The main difference between portable and trolley fire extinguishers is that the seconds, which have a mass exceeding 20 kg, are too heavy to be carried by hand and at the same time manoeuvred easily by one person. However, the trolley fire extinguishers have charge, delivery per unit of time and greater range, so they can extinguish more quickly and with the use of fewer people, fires that would otherwise require the contemporary and coordinated commitment of many people with Portable fire extinguishers to be extinct. They are therefore used in cases where the intervention with the portable fire extinguishers proves insufficient.
The classification of the extinguishing capacity of the wheeled extinguishers is regulated by Ministerial Decree 6 March 1992:
' Technical and procedural standards for the classification of extinguishing capacity and for the approval of fire-safety fire extinguishers '
This decree provides that the evaluation of the characteristics and performance, as well as the classification of fire-wheeled extinguishers, are carried out as specified in standard UNI 9492. The same technical standard applies to the formulation of the opinions issued by the Ministry of the Interior for the approval of the fire extinguishers by the Ministry of Merchant Navy.
UNI 9492 defines a wheeled fire extinguisher a "fire extinguisher transported on wheels of a total mass greater than 20 kg and extinguishing content up to 150 kg"
DESCRIPTION OF FOAM WHEELDED FIRE EXTINGUISHERS
They consist on a chassis with two wheels and a handle for towing on which is installed the body of the fire extinguisher proper. The wheeled fire extinguisher is made up of a cylindrical or spherical metallic pressure receptacle, in which the extinguishing agent is contained, and the dispensing devices which are substantially similar to those for portable fire extinguishers.
The wheels of the trolley can be small, medium and large depending on the size of the extinguisher and the type of terrain on which it is to be moved.
The foam extinguisher consists of a steel sheet tank, treated against corrosion, whose charge is made up of foaming liquid diluted in water as a percentage that goes from 3 to 10%.
The pressurisation of the foam-mounted fire extinguisher can be permanently or can be done at the time of use, thanks to a baby doll of CO2 placed under the orifice of the fire extinguisher that in the case of necessity will be freed through its Drilling by a firing pin on the valve group.
The foam-wheeled fire extinguisher can be used on Class A-B outbreaks, which is mainly used in the naval sector.
It is not usable on electrical panels, class D outbreaks, chemical dust reagents with water.
The extinguishing device is made up of a pipe to which the end is connected a hand in anticorrosion material, at the base of which there are air inlet holes. At the start of the fire extinguisher and at the contemporaneous exit of the solution of foaming liquid, from the holes placed at the base from the Lance will enter air for venturi effect that mixing with the liquid in passing produces the foam that is directed on Fire principle.
