses 37 for receiving radially inwardly projecting upper edge sections 39 of the inner tube 1. As a result, the primary spindle bearing 33 is anchored to the inner tube 1 and designed as an abutment for absorbing axial compressive forces which are transmitted from the valve body 9 via the primary rod section 31 to the primary spindle bearing 33. No compressive forces from the valve body 9 are transmitted to the casing tube 3. Preferably, the primary spindle bearing 33 is held against rotation on the inner tube 1 by a securing means. For this purpose, the edge sections 39 of the inner tube 1 can, for example, comprise bores into which a spring pin 49 is each inserted when the arms 35 of the spindle bearing 33 are fastened to the edge sections 39. The spring pins 49 prevent rotational movements of the spindle bearing 33 anchored to the inner tube 1.The primary spindle bearing 33 and its anchoring on the inner tube 1 can also be designed in a different way and are not limited to the embodiment described here.

[0026] The primary rod section 31 is preferably a square tube or, more generally, a polygonal tube. An adjustable secondary rod section 41 is axially displaceable and non-rotatably mounted in the primary rod section 31.

[0027] In an upper end region, the secondary rod section 41 is rotatably mounted and anchored in the upper end region of the casing tube 3 in a similar manner to the primary rod section 31 by means of a secondary spindle bearing 43 with radially projecting arms 45. For this purpose, protruding, C-shaped rib sections 47 can be provided, for example, on the inside of the wall of the casing tube 3 as receptacles for the end sections of the arms 45. By a slight rotational movement, the arms 45 can be inserted into these receptacles. As in Figure 7 As shown, the arms 45 can be secured in the receptacles, for example, by means of spring pins 49 inserted through holes in the rib sections 47. Alternatively, webs or other structures could protrude from the inside of the wall of the casing tube 3, and the arms 45 could comprise U-shaped profiles for receiving these webs or other structures.

[0028] The secondary rod section 41 is slidably mounted within the primary rod section 31 and moves with it when the axial position of the casing pipe 3 changes. In contrast to the primary spindle bearing 33 and its anchoring to the inner pipe 1, the secondary spindle bearing 43 and the rib sections 47 do not have to absorb any compressive forces from the valve body 9. They can therefore be designed much more simply and require less space. This facilitates access from above to the interior of the hydrant base. For inspection purposes, the secondary spindle bearing 43 and the secondary rod section 41 can simply be separated from the casing pipe 3 and pulled out after the spring pin(s) 49 have been removed from the rib sections 47.

[0029] To open and close the main valve, the main valve spindle 11 is rotated via the main valve rod 31, 41 directly or indirectly via an extension on the upper part of the hydrant, e.g., using a hydrant wrench. The fingers 25 engaging in the guides 27 prevent the spindle nut 23 from rotating with the main valve spindle 11. When the main valve spindle 11 is rotated, the spindle nut 23 is guided upwards or downwards together with the valve body 9.

[0030] Optionally, a centering ring 24 can be arranged on the outside of the spindle nut 23, the outer diameter of which is larger than that of the spindle nut 23 and smaller than or equal to the smallest inner diameter of the inner tube 1 in the area of ​​the longitudinal guides 27. This facilitates the positioning of the main valve spindle 11, for example during inspection work.

[0031] The inner tube 1 is sealed against the jacket tube 3 by means of a sealing ring 51, which is clamped between an outer chamfer or a beveled edge on the upper edge of the inner tube 1 and a clamping flange 53. The upper edge of the inner tube 1 preferably includes a small, radially outwardly projecting shoulder, which serves as a guide for the jacket tube 3. The gap between the chamfered upper edge of the inner tube 1 and the adjacent jacket tube 3 is therefore very small. This prevents the sealing ring 51 from penetrating the gap and becoming undesirably jammed.

[0032] The clamping flange 53 also has a chamfered outer edge and is preferably attached to the inner tube 1 by means of three screws. For this purpose, the inner tube 1 includes inwardly projecting sections with corresponding internal threads at the upper edge. When the screws are tightened, the sealing ring 51 is clamped between the chamfered areas of the inner tube 1 and the clamping flange 53 and pressed from the inside against the casing tube 3. Preferably, the sealing ring 51 has a trapezoidal cross-section that is adapted to the chamfered areas of the inner tube 1 and the clamping flange 53. This ensures a particularly secure seal. The mechanical stress on such sealing rings 51 is comparatively low, and their service life is correspondingly long.

[0033] The hydrant base includes a height adjustment device that enables continuous axial displacement of the casing pipe 3 relative to the inner pipe 1 and the attachment or retention of the casing pipe 3 to the inner pipe 1 in different positions or heights. The height adjustment device is arranged entirely within the riser pipe, which is defined by the inner pipe 1 and by the casing pipe 3 connected to the inner pipe 1.

[0034] In principle, the casing pipe could also be sealed against the standpipe in another way, for example with one or more O-rings, X-rings or radial shaft seals.

