EP0647458A1 - Device for mixing additives to a liquid - Google Patents

Abstract

The invention describes an admixing device (2) for admixing additives to a liquid (14), especially to a solvent, for example in fire-fighting vehicles (1). Arranged in a delivery conduit (18) for the liquid (14) is a measurement transducer (8) for the throughflow quantity in this delivery conduit (18). Connected to a supply conduit (41) of the delivery conduit (18) is a drive device (30) for a conveying device (27) which conveys the additive from an additive tank (5) into an admixing conduit (19). The throughflow quantity of the liquid (14) through the drive device (30) is regulated via a regulating device (52) in dependence on the liquid quantity flowing through the delivery conduit (18). The drive device (30) is motionally connected to the conveying device. The supply conduit (41) for the drive device (30, 132) branches off upstream of the measuring device in the direction of flow of the liquid (14). The regulating device (52, 152) is located downstream of the drive device (30, 132) in the direction of flow of the liquid (14). There is arranged a control and/or indicator device (7, 138) which has a measurement transducer (8) of the measuring device and an input member (24) for a quantity of additives which can be added to a predeterminable liquid quantity or a measuring apparatus (145) for detecting the fed quantity of additives. <IMAGE>

Description

The invention relates to an admixing device for admixing an additive to a liquid, in particular for admixing foaming agents in extinguishing agents, e.g. in fire fighting vehicles, as described in the preamble of claim 1, and a method for admixing additives to a liquid, in particular an extinguishing agent, as described in the preamble of claim 18.

A mixing device for adding an additive to a liquid is already known - in accordance with DE-AS 20 48 904. In this mixing device, an additive is fed from an additive container into a liquid supply line for sprinklers. For this purpose, part of the liquid or the extinguishing agent is removed between a liquid pump and the sprinklers and fed to a water motor which, via a coupling, acts on a peristaltic pump for mixing the additive into the liquid line. The regulation of the amount of the admixture to be admixed takes place by determining the delivery quantity of liquid in front of the removal point for the liquid for driving the water motor. Depending on the amount of liquid flowing past, the speed of the water motor is controlled so that a constant percentage of additive is added to the liquid. To change the speed of the water motor, the measuring device for the amount of liquid flowing through the delivery line is coupled via a differential gear to the output shaft of the water motor, with speed differences between the rotation of the measuring device generated by the flowing water through a helical propeller arranged in the delivery line and the Result speed from the water motor, cause a change in the passage cross-section of the liquid to the water motor until an equal speed or a predetermined speed ratio in the area of the rotary differential gear is reached. The disadvantage of this solution is that the amount of admixed additive is relatively imprecise and, moreover, the admixing ratio, that is, the proportion of additive that is to be admixed to a predetermined amount of liquid, cannot be adjusted.

Furthermore, an admixing device is also already known - according to DE-OS 30 38 334-, in which extinguishing agent outlets can optionally be charged with liquid or with a mixture of liquid and additive. For this purpose, it is provided that additive is drawn in from an additive tank via a pump with a controllable drive motor and as a function of the delivery rate in the delivery line, which leads to the extinguishing agent outlets, which are mixed with a mixture of liquid and foam agent are to be loaded, and depending on an admixing amount of additives for a predefined amount of liquid, a higher pressure is pressed into the liquid line in front of the extinguishing agent outlets. The disadvantage here is that a separate energy source and a separate drive system is required to drive the metering device. Furthermore, monitoring the further metering of the additive is extremely difficult and usually requires extensive additional measuring devices, the adaptation of which to the different additives, in particular the different viscosities of the additives, is difficult.

It is therefore an object of the invention to provide an admixing device in which, with a freely selectable ratio between the amount of liquid and the amount of additive, a constant constant exact admixture of the required amount of additive into the conveying means is achieved even over a long period of operation.

