FR2718038A1 - Device for injecting and dosing a product in a water pipe for the fight against fire. - Google Patents

Abstract

A reservoir (7) contains the liquid additive, e.g. an emulsifier or wetting agent, connected by a suction pipe (8) to a recycling tank (10). A volumetric pump (5) draws additive from the tank to a motorised regulator valve (12,26). This has a first port piped (14) to an injector (16) in the water pipe (1), downstream from the fire pump (2). A return pipe (13) connects the valve second port to the tank. Flow meters in the additive (15) and water (17) pipes, upstream of the injector, supply information (d,D) to an electronic controller (21). This controls the regulating valve, depending on mixture data (C) input. The injector (18), inserted parallel to the water pipe axis, is closed or opened by a front piston (19) and return spring (20), depending on fluid pressure.

Description

The present invention relates to a device for injecting and dosing a

liquid additive product in

  a water pipe for fire fighting, this device for mixing the additive product with water5 flowing in a pipe, respecting a predefined proportion.

  Fire fighting often requires the use of additives to water, to improve the extinguishing power of the latter. Additives can be emulsifying, retarding, wetting, ... In all cases, they are dosed with water, with a percentage defined for each of them to ensure their effectiveness. There are several devices for the determination of additive products with water, which can be classified into two broad categories: firstly, the devices related to the additive product reserve, and secondly, the devices related to the fire pump,

therefore at the water point.

  As regards the mixing of the additive product with water, the most used means currently apply the principle of "venturi", and thus allow to incorporate the additive product to the water column by taking advantage of the speed of flow of the fluid. This device is located near the supply of additive product, and its main disadvantages are: - It is the cause of significant pressure losses

(up to 30%).

  - The concentration of additive product in the water is not adjustable and / or remains inaccurate (inaccuracy

greater than 10%).

  - Flow and pressure conditions are fixed. - The conditions of implantation of the device are

they are also fixed.

  Among the newly developed devices, many are mounted on a firefighting vehicle, near the fire pump putting the water into

movement and pressure.

  Thus, the French patent application N 2675697 describes a device for adding and mixing in a constant proportion of an additive in a main product, mounted on a fire extinguishing device. This mechanical mixing device reduces the useful power of the pump, it uses the principle of "venturi" (with the inaccuracies related to it), and especially it has the disadvantage of passing the product of addition with

the water in the fire pump.

  Advances in the field of electronics have made it possible to improve vehicle-mounted mixing devices. Thus, the European patent application N 0343320 discloses an installation comprising an automatic mixing device, electronically regulated with specific functions. If this device makes it possible to regulate automatically and suitably the addition and the mixing with water of an additive product, it always has the disadvantage of passing the product with the water in

the fire pump.

  The French utility certificate N 2598922 describes a mobile station for the manufacture of liquid retarding solutions. The device in question consists of a fire pump, two electromagnetic flowmeters and a volumetric pump for the additive product (retardant), which injects this product into the water pipe. The disadvantages of this device reside in the use of a hydrostatic transmission, linking the retardant pump to the fire pump, and the complexity of regulation. Indeed, the device uses two separate control chains, one for dosing the retardant flow, and the other for regulating the pressure at the output of the volumetric pump additive product. In addition to its specific disadvantages, the latter device, like the previous ones, has the major disadvantage of being linked to the fire pump (by the hydrostatic transmission). Overall, all these known devices for mixing a product additive to water, arranged on vehicles, therefore fix the replenishment at the water point, which removes all autonomy and flexibility of use . In addition, they are expensive because they require the purchase of a specially equipped firefighting vehicle, possibly plus the cost of electrical regulation.

unnecessarily complex.

  The present invention aims to solve the problems mentioned above, by proposing an autonomous device positioned near the supply of additive product but independent of the fire pump, thus endowed with a great flexibility of use, and using a simple electronic control reliable and at a reasonable cost, while ensuring a precise dosage and a homogeneous mixture of the adduct with the water, without

generate losses.

