Fire hydrant

A hydrant ( from Greek hydor ὕδωρ 'water' ) is a device for the removal of water from a water distribution system. As a rule, be determined by the water utilities, fire hydrants used as part of the central fire water supply of cities and towns. He allows the fire department, but also public (eg road maintenance, urban enterprises) and private ( eg street cleaning companies, tent festival organizers ) users of water removal from the public water supply network (collective water supply).

Special signs point to underground hydrants in public space.

• 2.1 standpipe

• 3.1 hydrants directory

Hydrant

The hydrant ( in Upper Austria hydrant ) is above ground permanently installed and has several outlets with standard couplings, usually in the nominal size B or C and rarely also A. This is also dependent on the diameter of the supply line. The A- disposal is mostly used in industry and in large residential facilities in order to remove large amounts of water from the mains can. Since tubes of size A are present only as suction hoses for most fire departments, the water removal via the A - disposal must be done with caution. If a larger amount of water discharged as the hydrant can provide, the pump goes into the suction on which can lead to serious damage to the pipeline network. For the fire service is the delivery of the hydrant important. As a rule of thumb, the flow rate in liters / minute for the hydrants out of the 12 results - up to 15 times the nominal diameter (. , For example, H100: min 1200 l / min up to 1500 l / min. ).

Hydrant with drop jacket

The case jacket hydrant is a subspecies of the hydrants. The B -extractions, each with its own shut-off will be covered with a drop coat which protects it from dirt and damage. The finish with a nominal size of A is used mostly for particularly endangered objects, such as airports and industrial plants.

To start up the hydrants a triangle is dissolved in the hydrant head with the inner triangle the hydrant key, causing the drop jacket slides down and the upper Entnahmeventile releases. By rotating the entire head of the valve cone is opened, the air contained in the column to escape by the water flowing through a vent valve, also called picking bolts. The Wish bolt also prevents the closure of the case jacket before the hydrant is not closed and the water column was degraded via the independent emptying. So freezing is prevented.

Folding Coat hydrant or " Age Munich "

In Munich there are so-called folding sheath hydrants that were installed at the beginning of the 19th century. Today, only a few exist functional. These hydrants need to run a special hydrant wrench. Another special feature is the left -closing valves.

Underground hydrant

The underground hydrants are located below a hydrant cap that is installed flat in the street. The lid of the hydrant cap is lifted with the slide key and swung to the side, causing the Hydrantenfuß is accessible.

The underground hydrant allows the connection of a standpipe. Hydrants have the disadvantage that they can be zugeparkt of motor vehicles or frozen by snow or ice, and thus are often not usable. The freezing of the lid in the hydrant cap can be largely avoided by greasing of both parties or by inserting a plastic sheet. Württemberg shaft hydrants are common in parts of Württemberg. They were preferred because they sit about 1 meter deeper than the normal hydrants, and thus the risk of Zufrierens is bypassed during cold winters. Originally these hydrants come from England, which were patented in 1840 by Simpson.

For Hydrants is an accurate designation by signs that indicate the exact position of the hydrants, very important. The signs indicate the direction forward and lateral distance from the hydrant sign in meters. The flow rate (liters / minute ) of an underground hydrants may by rule of thumb from the 7 - to be calculated to 10 times the nominal diameter ( for example: H80 results in at least 560 l / min up to 800 l. / Min. ).

Standpipe

The standpipe is a valve for water extraction from the public water supply network via underground hydrants. It consists of a long stand base with a handle, a claw nut at the base of the tube with a sealing ring and a short standpipe top with stuffing box and gland, above it there are two Niederschraubventile with one or two fixed couplings.

The standpipe is attached to the handle by turning on the hydrant seat, the claws nut is held high and screwed into the jaw of the underground hydrants; thus the sealing ring is pressed firmly to the underground hydrants and closes it tight even at higher pressures from.

The gland is connected by two screws to the handle, thus the standpipe upper part can be rotated through the gland in a more favorable situation; this should always be done by turning clockwise to prevent the claws nut from rotating out of the claw and the standpipe shoots under pressure into the air.

The Adapters allow it to connect two hoses to the standpipe. Ahead of them are the Niederschraubventile, which must share the entire flow cross section in the open state. In this case, any leaks caused by the construction of the valves must be easy to fix. The valve plates are mounted and secured against loosening by itself.

Standpipes for fire fighters are standardized with two B couplings according to DIN 14 375. They weigh no more than 7.5 kg, and are tested at 25 bar for tightness, the valves on each 16 bar. Standpipes with two C - Adapters are not standardized.

To use a stand pipe, a valve key is required, with which the hydrant pit and the hydrant are even open. Before the hose is connected to the hydrant, it must be purged through the standpipe, so that stones and impurities from the line, the pump can not damage it. In addition, the standpipe to the road must be secured.

In addition to the uniform standardized by DIN 14 375 standpipe and the 1.95 m long standpipes for Wuerttemberger shaft hydrants are sometimes used.

Hydrant all types have a foot valve, which acts simultaneously as emptying. This valve is moved by a rod from the top of the hydrant or slide key at the underground hydrants. Normally, the hydrant is anhydrous and may therefore not freeze well. Draining is either a gravel bed or the storm sewer.

Standpipes also be used by the water supplier for drinking water supply at carnivals, fairs and similar events. Often they are then fitted with a water meter.

Locating the hydrant

Special Hydratenhinweisschilder point to underground hydrants in public space.

Hydrants directory

As hydrants directory ( hydrants plan ) is called a (now also locally available digital ) street plan in which all hydrants, open water and underground water tank are registered. The map is maintained by the local water utility or municipal office.

Some fire departments keep hydrants directories now in the fire engine is usually in the crew compartment willing to allow the location of fire hydrants explored already on the journey to the operation site and the vehicle lineup can be set accordingly.

Within the project OpenStreetMap is a special map under construction. This shows the location and further information about fire stations, fire hydrants and medical emergency rooms.

Relevant standards / regulations

In Germany and Austria the relevant standards are largely harmonized with the European standards. In addition, within the norms are still free spaces both in the application and in the design that are not described in detail here.

• DIN EN 14339 " Hydrants " (replacement for DIN 3221 )
• DIN EN 14384 " hydrants " (replacement for DIN 3222 )
• DIN 3321 " Specification and approval tests for fire hydrant "
• ÖNORM F 2010
• EN 1074-6 " Valves for water supply - Fitness for purpose requirements and appropriate verification tests - Part 6: Hydrants "
• DVGW eV: Technical Note, Data Sheet W 331, selection, installation and operation of hydrants. DVGW German Association of Gas and Water Association, Bonn 2006, ISSN 0176-3504.
• DVGW eV: Technical rule worksheet W 405, the provision of fire-fighting water from the public drinking water supply. DVGW German Association of Gas and Water Association, Bonn 2008, ISSN 0176-3504.

International differences

The public water main is laid in Central Europe below the frost line in the ground. Hydrants have a shut-off ( slide ), which is also mounted in corresponding depths of the earth. After closing the shut-off piping between shut-off and fire hydrant ( riser ) is emptied by a valve so that the frost resistance is restored. In international parlance this is called a "dry barrel" hydrant.

In areas without danger of frost, this arrangement is not necessary. The riser is filled with water. Barrier elements are only above ground or below ground level directly available. This type is called "wet barrel" hydrant.