This object of the invention is achieved by the features in the characterizing part of claim 1. The advantage of this solution is that due to the surprisingly simple solution, the amount of additive required for different admixing rates is supplied via the amount of liquid passed through the drive device, depending on the flow rate of the mixture required at the extinguishing agent outlets or the extinguishing agent thrower. In addition, the liquid required for the drive device is removed before the flow rate is determined, so that the accuracy of the admixed amount of admixture is exactly maintained, even with a high liquid throughput for driving the drive device. However, this enables the admixing device to be used in a surprisingly simple manner for the most diverse additives with different viscosities and admixing rates. In addition, the amount of liquid required to drive the tank can be supplied to the suction inlet of the extinguishing agent pump, in particular in the case of tank fire-fighting vehicles, and consequently there is no loss of liquid or, in the case of non-environmentally compatible extinguishing agents, environmental pollution can be prevented. In addition, the formation of the admixing device ensures an almost continuous flow of the additive into the extinguishing agent. In addition, there is almost no delivery loss at those extinguishing agent outlets to which a mixture of extinguishing agent and additive is dispensed, since the amount of extinguishing agent required to drive the drive device essentially corresponds to the amount of additive supplied before the extinguishing agent outlets.

By training according to claim 2, exact regulation of the admixed amount of admixture is achieved due to the rapid readjustment possibility.

Another advantage of the embodiment variant according to claim 3 is that in the area of the additive supply between the conveying device and the admixing line, no measuring element for the flow rate of the additive is required. In this way, malfunctions during the transport of the admixture as well as flow resistance can be avoided and thus a perfect admixture of very tough admixtures is also possible.

Through the further training according to claim 3, a fully automatic control of the admixed amount of admixture is achieved.

An embodiment variant according to claim 4 is also advantageous, since the excess pressure with which the additive is pressed into the admixture line is simply determined by determining the volume ratios between the drive device and the conveying device, and the losses resulting from the viscosity and the mechanical transmission are also eliminated can be, so that regardless of the pressure conditions in the admixture line in proportionally dependent, the additive is fed into the admixture line with overpressure.

However, an embodiment according to claim 5 is also advantageous, as a result of which the admixing device can be produced with a single component, namely a cylinder-piston unit with two coupled pistons.

Furthermore, an embodiment variant according to claim 6 is also possible, whereby a compact structural unit is created which can be used with little expenditure on mechanical adjusting elements for controlling or regulating the individual functions of the drive and conveying device.

However, a further development according to claim 7 is also possible, as a result of which, with a junction in the distributor plate, the foaming agent is alternately forwarded to the different cylinder chambers and, at the same time, the additive can also be discharged into a common line.

By arranging the check valves according to claim 8 is easier A self-control of the suction and pumping action is achieved with the cylinder forming the conveying device.

An embodiment according to claim 9 is also advantageous, since this allows the pressure differences between the liquids conveyed with the extinguishing agent pump and a higher pressure in the pressure line of the additive or foam agent to be achieved in a simple manner. A pressure difference can thus preferably be defined, which at least compensates for the frictional losses which occur in the course of conveying the foam agent or the additive from the foam agent tank to the admixture line. It is also advantageous if this pressure difference is chosen to be larger, since it enables uniform, continuous pressing of the foam or additive into the mixing line.

The embodiment variant according to claim 10 enables the use of the advantages according to the invention also in connection with rotating conveying or drive devices, since freestanding operation of the admixing device is possible without separate fastening, especially with larger conveying quantities.

For higher outputs, however, a further embodiment variant according to claim 11 is also recommended.

Especially when using rotating drive or conveyor devices, the training according to claim 12 is recommended, since this allows greater pressure increases to be achieved in a narrow space.

Due to the further embodiment according to claim 13, it is possible to provide manual control in addition to the automatic control, at least for emergency operation, so that, as is very important in emergency vehicles, the production of a foam liquid mixture is possible under any operating situation.

By utilizing pressure medium devices, a mechanical display of the admixing ratio can also be achieved in a simple manner according to the features in claim 14 without complex electronic control and regulating devices.

A further development according to claim 15 is also advantageous, since this enables rapid reversing and also a high stroke frequency of the admixing device is.

However, an embodiment according to claim 16 is also advantageous, since in this way the operating situations that change constantly due to changes in viscosity or the like can be monitored with each stroke and thus reacted very sensitively to any changes, so that the desired admixing ratio is maintained evenly.