  For this purpose, the subject of the invention is essentially a device for injecting and dosing a liquid additive product into a water pipe for fire fighting which comprises, in combination: - a suction pipe connecting a reserve of adduct to a recycling tank of this product, - a positive displacement pump sucking the adduct into the recycling tank and sending it to a motorized regulating valve, - a pipe connecting a first channel of outlet of the motorized control valve to an injector placed in the water line downstream of the fire pump, - a return line connecting a second outlet of the motorized regulating valve to the tank for recycling the adduct a first flowmeter inserted on the additive product line connecting the regulating valve to the injector, and a second flowmeter placed in the water line upstream of the injector, and a regulating block Electronic receiving rate information from two flow meters, as well as a setpoint value representative of the proportion of additive product and water desired in the mixture, the control unit driving the motorized control valve. Thus, the proposed device can fit freely downstream of the fire pump (which is not traversed by the adduct), therefore between the vehicle pumping water and the fire hose, this which allows to position it at the o

  Additive product supply is the easiest.

  The device therefore has the major advantage of being able to fit into the existing operational schemas, and thus adapting to the equipment in place, which makes it possible to obtain a complete system with a high performance.

reasonable investment.

  As for the actual dosage, the use of a motorized regulating valve, combined with an electronic control unit, according to a simple operating scheme, makes it possible to precisely regulate the flow rate of injected addition product as a function of the proportion programmed, expressible in particular in the form

a percentage guideline.

  According to a preferred embodiment of the invention, the injector supplied with the addition product by the positive displacement pump is constituted by a pipe element disposed in the water pipe parallel to the axis thereof, a piston movable subject to the effect of a return spring being provided so as to shut off or release, depending on the fluid pressure, the front outlet of said pipe element. The movable piston advantageously has a conical shape, so as to act as a diffuser in the open position. Thanks to such an injector, arranged tangentially to the water stream and provided with a kind of diffuser, the product mixture with water is carried out without loss of load for the water pipe, and very homogeneously. In addition, the structure of the injector imposes a minimum pressure to introduce the adduct into the water pipe, which avoids waste of this product and allows the pump to operate in closed circuit (recycling of all the flow rate of additive product). Regarding recycling, although the principle is generally known, it will be noted that the present invention proposes an original and advantageous technical solution, by providing a recycling tank separate from the stock of product. additive, ce20 which makes it possible to operate in a closed circuit while avoiding a return to the supply of additive product. In an improved embodiment, the recycle tank is divided into two compartments, communicating with each other in a limited manner, by at least one internal turbulence partition, the return pipe from the motorized regulating valve. to one of the compartments, while the other compartment has at its lower part the connection of the pipe coming from the reserve of product of addition, and at its upper part the departure of

  the suction line supplying the positive displacement pump.

  In any case, the invention will be better understood

  using the following description, with reference to the unique

  Figure of the attached schematic drawing showing, by way of example, an embodiment of this device for injecting and dosing a product in a water pipe for fire fighting. This single figure illustrates, in a schematic form, the principle of production and operation of a device for injecting and dosing a liquid adduct, such as an emulsifier, into a water pipe 1. The water passing through the pipe 1 is set in motion and in pressure in this pipe 1 by a pump 2 (fire pump) situated upstream of the entire injection and dosing device, designated as a whole by the reference numeral 3 Downstream of this device 3, the mixture of water and additive, such as emulsifier, is directed towards a user device 4, such as a fire hose. The injection and metering device 3 comprises a positive displacement pump 5 driven by a motor 6. The adduct is stored in a tank 7. A suction pipe 8 comprising a check valve 9 connects the bottom of the tank 7 at the bottom of a recycling tank 10. A line 11, starting from the upper part of the recycling tank 10, leads to the suction port of the displacement pump 5. The output of this positive displacement pump 5 feeds a motorized regulating valve 12, an outlet channel of which is connected via a return line 13 to the tank of

recycling 10.

