JP2023519057A - CAFS system with improved air management system - Google Patents

Abstract

Compression comprising a compressor means (2), a mixing chamber module (4) and an air conditioning system (3) fluidly interposed in series between the compressor means (2) and the mixing chamber module (4) An air bubble fire suppression system or CAFS (1), an air conditioning system (3) comprising a plurality of sub-sections fluidly interposed in parallel with each other between a compressor means (2) and a mixing chamber module (4). Equipped with dosing modules (10), each dispense module (10) dimensioned to allow passage of a predetermined flow of compressed air to the mixing chamber module, the predetermined flow of one dispense module (10) being It differs from the default flow of other dispensing modules (10).

Description

(Cross reference to related applications)
This patent application claims priority from Italian Patent Application No. 102019000023679, filed December 11, 2019, the entire disclosure of which is incorporated herein by reference.

The present invention relates to fire suppression systems for firefighting vehicles or installations, particularly compressed air foam fire suppression systems (CAFS) with improved air management systems.

Firefighting systems, such as firefighting vehicles or equipment, include firefighting systems that are configured to deliver a fire extinguishing compound that is directed at the flame to cause the fire to be extinguished.

In particular, compressed air foam fire-fighting systems (CAFS) are widely known in the art and involve the use of a mixture of compressed air and water/foaming agent solution in preset proportions.

More specifically, the water-blowing agent solution contains the blowing agent additive dissolved in a large amount of water, ie from 0.5 to 3%, or up to 8% by volume of the additive. Compressed air is mixed with such solutions in the mixing chamber module.

Such an air-solution mixture, at superatmospheric pressure, is expelled by the outlet of the pipe directed at the flame, and as it expands it forms a foam with flame-extinguishing properties. In particular, the air content of the foam can be adjusted to take a value between 3 and 20 air volume parts for the liquid solution. Such air/solution ratios comprised between 3 and 10 are defined as "wet foam", as defined in DIN EN standard 16327, whereas air comprised between 11 and 20 /solution ratio is defined as "dry foam".

Due to the above, a major challenge with CAFS systems is to continuously measure the air and water streams that are mixed together to provide the desired air/solution ratio. Therefore, the measurement of these two flows is critical.

Measuring water flow is substantially straightforward, but measuring air flow over between 3000 and 6000 liters/minute is less straightforward.

A first approach to measuring airflow is to use a conventional airflow meter. However, since water and other particles carried by the airflow can adhere to the sensor and interfere with the amperometric signal, thereby slightly or completely altering the measured airflow, the airflow meter is not sensitive to air concentration. very susceptible.

A solution to the above problem has been found in that an air dryer can be placed upstream in the direction of flow of the compressor intended to provide the compressed air flow in order to condense the moisture present in the air drawn by the compressor. has been served. However, due to the required airflow values described above, such air dryers would have dimensions that would render them unusable in firefighting mobiles/vehicles.

Another known solution for measuring airflow is to use mass airflow sensors, which are well known in the engine field. In fact, for normal operating fields the air flow velocity is so low that air does not condense at the sensor due to the low pressure drop.

However, the airflow can be continuously varied since the flow of the air/solution mixture can be continuously changed by the operator depending on the flame conditions. Such variations in airflow values lead to variations in the mass airflow sensor, thereby adding vibration and noise to the system.

Another alternative solution would be to provide a valve configured to have a working range of 40-4800 liters/minute. However, such valves are extremely expensive to manufacture and uncommon on the market.

Due to the above, there still remains the problem of measuring and ensuring proper compressed air flow for CAFS systems.

Therefore, a need is felt to provide a CAFS system capable of rapid and precise adjustment of the air-solution mixture according to user demand.

SUMMARY OF THE INVENTION It is an object of the present invention to meet the above needs in a cost-effective and optimal manner.

The above objects are achieved by a compressed air foam fire extinguishing system according to the attached series of claims.

For a better understanding of the invention, preferred embodiments will now be described, by way of non-limiting example, with reference to the accompanying drawings.
1 is a schematic representation of the innovative portion of a compressed air foam fire extinguishing system according to the present invention; 1 is a schematic representation of possible combinations for providing the elements of a compressed air foam fire extinguishing system according to the present invention; 1 is a schematic representation of a compressed air foam fire extinguishing system according to the invention;

FIG. 1 discloses a compressed air foam fire extinguishing system or CAFS 1 essentially comprising a compressor means 2 , an air conditioning system 3 and a mixing chamber module 4 . In particular, the compressor means 2 are fluidly connected in series with the air conditioning system 3 which is fluidly connected in series with the mixing chamber module 4 .

