Polish law strictly regulates issues related to the installation of hydrants and the entire fire protection system in buildings. The choice of the hydrant variant is not random, but strictly regulated by appropriate regulations, such as: the Fire Protection Act, the Regulation of the Ministry of the Interior and Administration on fire protection of buildings, other construction objects and areas, etc. So - which hydrants to choose?
Internal hydrant
Inside buildings, it is important to take care of proper fire protection. Internal hydrants can often be found, mainly in public buildings, shopping malls, etc. They look like small cabinets, hung in visible places on the walls.
Currently, three variants are used: DN25, DN30 and DN52, depending on the type of building in which they will be installed. It can be seen that depending on the diameter, hydrants are available with a semi-rigid hose (DN25 and DN30) or a flat hose (DN52).
In internal hydrants, attention should be paid to the length of the hose. For DN25 and DN30 hydrants, where a semi-rigid hose is used, variants of 25 or 30 m are available, while for DN52 hydrants, the following hose lengths are available: 15 m, 20 m or 20 + 20, which is a solution used when the emergency exit is more than 30 m away.
When choosing hydrants for the interior of a building, you can choose surface-mounted or concealed, in various colors. The most important thing, however, is that the hydrant is properly marked.
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Outdoor hydrant
External hydrants are one of the elements of the landscape that can often be observed, for example, along roads. According to the law, they must be located along roads and streets and at intersections, while maintaining appropriate distances from each other, from the edges of streets, etc. Such a layout is important for fire services, because it ensures appropriate and quick access to water during firefighting operations, but located near large plants and companies allow for the expansion of the safety network. The type of hydrant that should be chosen depends on several factors.
One of the key parameters to consider is the nominal diameter of the hydrant. External hydrants with a nominal value of DN80 are usually installed on the water supply network, although Polish law allows the use of variants with DN100 if they are located near buildings whose potential fire extinguishing needs require a capacity of at least 30 dm3/s.
It is assumed that both in the case of a ground hydrant and an underground hydrant DN80 , its nominal capacity at a water pressure of 0.2 MPa at the hydrant valve at the moment of water collection cannot be lower than 10 dm3/s. However, for models with DN100 - it must be at least 15 dm3/s.
Hydrant connection
The type of connection to the hydrant is selected depending on the hydrant variant. The main parameter is of course the diameter, allowing the fire hose to be attached in a dangerous situation. It is assumed that for hydrants 25 a DN25 connection should be used, for hydrants 33 and 52 a DN50 connection, while for hydrants 52 it is necessary to use a DN80 connection.
It should be remembered that the entire fire protection system is made based on a previously prepared project, taking into account the specific needs of a given facility. On this basis, appropriate hydrants are selected along with their matching connections.
Building size and hydrant selection
The choice of a hydrant is not a random decision, because there are strictly defined legal rules regarding fire safety. They concern both the size of the surface and the type of building in which they are to be located, e.g. in public utility buildings the DN25 variant is used, while in closed underground car parks DN30, and in warehouses and production halls as much as DN 52.
It is assumed that the selection of the appropriate hydrant variant and the location of the fire protection network depends primarily on the height of the building. There are medium-high buildings (up to 12-25 m high), high buildings (from 25-55 m) and high-rise buildings (when h>55 m). Hydrants with a DN52 valve should be located on each storey of high-rise and high-rise buildings, while in the case of DN25 hydrants - on each storey in high-rise and high-rise buildings, if the residential premises do not occupy the entire area of a given storey.