Another embodiment variant is described in claim 17. It is advantageous that, by forming a transportable unit, the admixing device at any location in mobile operation, regardless of a permanently installed pump system, also in connection with a wide variety of pumps, e.g. Portable syringes or stem pumps or the like can be used in the fire service. This also makes it possible to use the advantages of this admixing device in those areas in which it is not possible to access heavy fire trucks in which such admixing devices are arranged in a stationary manner.

The invention also includes a method for admixing additives to a liquid, in particular an extinguishing agent, as described in the preamble of claim 18.

This method is characterized by the measures in the characterizing part of claim 18. It is advantageous here that only the amount of liquid that is actually supplied to the extinguishing agent outlets to which the mixture of extinguishing agent and additive is applied is used to regulate the amount of additive to be mixed. The further advantage of these surprisingly simple measures lies in the fact that with the existing pressure medium, namely with the extinguishing agent or a part thereof, the foam agent can be injected or metered into the extinguishing agent under a higher pressure than the extinguishing agent, so that thorough mixing and an exact retention of the admixing rate or the proportion of foaming agent to the extinguishing agent can be achieved.

Finally, a procedure according to claim 19 is also advantageous, since the constant monitoring of the rotational or lifting speed of the drive device enables sensitive regulation and continuous adjustment of the delivery rate of the additive to be added, which in particular when using foam agent results in a uniform foam build-up with the same high quality and corresponding foaming volume and thus a very favorable use of the extinguishing agent and additive can be achieved.

At the same time, it is ensured by the procedure according to claim 20 that that amount of extinguishing agent that is required to operate the admixing device, i.e. to drive the conveying device, is not lost, but rather in the circuit by being fed into the suction line of the extinguishing agent pump or being returned to an extinguishing agent tank can be used again and thus there is no loss of extinguishing agent or the extinguishing agent requirement is not increased by the function of the admixing device.

For a better understanding of the invention, it is explained in more detail below with reference to the exemplary embodiments shown in the drawings.

Fig. 1

eine erfindungsgemäße Zumischeinrichtung zum Herstellen von insbesondere schaumförmigem Löschmittel in einem Feuerwehrfahrzeug in Seitenansicht;

Fig. 2

ein schematisches Blockschaltbild einer Zumischeinrichtung zum Herstellen von insbesondere schaumförmigem Löschmittel unter Verwendung der erfindungsgemäßen Dosiervorrichtung;

Fig. 3

eine erfindungsgemäße Dosiervorrichtung in Stirnansicht;

Fig. 4

die erfindungsgemäße Dosiervorrichtung in Seitenansicht, geschnitten, gemäß den Linien IV-IV in Fig. 3;

Fig. 5

die erfindungsgemäße Dosiervorrichtung in Draufsicht, teilweise geschnitten dargestellt;

Fig. 6

eine Ausführungsvariante der erfindungsgemäßen Zumischeinrichtung unter Verwendung einer rotationsbewegten Antriebsvorrichtung bzw. Dosiervorrichtung in vereinfachter, schematischer Darstellung;

Fig. 7

eine Ausführungsform der Steuereinrichtung für manuelle Regelung zur Einhaltung des Zumischverhältnisses einer Zumischmenge an Zusatzmittel für eine vordefinierte Menge an Flüssigkeit in vereinfachter, schematischer Darstellung.

Show it:

Fig. 1

an admixing device according to the invention for producing foam-like extinguishing agent in a fire engine in side view;

Fig. 2

a schematic block diagram of an admixing device for producing in particular foam-shaped extinguishing agent using the dosing device according to the invention;

Fig. 3

a metering device according to the invention in front view;

Fig. 4

the metering device according to the invention in side view, sectioned, along the lines IV-IV in Fig. 3;

Fig. 5

the metering device according to the invention in plan view, shown partially in section;

Fig. 6

a variant of the admixing device according to the invention using a rotationally moving drive device or dosing device in a simplified, schematic representation;

Fig. 7

an embodiment of the control device for manual control to maintain the admixing ratio of an admixing amount of additives for a predefined amount of liquid in a simplified, schematic representation.