  The other outlet path of the regulating valve 12 constitutes the starting point of a pipe 14, on

  which is intercalated an axial turbine flowmeter 15.

  Line 14 leads to an injector 16 disposed to

  inside the water pipe 1.

  Another turbine flowmeter 17 is placed in the water pipe 1 upstream of the injector 16, for measuring the flow of water sent by the pump 2. The injector 16 and the flowmeter 17 are fixed on a tube - support that can be easily inserted into the water pipe 1 thanks

to appropriate connections.

  The injector 16 itself consists of a fixed tubular pipe 18 arranged parallel to the axis of the water pipe 1, a conical-shaped movable piston 19 adapted to close the front outlet of the pipe 18, and a return spring 20 placed at the rear of the injector 16 and acting on the rod of the piston 19 in the direction of the closure of the pipe 18. The injection of the additive product takes place when the pressure of this additive product, brought by line 14,

  is sufficient to take off the piston 19 from its seat. The conical shape of this piston 19 allows, in the open position, a better diffusion of the additive product in the water, so a good mixture of water with this additive product.

  The flowmeter 15 mounted on the pipe 14 traversed by the additive product, and the other flowmeter 17 placed in the water pipe 1, are electrically connected to an electronic control unit 21, by respective links 22 and 23 which convey the additive product flow rate information d and water flow rate D, respectively. The housing 21 has an inlet 24 for the introduction of a percentage setpoint C programmed by the operator, and an outlet 25 for the control of the electric motor 26 of the regulating valve 12. It will be noted that the recycling tank 10 is divided into two separate compartments 27 and 28, communicating with each other in a limited manner, by one or more internal turbulence partitions 29. One of the compartments 27, in which the conduct of

  return 13, is reserved for the recycling of the adduct.

  The other compartment 28 comprises at its lower part the admission of the adduct, arriving via the pipe 8 from the tank 7, and at its upper part the departure of the pipe 11 directing said product to

  the suction port of the positive displacement pump 5.

  The overall operation of the injection and metering device 3 is as follows: In case of a demand for a mixture of water and additive product, the fire pump 2 and the positive displacement pump 5 function simultaneously, each providing a certain flow rate, and the motorized regulating valve 12 calibrates the return flow of the additive product, brought back through the return line 13 to the recycling tank 10. The electronic means, contained in the regulation box 21, calculate at each instant the percentage expressing the ratio between the additive product flow d given by the flowmeter 15, and the water flow D given by the flowmeter 17, and compare this calculated percentage with the percentage setpoint C programmed by the operator. According to the result of the comparison, these electronic means drive the motorized valve 12, by sending to its motor 26 more or less long electric control pulses, negative or positive, depending on the difference between the actual percentage determined by measurement and calculation. , and the programmed percentage. If the actual percentage is lower than that programmed, the motorized valve 12 is actuated so as to further close the outlet channel opening into the return line 13, and to correspondingly increase the rate of additive product.

  sent via the line 14 to the injector 16.

  Conversely, if the actual percentage is greater than the programmed percentage, the motorized valve 12 is actuated so as to further open the outlet channel opening into the return line 13, and to correspondingly reduce the rate of additive product sent by line 14 to the injector 17. The motorized valve 12 can close or completely open the passage of the product

  addition to the return duct 13.

  Thanks to the movable piston 19 of the injector 17, subjected to the effect of the return spring 20, a minimum pressure is necessary to introduce a fluid into the water pipe 1. This allows to operate the positive displacement pump 5 in circuit closed, when in the rest position. Without these provisions, even when the motor valve 12 fully opens the way giving access to the return line 13, nothing would prevent the adduct from entering the water pipe 1,

  especially when it is not under pressure.

  The regulation system, operating in electric closed loop, thus makes it possible, irrespective of the flow rate or the water pressure in line 1, to inject into the latter an additive product with a concentration

  precise, without the operator having to intervene.