[0035] The height adjustment device comprises a first support 61 projecting on the inside of the inner tube 1, a second support 63 projecting on the inside of the wall of the casing tube 3, and an elongated spacer 65, with which the first support 61 and the second support 63 can be connected to one another at different mutual distances. The spacer is preferably a threaded spindle 65', in particular a threaded spindle 65' with a trapezoidal thread. The threaded spindle 65' is preferably made of corrosion-resistant chromium steel. The threaded spindle 65' is mounted on the second support 63 so that its height can be changed without change and can be rotated. This can be achieved, for example, by means of two stop bodies 67, which project radially above the threaded spindle 65' at the top and bottom and are connected to the threaded spindle 65' in a rotationally fixed manner at the upper end thereof. A polygonal profile, in particular a square profile, is formed on the upper stop body 67.Preferably, this polygonal profile and the heads of the screws for tightening the clamping flange 53 are of the same design so that they can be operated by means of a socket wrench with the same socket.

[0036] The first support 61 includes an internal thread that meshes with the threaded spindle 65'. The first support 61 is arranged near the upper end of the inner tube 1, where the inner tube 1 and the jacket tube 3 overlap. The second support 63 is arranged correspondingly near the upper end of the jacket tube 3, outside the overlap area of ​​the two tubes.

[0037] By turning the threaded spindle 65', the height of the second support 63 and the casing tube 3 connected thereto changes relative to the height of the first support 61 and the inner tube 1 connected thereto. With the screws of the clamping flange 53 loosened, the casing tube 3 can be moved axially to the desired height by turning the threaded spindle 65'. As a rule, the holding force of the threaded spindle 65' is sufficient to hold the casing tube 3 in the set height on the inner tube 1. Optionally, a safety device can be provided which secures the threaded spindle 65' in a force-fitting and / or form-fitting manner in the respective rotational position, e.g. on the first support 61 or on the second support 63. Alternatively, e.g.a further stop body can be connected to the threaded spindle 65' at a predeterminable height, wherein this further stop body is arranged in the set extension position of the telescopic tube directly above adjacent to the first support 61 and prevents further lowering of the threaded spindle 65' by contacting this first support 61 (not shown).

[0038] Preferably, the height adjustment device comprises means for limiting the maximum extension length of the telescopic tube, for example a limiting body 69 ( Figs. 5 and 6 This ensures that the overlap area of ​​the telescopic tube and the standpipe at maximum extension length is sufficiently large to maintain the coaxial arrangement of the two tubes even under the influence of external transverse forces.

[0039] Alternatively, means for limiting the maximum extension length of the telescopic tube could comprise a first limiting body arranged on the telescopic tube and projecting into the space between the telescopic tube and the standpipe, and a second limiting body on the standpipe that interacts with the first limiting body (not shown). In the maximum extended position of the telescopic tube, the two limiting bodies are in mutual contact and prevent further extension of the telescopic tube. The first limiting body is preferably arranged in the end region of the telescopic tube and is connected directly or indirectly to the telescopic tube by the centering ring 15. The second limiting body is, for example, a radially projecting edge section of the standpipe. The first limiting body can, for example,comprise a flat spring, which is held in one end region by the centering ring 15 in a matching recess on the telescopic tube, and which projects into the space between the telescopic tube and the standpipe. Such flat springs can be elastically deformed and pressed against the wall of the telescopic tube when the telescopic tube and the standpipe are pushed together, thus overcoming the obstacle of the second limiting body. The free end sections of the flat springs then snap back into the space and from then on function as first limiting bodies. When the end position is reached, an axial compressive force from the second limiting body acts on the first limiting body. The first limiting body is supported by the edge of the recess on the telescopic tube, so that the centering ring 15 is not loaded by an axial force and maintains its position.When the jacket pipe 3 is connected to the inner pipe 1 at the height required at the respective location, the space between the two pipes is sealed by the sealing ring 51, which is pressed radially against the jacket pipe 3 and axially against the inner pipe 1 by the force of the clamping flange 53.

[0040] In alternative embodiments of the hydrant lower section, the casing pipe 3 could be used as a standpipe and the inner pipe 1 as a telescopic pipe. A height adjustment device can also be provided in such embodiments. In contrast to the previously described embodiments, in which the inner pipe 1 is the standpipe 1, the corresponding specifications apply to the casing pipe 3 as the standpipe and to the inner pipe 1 as the telescopic pipe.

[0041] In further embodiments of the hydrant lower part, the spindle nut 23 and the main valve spindle 11 could also be arranged interchangeably, so that a main valve spindle 11 with an external thread is arranged at the top of the main valve body 9 and a spindle nut 23 with an internal thread is arranged at the bottom of the main valve rod.

[0042] In further embodiments of the hydrant base, the main valve can be moved between an open position and a closed position, for example, by rotating the main valve body 9 about the main valve axis A. Although the device for opening and closing the main valve is designed differently, such hydrant bases can include a height adjustment device for adjusting the axial position of the telescopic pipe relative to the standpipe, as described above.