1 shows a fire engine 1, in particular a tank fire-fighting vehicle, which is equipped with an admixing device 2 according to the invention for producing foam-like extinguishing agent, in particular water, mixed with additives, in particular foaming agents or plasticizers.

This admixing device 2 consists essentially of an extinguishing agent tank 3, an extinguishing agent pump 4, an additive tank 5, a metering device 6 for additive, a control and / or display device 7 and a measuring device with a transmitter 8 for determining the flow rate of the amount of extinguishing agent to be mixed with the additive . In connection with the admixing device 2 there are also an extinguishing agent launcher 9, as well as a group 10 of extinguishing agent outlets 11 and a group 12 of extinguishing agent outlets 13.

The arrangement of the admixing device 2 is shown in a simplified and partially schematically illustrated manner.

The extinguishing agent pump 4 and the extinguishing agent tank 3 are adjacent to extinguishing and / or recovery equipment, such as fittings, hoses, cutters or the like. The respective loading of a fire-fighting vehicle 1 equipped with such an admixing device is arbitrary and can be adapted to the respective application. For example, fire engines used at airports are mostly equipped with tanks and extinguishing agents and additives and contain only small amounts of equipment, while in the case of universal fire fighting vehicles in residential areas, the combined vehicles with tanks up to 2000 to 4000 l extinguishing agent, especially water and the like large additive tanks and equipment for rescue and recovery, such as hydraulic cutting and spreading devices as well as light generators, hoses and extinguishing fittings predominate.

Of course, this admixing device 2 can also be used for emergency vehicles used in other areas, for example in the road maintenance service or for cleaning work in which, for example, liquids with cleaning additives, Plasticizers, various gases such as tear gas or irritant liquids are added.

FIG. 2 shows the arrangement of the admixing device 2 for producing additives, in particular foaming agents or plasticizers offset by foam-like extinguishing agents, schematically in a block diagram.

An extinguishing agent tank 3 contains a liquid 14, preferably water, and is connected to the extinguishing agent pump 4 via a tank outlet line 15, a shut-off valve 16 and a suction line 17. The sensor 8 for determining the flow rate is arranged between a pressure line 18 of the extinguishing agent pump 4 and a mixing line 19. The sensor 8 is also connected to the control and / or display device 7 via a line 20.

The control and / or display device 7 is composed of a comparator 21 for the flow rate of the amount of extinguishing agent to be mixed with the additive and the admixing factor over a fraction of additive to be added to a predeterminable amount of liquid 14, and a comparator 22 for monitoring the stroke frequency of the metering device 6 and a setpoint memory 23. The admixing factor, for example in percent, for the setpoint memory 23 can be preset via an input element 24.

The additive tank 5 for receiving the additive, in particular a foam agent 25, is connected via a line 26 to a conveying device 27 of the metering device 6 for additive. A shut-off valve 28 and check valves 29 are arranged in line 26.

The metering device 6 for additives essentially consists of a drive device 30 and the conveyor device 27. The drive device 30 consists of a cylinder 31, a piston 32 and piston rods 33 and 34. In the area of the piston rod 33 there is a transmitter 35 for determining the delivery frequency of the drive device 30 placed and connected to the control device 7 via a connecting line 36.

The cylinder 31 is provided with inlet openings 37, 38 and outlet openings 39, 40. The inlet openings 37, 38 are connected via a supply line 41 to the pressure line 18 of the extinguishing agent pump 4. A shut-off valve is in the supply line 41 42 arranged, as well as butterfly valves 43, 44, which can be switched over a switching device 45, for example a pneumatic actuating cylinder. Shut-off valves 46, 47 are also assigned to the outlet openings 39, 40, which in turn are connected to the switching device 45. The control of the individual butterfly valves 43, 44, 46 and 47 is made such that the diagonally opposite butterfly valves 43 and 47 or 44 and 46 are alternately opened or closed. This switchover can cause an alternating mutual displacement of the piston 32 from the system on one end wall to the opposite and vice versa. This reciprocating drive movement is made available via the piston rod 34 for actuating the conveying device 27.