More specifically, the compressor means 2 is arranged to increase the pressure of air, eg atmospheric air, taken from a suitable source 5 by an air filter between the inlet 2a and the outlet 2b of the compressor means 2 . As is well known, the compressor means 2 can be of any topology depending on the power requirements of the CAFS 1.

From the opposite side of the air conditioning system 3, the mixing chamber module 4 has a first inlet 4a fluidly connected to the air conditioning system 3 and a second inlet 4a of known topology fluidly connected to a source 6 of foam solution. Schematically and essentially, it comprises two inlets 4b and an output 4c fluidly connected to a fire extinguishing arrangement 7 arranged to allow discharge of foam mixed in the mixing chamber module 4 . It is clear that such a fire extinguishing installation 7 can be of any topology, for example a pipe with a dedicated nozzle at its end.

fluidly interposed between the compressor means 2 and the air conditioning system 3 for discharging compressed air delivered by the compressor means 2 to the air conditioning system 3 when the pressure of the compressed air reaches a predetermined value; Advantageously, the CAFS 1 comprises safety means 8 arranged to allow

Preferably, such a safety means 8 is fluidly connected downstream of the output 2b and upstream of the air conditioning system 3 when the pressure in the air conditioning system 3 reaches a threshold, for example about 11 or 12 bar. Equipped with a pressure relief valve 9 adapted to open when necessary to allow discharge of the air conditioning system 3, the pressure of the compressed air being typically 10 bar.

Safety measures also allow the value of the pressure provided by the compressor means 2 to the air conditioning system 3 to be kept stable to avoid pressure peaks.

The air conditioning system 3 comprises according to the invention a plurality of dispensing modules 10 interposed fluidly in parallel between the output 2b of the compression means 2 and the mixing chamber module 4, each dispensing module The modules are configured to be controlled to allow the passage of air from the compression means 2 to the mixing chamber module 4 and are configured to allow the passage of a predetermined flow different from at least another dispensing module 10. .

In the exemplary embodiment, seven different dispensing modules 10 are fluidly interposed in parallel between the compression means 2 and the mixing chamber module 4 .

Each dispensing module 10 comprises a valve means 11 and a nozzle 12 fluidly in series with each other, one with respect to the other, the valve means 11 being upstream of the respective nozzle 12 to allow the compressor means 2 to flow from the nozzle 12 . allow or deny passage of air to Each nozzle 12 is then directly fluidly connected to the mixing chamber module 4 .

According to a further aspect of the invention, the first dispense module 10 has a first base flow rate value and the other dispense modules are at least N times the first base flow rate value (where N is preferably an integer). It has various flow rate values. Preferably, the other dispensing modules may each have a flow rate value that is double that of the preceding module.

Thus, in the disclosed embodiment, the seven dispense modules 10 allow adjustment of the flow rate by ²⁷ or 128 possible values for controlling the flow rate at the input to the mixing chamber module 4 .

Preferably, the first dispensing module is sized to allow a flow rate of 50 liters/minute, the second at 100 liters/minute, the third at 200 liters/minute and the fourth at 400 liters/minute as described above. , the fifth is 800 l/min, the sixth is 1600 l/min and the seventh is 3200 l/min.

Furthermore, according to DIN EN 16327, the solution flow should be comprised between 200 and 1600 l/min and the air flow should be at least three times higher, ie between 600 and 4800. According to the proposed embodiment, the theoretical maximum is 6350 liters/minute, so an air range of 600-4800 liters/minute can be readily provided.

Since the pressure is also kept constant at the output of the compressor means 2 by the pressure relief valve 9, the flows of each dispensing module 10 merge into the mixing chamber module 10, which provides the desired air flow rate and accuracy. is set by the minimum flow dispense module.

In fact, by opening more valve means 11 simultaneously, the flows passing through the different nozzles 12 are merged. According to the values given above, by adjusting the opening of the valve means 11, 50, 100, 150 [. . . ]from[. . . ] 6250, 6300, 6350 streams may be provided.