Claims

1. Hydrant lower part comprising a riser pipe with a standpipe connectable to a water pipe and a telescopic pipe arranged coaxially to the standpipe with respect to a rotation axis (A) and mounted on the standpipe so as to be displaceable in the direction of the rotation axis (A), characterized in that a height adjustment device for adjusting the axial position of the telescopic tube relative to the standpipe is arranged within the riser tube, wherein a first support (61) protrudes on the inside of the standpipe and a second support (63) protrudes on the inside of the telescopic tube, and wherein the first support (61) and the second support (63) are connected to one another by means of an adjustable spacer (65) at a predeterminable mutual distance.

2. Hydrant base according to claim 1, characterized in thatthe spacer (65) comprises a threaded spindle (65') with an external thread, that the first carrier (61) comprises an internal thread meshing with the external thread of the threaded spindle (65'), and that the threaded spindle (65') is rotatably mounted on the second carrier (63) in a defined axial position.

3. Hydrant base according to one of claims 1 or 2, characterized in that the standpipe is an inner pipe (1) and the telescopic pipe is a casing pipe (3) which is axially displaceable on the outside of the inner pipe (1).

4. Hydrant base according to one of claims 1 or 2, characterized in that the standpipe is a casing pipe (3) and the telescopic pipe is an inner pipe (1) which is axially displaceable on the inside of the casing pipe (3).

5. Hydrant base according to one of claims 2 to 4, characterized in thata centering ring (15) is arranged at the end of the jacket tube (3) overlapping with the inner tube (1), said centering ring having a cylindrical section engaging in the space between the jacket tube (3) and the inner tube (1).

6. Hydrant base according to claim 5, characterized in that the centering ring (15) in the cylindrical section comprises at least one outwardly projecting rib (17) and the casing tube (3) comprises at least one groove (21) on the inside for receiving the rib (17) in an end position of the centering ring (15).

7. Hydrant base according to one of claims 5 or 6, characterized in that the centering ring (15) comprises, adjacent to the cylindrical portion, a portion with a radially projecting shoulder having a stop surface (19), and in that the centering ring (15) comprises, in this portion, one or more internally projecting ribs (17').

8. Hydrant base according to one of claims 1 to 7, characterized in thata sealing ring (51) is held pressed by means of a clamping flange (53) against the edge of the inner tube (1) overlapped by the jacket tube (3) and against the inside of the wall of the jacket tube (3).

9. Hydrant base according to claim 8, characterized in that the edge of the inner tube (1) overlapped by the casing tube (3) and the edge of the clamping flange (53) arranged opposite thereto comprise externally chamfered areas, and that the sealing ring (51) bears against the inner tube (1) and the clamping flange (53) as well as the inside of the casing tube (3) in these chamfered areas.

10. Hydrant base according to one of claims 1 to 9, characterized in thatin the lower region of the standpipe or in a base (5) below the standpipe, a main valve assembly with a valve seat (7) and a main valve body (9) is arranged, that a main valve rod is mounted on the inner tube (1) by means of a primary spindle bearing (33) so as to be rotatable about the axis of rotation (A), and that at the bottom of the main valve rod there is arranged a main valve spindle (11) with an external thread which meshes with an internal thread of a threaded nut (23) arranged at the top of the main valve body (9).

11. Hydrant base according to claim 10, characterized in thata first guide means is arranged on the spindle nut (23) in a rotationally fixed manner with respect to the axis of rotation (A), and that a second guide means cooperating with this first guide means is arranged on the standpipe in a rotationally fixed manner with respect to the axis of rotation (A), wherein this second guide means limits the range of movement of the first guide means to movements which are necessary for moving the valve body 9 between an open position and a closed position at the valve seat 7.

12. Hydrant base according to one of claims 10 or 11, characterized in that the main valve rod comprises a primary rod section (31) which is rotatably held on the inner tube (1) by means of the primary spindle bearing (33), and that a secondary rod section (41) is axially displaceably mounted on the primary rod section (31) and rotatably mounted on the telescopic tube by means of a secondary spindle bearing (43).

13. Hydrant base according to one of claims 1 to 12, characterized in that the height adjustment device comprises a limiting body (69) which can be fastened to the spacer (65) at different heights or a limiting body which can be fastened to the telescopic tube and which is used to limit the maximum extension length of the telescopic tube, or that means are provided for limiting the maximum extension length of the telescopic tube, which means comprise a first limiting body arranged on the telescopic tube and protruding into the space between the telescopic tube and the standpipe, and a second limiting body on the standpipe which interacts with the first limiting body.

14. A method for adjusting the length of the riser pipe in a hydrant with a height adjustment device according to one of claims 1 to 13, characterized in thatthe telescopic pipe with the inside second support (63) is displaced relative to the standpipe with the inside first support (61) without excavation work on any surrounding soil, and that the first support (61) and the second support (63) are connected to one another within the riser pipe by the adjustable spacer at a predeterminable mutual distance.

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