A return line 48 between the outlet openings 39, 40 and the suction line 17 of the extinguishing agent pump 4 or the extinguishing agent tank 3 is provided with shut-off valves 49, 50, 51 and a control device 52 for the flow rate. The control device 52 for the flow rate is also connected to the control device 7 via a control line 53.

The conveying device 27 for additives is constructed similarly to the drive device 30 and is formed from a cylinder 54, a piston 55 and piston rods 56, 57. The conveying device 27 is connected in motion to the drive device 30 via the piston rods 34 and 56 in the stroke direction. The cylinder 54 of the conveying device 27 is also equipped with inlet openings 58, 59 and outlet openings 60, 61.

A pressure line 62 with check valves 63 in the area of the outlet openings 60, 61 connects the conveying device 27 to the admixing line 19 and subsequently via lines 64 and 65 to the group 10 of extinguishing agent outlets 11 and to the group 12 of extinguishing agent outlets 13. In the area shut-off valves 66, 67 of the extinguishing agent outlets 11 and 13 are arranged. A line 68 with a shut-off valve 69 enables a direct connection between the pressure line 18 of the extinguishing agent pump 4 and the groups 10 and 12 of the extinguishing agent outlets 11 and 13, bypassing the sensor 8 and the pressure line 62 for the foam agent 25, so that the extinguishing agent outlets 11 and 13 of groups 10 and 12 can only be charged with pure extinguishing agent without the addition of an additive. This has the advantage that, depending on the intended use, the respective outlets are rapidly and successively charged with different extinguishing agents can be.

Likewise, the extinguishing agent launcher 9 is connected via a line 70 to the pressure line 18 of the extinguishing agent pump 4 or via a line 71 to the metering device 6 for additives. Shut-off valves 72, 73 are arranged in lines 70 and 71 for switching over to different operating modes.

A flushing line 74 for cleaning purposes of the lines coming into contact with additive is provided between the pressure line 18 of the extinguishing agent pump 4 and the line 26. A line 75 with a shut-off valve 76 also enables liquid 14, for example from a hydrant 77 or an upstream extinguishing agent pump, to be fed into the suction line 17 between the shut-off valve 16 and the extinguishing agent pump 4.

Shut-off valves 78 are then arranged between the pressure line 18 and the flushing line 74 and between the return line 48 and the flushing line 74 for pressurization or for supplying extinguishing agent or flushing water into the flushing line 74. Via these shut-off valves 78, the flushing line 74 can be acted upon either by an external water source, for example a hydrant 77 or by the extinguishing agent pump 4.

All of the aforementioned shut-off valves 16, 28, 42, 49 to 51, 66, 67, 69, 72 and 73, as well as 76 and 78 can be designed as manually operated valves. In many cases, however, these shut-off valves 16, 28, 42, 49 to 51, 66, 67, 69, 72 and 73 - especially those which are often actuated during the extinguishing operation - will be provided as remote-controlled valves with electrical or fluidic drives. The control can then take place either centrally from the control and / or display device 7 via lines 79 or also via a central pressure fluid, for example compressed air. For example, it is shown that the changeover of the changeover device 45 formed by a cylinder piston drive is acted upon by a changeover valve 80 for reversing the control air in the opposite direction. This changeover valve 80 can be adjusted from one setting to the other via an actuator 81, for example likewise a pneumatic drive. The triggering of the adjustment from one end position to the other takes place via pneumatic limit switches 82, 83, each of which takes place from a stop plate 84 on the piston rod 33 in the two end positions of the piston 32 within the cylinder chamber 85. As a result, the movement of the piston 32 in the cylinder chamber 85 is always when it reaches its end position has moved by acting on the limit switches 82 and 83 in the opposite direction. As already mentioned above, this takes place in that compressed air is supplied from a compressed air source 86 via a changeover valve 80 via the changeover device 45, and thereby the cylinder chambers 85 and 87 are optionally filled with extinguishing agent, the in the opposite cylinder chamber 85 and 87 existing extinguishing agents are discharged via the diagonally arranged outlet opening 40 and 39 and discharged into the open via the shut-off valves 49 and 50 or via the return line 48 and the shut-off valves 51 to the suction line 17 of the extinguishing agent pump 4 or the extinguishing agent tank 3.