  It will be noted that the recycling tank 10 plays an important role for the regulation, because it makes it possible to operate in closed hydraulic circuit, so as to: - avoid a return of additive product in the tank 7, recycle this product variably, d a zero flow rate up to the maximum flow rate of the pump 5; - to avoid the disturbances at the suction of the pump 5, thanks to the anti-turbulence partitions 29 placed inside this tank 10; - to allow a prolonged operation of the device 3 in closed circuit, without there being

heating the product.

  All control parameters, or those relating to the flow meters 15 and 17, are programmable from a keyboard (not shown). The main functions of the regulation box 21 are, in turn, programmed during the manufacture of the device, from a standard regulation card. The regulation box 21 can be equipped to display the programmed percentage C ( defined above), as well as the actual percentage calculated from flow information d and D delivered by the flow meters 15 and 17. The value of the water flow through the pipe 1 can also be directly displayed. The housing 21 may also be equipped to perform other functions such as: totalization of flow rates, determination of the volume of adduct remaining in the tank 7 or indication of any other information,

according to user demand.

  From an electrical point of view, an alternator (not shown) mounted on the motor 6 is used to power a battery, constituting the energy source of the flowmeters and 17, the electronic control unit 21 and all the electrical equipment. Annex. These last features, combined with the arrangement of the assembly downstream of the fire pump 2, make this device 3 completely autonomous and allow its

  easy adaptation to pre-existing material.

  It goes without saying that the invention is not limited to the sole embodiment of this device for injecting and dosing a product in a water pipe for fire fighting which has been described here. above, as an example; it embraces, on the contrary, all variants of implementation and application respecting the same principle. It is thus, in particular, that the supply of additive product can be integrated into the device, or constituted by a tanker truck, or be made in the form of small compact containers, without it being possible to

  away from the spirit of the invention.

Claims (4)

  1. Device for injecting and dosing a liquid additive product, such as emulsifying, retarding, wetting, in a water pipe for the fight against fire, characterized in that it comprises, in combination: - a suction pipe (8) connecting a reserve (7) of adduct to a recycling tank (10) of this product, - a positive displacement pump (5) sucking the adduct into the recycling tank (10) and sending it to a motorized regulating valve (12,26), - a conduit (14) connecting a first outlet of the motorized regulating valve (12,26) to an injector (16) placed in the conduit of water (1) downstream of the fire pump (2), - a return line (13) connecting a second outlet of the motorized regulating valve (12,26) to the recycling tank (10) of the adduct, a first flowmeter (15) interposed on the adduct line (14) connecting the regulating valve (12,26) to the injector (16), thereby if a second flow meter (17) placed in the water pipe (1) upstream of the injector (16), and - an electronic control block (21) receiving the flow information (d, D) of two flow meters (15, 17), as well as a nominal value (C) representative of the proportion of additive product and water desired in the mixture, the control block (21)   driving the motorized regulating valve (12,26).   2. Device for injecting and dosing a product in a water pipe for fire fighting according to claim 1, characterized in that the injector (16) supplied with adduct by the pump volumetric device (5) is constituted by a pipe element (18) arranged in the water pipe (1) parallel to the axis thereof, a movable piston (19)   subjected to the effect of a return spring (20) being provided so as to close off or release, depending on the fluid pressure, the front outlet of said pipe element (18).   3. Device for injecting and dosing a product in a water pipe for the fight against   the fire according to claim 2, characterized in that the movable piston (19) has a conical shape, so as to act as a diffuser in the open position.   4. Device for injecting and dosing a product in a water pipe for the fight against   the fire according to any one of claims 1 to 3, characterized in that the recycling tank (10) is divided into two compartments (27,28), communicating one   with the other in a limited way, by at least one internal anti-turbulence partition (29), the return line (13) from the motorized regulating valve (12,26) leading to one of the compartments (27), while the other compartment (28) has at its lower part the connection of the pipe (8) from the supply of adduct (7), and at its upper part the start of the suction pipe ( 11)   supplying the positive displacement pump (5).