According to a further aspect of the invention, each nozzle 12 may be embodied by joining together a specified number of low flow nozzles. Indeed, the 100 liter/min nozzle consists of two 50 liter/min bores and the 3200 liter/min nozzle consists of eight nozzles, as shown in FIG. 2 where possible nozzle bore sets are marked. 400 l/min bore of Therefore, as diagrammatically shown, the entire possible range of flow rates can easily be achieved with only two bores.

The CAFS 1 further comprises a control unit 13 connected to the mixing chamber module fire extinguishing system 7 , to the water flow sensor and to each valve means 11 . Such a control unit 13 is arranged to control the opening or closing of each valve means 11 according to signals emitted by the fire extinguishing installation 7 and/or the mixing chamber module 4 .

Such a control unit 13 is an electronic control unit and therefore the valve means 11 is an electrically actuated valve, the above-mentioned signal being the mixing chamber module 4 (i.e. the mixing chamber module, the water provided in the mixing chamber module 4). /solution flow) and a signal provided by a sensor arranged to provide an estimate of the relevant quantity from the fire extinguishing equipment 7, for example the air/foam solution flow rate selected by the operator.

In practice, the operator selects the desired air bubble solution, for example by pressing a button or by making a selection on a particular display, and maintains the open or closed state to achieve such values. A control unit 13 is arranged to consider the combination of valve means 11 that must be present. Therefore, in order to select the proper opening/closing combination of the valve means 11, the control unit 13 stores or has access to the memory in which this is stored the value of the flow rate for each particular dispensing module of the air conditioning system 3. should be provided. Preferably, each value of desired air flow rate in the mixing chamber module 4 can be stored with the associated opening/closing combination of the associated valve means 11 .

FIG. 3 discloses a more complete scheme for a possible embodiment of all elements of CAFS1.

In particular, the compressor means 2 comprise in parallel another compressor means 2' arranged to supply another compressed air flow, for example in the case of small dimensions of such compressor means 2, 2'. It is clear that each compressor means 2, 2' can be provided with a respective check valve 20, 20'.

The air conditioning system 3 comprises, in the illustrated case, eight dispensing modules 10, each comprising a valve 11 and a nozzle 12, as described in detail above. As noted above, air conditioning systems are configured to provide airflow rates from 50 to 3000 (and optionally up to 6000 or more).

The air conditioning system 3 may then be fluidly connected to the mixing chamber module 4 with associated check valves 21 and connected to the safety means 8 as described above, and may also be provided with pressure sensor means 26 .

In particular, the water supply to the mixing chamber module 4 is supplied by a vehicle water line fed by an associated pump 23 configured to increase the pressure of water taken from a supply source, for example a tank carried on the vehicle. Sent from 22.

In the conduit fluidly connecting the water supply line 22 and the mixing chamber module 4, the CAFS 1 also provides water to the mixing chamber module 4 when such water is required for other preemptive uses by the vehicle. an optional throttling stage 24 known per se and therefore not described in detail, adapted to thwart the water supply of the .

Furthermore, at any conduit fluidly connecting the water supply line 22 and the mixing chamber module 4 , the CAFS 1 comprises water flow meter means 25 arranged to measure the water flow rate into the mixing chamber module 4 . In particular, the water flow meter means 25 can measure water flow rates, for example between 0 and 3000 l/min.

Optionally, upstream and downstream of the suppression stage 3 the CAFS 1 may also comprise pressure sensor means 26 arranged to detect water pressure from the mixing chamber module 24 .

CAFS 1 further comprises an additive dispensing module 27 configured to provide a measured amount of additive to mixing chamber module 4 . Specifically and illustratively, the additive dispensing module 27 comprises an additive container 28 into which the additive is pumped into the mixing chamber module 4 by a pump 29 . In the conduit fluidly connecting the pump 29 to the mixing chamber module 4, the additive dispensing module 27 preferably has a safety means 8 with a relief valve 9 to maintain the pressure below a preset threshold, for example 16 bar. equip.

The additive dispensing module 27 is further provided in a conduit fluidly connecting the pump 29 and the mixing chamber module 4 , the CAFS 1 being configured to measure the additive flow rate from the mixing chamber module 4 . A physical flow meter means 30 is provided. In particular, the additive flow meter means 25 can measure water flow rates between 0 and 30-60 liters/minute.