For admixing the additive e.g. of the foaming agent 25 via the conveying device 27 into the lines 64 and / or 65 and / or 71, the additive must have a higher pressure than the pressure of the extinguishing agent in these lines 64, 65, 71. Since the extinguishing water in the pressure line 18th by forwarding via the supply line 41 to the drive device 30 to drive the conveying device 27 for the additive, different pressures in the cylinder chambers 85, 87 and 88, 89 are required. The extrusion pressure exerted on the additive by the conveying device 27 must take into account the flow resistances in the check valves 63 and the pressure line 62 may be higher than the pressure of the conveying means in the admixing line 19.

This is done in such a way that an annular surface 90 of the piston 32 is at least 2% larger than an annular surface 91 of the piston 55. By designing the piston rods 56, 57 with the same diameter 92 and the piston rods 33, 34 with the same diameter 93 It is further ensured that the pressure conditions or the pressure difference in the additive and in the extinguishing agent are the same regardless of the direction of movement of the piston 32 in the cylinder 31 or 54.

Of course, the piston rods 33, 34 and 56, 57 in the individual cylinders 31 and 54 can also have different diameters 93 and 92, it only has to be ensured that the force generated by the drive device 30 is sufficient to drive the conveyor device 27 Raise the pressure in the additive to a value above the extinguishing agent.

The function of the device according to the invention for admixing additives with a higher pressure into a pressurized extinguishing agent, which is usually also referred to as a foam pressure proportioning system, now proceeds as follows: After opening the shut-off valve 16 or 76, liquid 14, for example water from an extinguishing agent tank 3 or from a hydrant 77 or from a feed line, is fed to the suction line 17 via an upstream extinguishing agent pump. The liquid 14 is sucked in above the negative pressure generated in the extinguishing agent pump 4 and discharged into the pressure line 18 at a pressure between usually 6 and 12 bar in high-pressure systems up to 40 or 50 bar.

If only pure extinguishing agent is required without any additives, the extinguishing agent or the liquid 14 is supplied to the lines 68, 70 via the supply line 41 and to the individual lines 64, 65 and 71 via the shut-off valves 69, 72 arranged thereon to the extinguishing agent launcher 9.

Individual or all of these extinguishing agent outlets 11 and 13 can be used to remove extinguishing agent via the corresponding shut-off valves 66, 67.

If, for example, an extinguishing agent mixture mixed with additive is now only required on the extinguishing agent launcher 9, the shut-off valve 72 is closed and the shut-off valve 42 is opened. This has the effect that the proportion of the extinguishing agent required for the extinguishing agent launcher 9 is no longer supplied to the extinguishing agent launcher 9 through the supply line 41, but via the transmitter 8 and the admixing line 19, into which the pressure line 62 from the conveying device 27 opens, via the Higher pressure additive is supplied and pressed into the admixing line 19. The extinguishing agent mixture consisting of extinguishing agent and additive is fed via line 71 to the extinguishing agent throwers 9, where appropriate mixed up and dispensed via a point of use, in particular a source of fire. This is because, by opening the shut-off valve 42, the extinguishing agent is supplied via the supply line 41 to the drive device 30, which sets the piston 55 of the conveying device 27 in reciprocating movements, as a result of which the latter is alternately generating negative pressure in the inlet openings 58, 59 to the cylinder chambers 88, 89 foam agent 25 from the additive tank 5, for example a canister, but it can also be a plastic or stainless steel tank, for example, after opening the shut-off valve 28 and sucked in via line 26 and with a pressure above the Extinguishing agent in the supply line 41 feeds pressure via the pressure line 62 after passing the check valves 63 into the admixing line 19.

The control and / or display device 7 is provided in order to ensure that a sufficient mixture of extinguishing agent, consisting of extinguishing agent and additive, matched to the respective flow rate, is led to the corresponding extinguishing agent outlets 11, 13 or extinguishing agent launcher 9. Via an input element 24, for example a selector switch, the admixing factor can be determined over a fraction, for example in percent, of additive to which a predeterminable amount of extinguishing agent is to be added. This measured value is stored in a setpoint memory 23. From this signal from the setpoint memory 23 and the flow rate to the admixing line 19, which is determined with the measuring value transmitter 8, a quantity of additional means required is predefined.

