Fire extinguishers – Processes – Of extinguishing fire
Patent
1996-02-29
1998-04-14
Pike, Andrew C.
Fire extinguishers
Processes
Of extinguishing fire
169 9, 169 13, 169 62, A62C 310
Patent
active
057381747
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for fighting fire, in which method extinguishing liquid is delivered to at least one spray head, preferably a plurality of spray heads, by means of a drive unit comprising at least one hydraulic accumulator containing propellent gas chargeable up to a high initial pressure as well as a low-pressure water pump.
One advantage of using hydraulic accumulators in fire fighting equipments is a reduced dependence on availability of electric current for pump functions requiring energy. The problem is serious especially in ships and units comparable with them, in which the electric main system including the main generator is often put out of function in case of fires, and the emergency generator set, if existing, has an insufficient effect for practically whichever pump functions.
In case hydraulic accumulators are used, efficient fire fighting usually presupposes a high charging pressure, preferably up to 200 to 300 bar, in the hydraulic accumulators. For securing the function of the fire fighting equipment in an intended way, predetermined stages with relatively low driving pressure, e.g., 10 to 30 bar, should preferably also be included in the procedure, however. An example of such a stage is an initial cooling of the pipe system and especially the sprinklers or spray heads which before release have been heated by the fire broken out.
The object of the invention is to attend also to necessary low-pressure functions in a novel way by means of a high-pressure drive unit having one or several hydraulic accumulators, in order to achieve a minimum dependence on availability of electric energy.
The purpose of the invention is mainly that at least part of the propellent gas being left over after the hydraulic accumulators have been emptied of liquid is utilized for driving the low-pressure pump.
A preferred procedure is that at least part of the propellent gas being left over after the hydraulic accumulators have been emptied of liquid is utilized for driving the low-pressure pump, in order to refill the hydraulic accumulators with liquid and to spray simultaneously preferably the seat of fire and its surroundings with liquid and/or propellent gas so that the procedure can be repeated after the hydraulic accumulators have been filled.
Alternatively, it is in many cases of advantage that part of the propellent gas being left over after the hydraulic accumulators have been emptied of liquid is initially allowed to flow directly after the liquid to corresponding sprinklers and/or spray heads and that the remaining propellent gas is then utilized for driving the low-pressure pump, in order to refill the hydraulic accumulators with liquid and to spray simultaneously preferably the seat of fire and its surroundings with liquid and/or propellent gas so that the procedure can be repeated after the hydraulic accumulators have been filled.
According to a further-developed embodiment of the invention, the delivery of high-pressure liquid is delayed initially when the drive unit is switched on, during which delay stage gas is led preferably via a pressure reducing valve to drive the low-pressure pump for delivering cooling liquid to the pipe system and sprinklers and/or spray heads in question, and at least part of the propellent gas being left over after the hydraulic accumulators have been emptied of liquid is utilized for redriving (i.e., again driving) the low-pressure pump.
The delivery of high-pressure liquid is preferably delayed by leading the propellent gas from said at least one hydraulic accumulator to empty a liquid cylinder so that the liquid driven out of the cylinder affects, before passing a throttle, a spindle of a valve arranged in an outlet line of said at least one hydraulic accumulator in a direction closing the valve. Hereby the spindle surface affected by the pressure of said cylinder liquid is larger than the spindle surface affected by the outgoing liquid pressure of said at least one hydraulic accumulator, which pressure strives to open the valve, so that the valv
REFERENCES:
patent: 4224994 (1980-09-01), Tone et al.
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