Therefore, in the proposed embodiment, the mixing chamber module 4 is configured to mix water, additive and airflow together to provide an air/solution mixture to the fire extinguishing device 7 .

Therefore, the mixing chamber module 4 includes a first mixer 31 configured to mix together the water flow and the additive flow, and a first mixer 31 configured to mix together the water-additive solution and the air flow. and a second mixer 32 downstream of the first mixer 31 configured in order to produce the solution-air mixture discharged by the fire extinguishing device 7 . A water flow meter 25, an additive flow meter 25 and, if present, a pressure sensor 26 are all electrically connected to the electronic control unit so that proper air flow generation can be seen in the mixing chamber 4. .

The operation of CAFS1 according to the invention described above is as follows.

The operator of fire extinguishing device 7 selects a specific value for the air bubble flow rate. A specific signal (calculated by the electronic control unit as described above) is therefore provided to the control unit 13 which considers/selects the proper opening/closing combination of the valve means 11 .

By way of example, based on the exemplary values above, if the operator requires an airflow of 1350 to the mixing chamber module, then the first, second, fourth and fifth dispense modules 10 valve means allow passage of fluid to provide proper airflow values.

The control of water and additive streams is well known per se and will therefore not be described in detail. The electronic control unit 13 also controls the flow of water and solution to the mixing chamber module 4 accordingly, with operator confirmation of the flow and nature of the required air-solution mixture.

According to the above, the present invention further comprises:
- obtaining data relating to the airflow required in the mixing chamber module 4 of the CAFS 1;
- selecting a particular combination of valve means 11 for opening at least one dispensing module 10 that matches the airflow required in the mixing chamber module 4;
- activating the valve means 11 of at least one relevant dispensing module 10 selected in the previous item;
A method for providing a predetermined air flow rate to the mixing chamber module 4 of a CAFS system, including

Advantageously, the method described above is stored and executed by means of the electronic control unit 13 discussed above.

In view of the above, the advantages of the compressed air foam fire extinguishing system CAFS1 according to the invention are evident.

The proposed control is stable, robust, precise and can be implemented in an economical manner. In fact, since the pressure differential remains constant at the opening of the nozzle 12, its flow rate is easily determined and unaffected by fouling particles and moisture condensation. Additionally, the nozzle does not suffer from the vibration/noise problems of prior art systems and can be housed in a very small space. By way of example, a 400 l/min nozzle has a diameter of only 2-3 mm.

Further, the wear of such nozzles can be checked by cost effective means such as feeler gauges and therefore accuracy can be tested in time. Furthermore, since simple mechanical elements are used, CAFS1 is particularly robust and can be used in a wide variety of atmospheric conditions.

Since the system is very simple to use, i.e., no complex electronic controls are required, even untrained personnel can use the proposed CAFS1 fire extinguisher base.

In particular, the use of a 2×2 nozzle system with a substantially binary system can be controlled by very simple software, for example by stored tables defining binary sums between nozzles.

Moreover, since the proposed CAFS1 is immediate response, it overcomes the delay of slow control systems (to avoid vibrations).

Pressure relief valve 9 provides a defined inlet pressure upstream of nozzle 11 in a simple and robust manner.

It is clear that modifications can be made to the described compressed air foam fire extinguishing system CAFS1 which do not go beyond the scope of protection defined by the claims.

Firstly, the possible combinations of injection modules 10 described above are particularly advantageous due to their economical manufacturing. However, it is clear that any possible number of different injection modules 10 can be provided, encompassing different minimum flow rate values and different flow distributions therebetween. Indeed, such properties can be customized for a particular use of the fire suppression system 7.

As already mentioned, the valve means 11, the compressor means 2 and the fire fighting equipment 7 may vary depending on the topology of the fire fighting equipment/vehicle.

Furthermore, it is possible, even if less economical, to provide hydraulic or pneumatic control of the valve means 11 according to the claimed invention.

