DESCRIPTION AND APPLICATION

The hydrant network is made of a system of fixed pipes for the water supply to which one or more fire fighting hydrants, fire hoses, motor-pump connections, ground and underground hydrant systems etc. are connected. The network is linked to one or more water supplies through a manifold; fire fighting hydrants can be connected through a unified fitting equipped with an on-off valve manually operated.

The hydrant network must be equipped with one or more delivery connections for the fire trucks of the Fire Brigades having an on-off valve and a double deck valve together with fire hose connections. These connections represent a subsidiary water supply and must have one or more inlet emission UNI 70 with a swivel filter so as to avoid the entrance of unwanted bodies, an on-off valve, a shut off valve and a special device to avoid leakage of water in the pressurised system.

Water supplies must be arranged in order to always keep the system in good efficiency, therefore they must guarantee the requested pressure and flow capacity.

The UNI 10779 norm defines the minimum requirements for hydrant systems both for their installation and functioning introducing the criterion of internal and external protection and considering the hydrant networks as a real and fixed fire protection system fully integrated.

Buildings with a gutter height of more than 45 metres are not contemplated in the UNI 10779 norm as well as open door activities as frost can cause functioning problems.

The UNI 9490 norm also defines the requirements for ground and underground pipes. The on-off valves must be of the type UNI 6884 indicating the on-off position or of the gate type UNI 7125. As far as underground hydrants, they must be clearly indicated and by no means must hindrances to their operation exist.

The installation of a hydrant network must take into account the reliability of the entire system; the ring closure of collectors and the on-off valves in suitable places are key factors for an adequate level of functioning.
Pipes of hydrant networks must be emptied without necessarily dismantling its main components and must not be exposed to damages. Frost is a problem that must not be underscored so in locations where winter temperature can be below zero, pipes must be protected with insulation material.
Hydrant systems to be installed in seismic areas of 1, 2, 3 degrees must be in a position to resist to earth movements without the risk of breakage.

When pipes of a hydrant network cross vertical or horizontal structures of the building, precautions must be adopted in order to avoid deformation or damages to the fittings.
In any case the supports of the network must be non combustible; collars must be closed around the pipes and open supports must not be used.
The norm provides for the diameter, section and thickness of the supports.

Ground hydrants must be placed at a maximum distance between them of 60 meters and their maximum distance to external walls of the buildings must lie between 5 and 10 meters.

As far as wall hydrants are concerned, these must be installed considering that each unit must be able to protect no more than 1000 sq. meters and that each point of the protected area must be at a maximum distance of 20 meters from it.