1 Compressed Air Foam Fire Extinguishing System (CAFS)
2, 2' Compressor Means 2a Input 2b Output 3 Air Conditioning System 4 Mixing Chamber Module 4a First Inlet 4b Second Inlet 4c Outlet 5 Source 6 Source 7 Fire Extinguishing System 8, 8' Safety Means 9 Pressure Relief Valve 10 Dispensing module 11 valve means 12 nozzle arrangement 13 control unit 20, 20', 21 check valve 22 vehicle water line 23 pump 24 suppression stage 25 water flow meter means 26 pressure sensor means 27 additive dispensing module 28 additive container 29 pump 30 Additive flow meter means 31 first mixer 32 second mixer

Claims (15)

Compressor means (2) for increasing the air pressure between the input section (2a) and the output section (2b), a water/additive solution supply source (6), the pressurized air and the water/additive A compressed air foam fire extinguishing system or CAFS (1) comprising a mixing chamber module (4) configured to provide an air-solution mixture consisting of:
said mixture is further fluidly connectable to a fire extinguishing system (7) arranged fluidly interposed in series between said output (2b) of said compressor means (2) and said mixing chamber module (4). a system further comprising: an air conditioning system (3) configured between said output (2b) of said compressor means (2) and said mixing chamber module (4); a plurality of dispense modules (10) fluidly interposed in parallel with each other, each dispense module (10) selectively allowing passage of a predetermined flow of compressed air to said mixing chamber module; wherein said plurality of dispense modules (10) are sized such that the default flow of one dispense module (10) is different than the default flow of another dispense module (10);
Compressed air foam fire extinguishing system. Each dispensing module (10) comprises a valve means (11) and a nozzle device (12), said valve means (11) being arranged upstream in series with said nozzle device (12), and said compressor means. configured to allow or deny passage of fluid from (12) to said nozzle arrangement (12), said nozzle arrangement (12) dimensioned to allow passage of a preset airflow at a predetermined pressure. The system of claim 1, wherein: 3. System according to claim 1 or 2, wherein the predetermined flow of the other dispensing module (10) is N times the flow of the one dispensing module (10). the number of pipetting modules is N, the predetermined flow of the (N)th pipetting module (10) is twice the predetermined flow of one (N-1)th pipetting module (10), and N 4. A system according to any preceding claim, wherein is an integer. further comprising safety means (8) fluidly interposed between said output (2b) of said compressor means (2) and said air conditioning system (3), said output (2b) and 5. A system according to any preceding claim, wherein the safety means (8) are arranged to discharge compressed air when the pressure between the air conditioning system (3) reaches a predetermined value. . 6. System according to claim 5, wherein the safety means (8) comprise a pressure relief valve (9). further comprising a control unit (13) configured to be connected to said fire extinguishing equipment (7) and to each valve means (11) from said extinguishing equipment (7) and/or said mixing chamber module ( 7. A system according to any of claims 2 to 6, wherein said control unit (13) is arranged to control the opening or closing of each valve means (11) depending on the signal emitted from 4). 8. A system according to claim 7, wherein said control unit (13) is an electronic control unit and said valve means (11) are electrically actuated valve means. Claims 2 to 8, wherein the nozzle arrangement (12) is embodied by a single nozzle with a defined flow dimension or by connecting together a plurality of said nozzles with a defined flow dimension in parallel. A system according to any one of the preceding claims. Said dispensing module (10) comprises a first dispensing module selectively allowing passage of an air flow of 50 liters/minute and a second dispensing module selectively allowing passage of an air flow of 100 liters/minute. a third dispense module selectively allowing 200 liters/minute airflow through; a fourth dispense module selectively allowing 400 liters/minute airflow through; a fifth dispense module selectively allowing 1600 liters/minute of airflow through; a sixth dispense module selectively allowing 1600 liters/minute of airflow through; 10. The system of any of claims 1-9, wherein seven of the seventh dispensing modules selectively allow for . Said mixing chamber module (4) comprises a first mixer (31) for providing a mixture of said pressurized air and said water-additive solution; , and a second mixer (32) downstream of said first mixer (31). A system according to any preceding claim, wherein said compressor means (2) comprises a plurality of compressors (2) parallel to each other. A fire fighting system comprising a system according to any of claims 1-12. A fire vehicle comprising a system according to any of claims 1-13. A method for providing a predetermined air flow rate to a mixing chamber module (4) of a compressed air foam fire extinguishing system or CAFS system according to claim 8, comprising:
- obtaining data relating to the airflow required in said mixing chamber module (4) of said system (1);
- selecting a particular combination of valve means (11) for opening at least one dispensing module (10) that matches the airflow required in said mixing chamber module (4);
- activating the valve means 11 of at least one relevant dispensing module (10) selected in the previous item;
A method that encompasses

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