In order to enable the quantity of additives conveyed by the conveying device 27 to be monitored, the adjustment speed of the piston 32 of the drive device 30 and thus also the stroke frequency are monitored. This takes place, for example, via a measuring device 94, which can be formed, for example, by a light scale 95 with a scanning head 96 assigned to it. If, on the basis of the time period determined between the passage of two immediately adjacent markings 97, it is found that the amount of additive supplied to the admixing line 19 due to this stroke speed is not sufficient for the flow rate of extinguishing agent in the admixing line 19 determined by the transmitter 8, the comparator 22 generates a difference signal which, via the control line 53, causes an adjustment drive 98 of the control device 52 to increase the passage cross section in the control device 52. This increases the amount of extinguishing agent flowing through the cylinder chambers 85 and 87, and this causes a higher pumping frequency and thus a faster squeezing and refilling of the additive in the cylinder chambers 88 and 89.

If, on the other hand, the movement or the amount of additives conveyed into the pressure line 62 by the conveying device 27 is too large, the passage cross section for the extinguishing agent flowing out of the cylinder chambers 85 and 87 is reduced, as a result of which the flow rate through the cylinder chamber 85, 87 and thus the piston speed of the piston 32 is also reduced.

Thus, taking into account the changing flow rate of liquid 14 in the admixing line 19, an extremely exact and rapid admixing of the necessary additive quantities can be achieved without it being a drive source independent of the liquid 14 for sucking and pressing the additive into the liquid 14 needs.

Another advantage of this solution lies in the use of cylinder piston arrangements, with which an abundance of extinguishing and cleaning agents or other additives can be added to an extinguishing agent or water or a cleaning liquid, regardless of their viscosity.

Above all, this device is also insensitive to different viscosities of the additives, since the piston speed of the drive device 30 can be kept continuously at the desired stroke frequency, independently adjusting to the respective viscosity.

Furthermore, by actuating the subsequent system parts, in particular the drive device 30 from the pressure output of the extinguishing agent pump 4, the metering device 6 can also be operated during feed-in operation, that is to say when extinguishing agent is fed into the suction line 17, with a pressure of up to 16 bar.

Furthermore, the sensible arrangement of the individual lines and shut-off devices ensures that each individual extinguishing agent outlet 11 or 13 or each individual group 10 or 12 of such extinguishing agent outlets 11 or 13 and, for example, of extinguishing agent throwers 9 independently, but alternately only by switching over from individual Shut-off devices can be loaded with a mixture of extinguishing agent and additive or only with pure extinguishing agent.

A great advantage is also the low differential pressure between extinguishing agent and additive required in such systems, which only has to be so high that the pressure losses in the delivery system of the pressure medium, that is to say in the supply line, are compensated for.

The energy loss during the operation of such an admixing system is also very low, since only as much extinguishing agent or propellant water has to be taken from the pressure circuit of the extinguishing agent as is required for the production of a mixture of extinguishing agent and additive due to the respective dispensing quantity.

3 to 5 show a possible embodiment variant of the metering device 6 in its construction, but is shown schematically for better understanding. This metering device 6, for example referred to as a differential pressure piston pump, comprises a cylinder-piston arrangement 99, the cylinder 100 of which is divided into two piston chambers 102, 103 by a fixed distributor plate 101. The distributor plate 101 simultaneously forms a guide 104 for a piston rod 105, which connects two pistons 106, 107 arranged in the two piston chambers 102, 103 to one another in a stationary manner. A length 108 of the piston rod 105 is dimensioned such that in its respective end position one of the two pistons 107 or 106 rests on an end plate 109 which delimits the piston chamber 102 or 103 and has a front side 110 facing it, while the other piston 106 or 107 with its Inner side 111 abuts the distributor plate 101.

In the opposite end position, the inside 111 of the piston 107 then bears against the distributor plate 101 and the front side 110 of the piston 106 against the end plate 109. One of the two pistons 106, 107 or both are connected to a further piston rod 112, which extends through the piston chamber 102 and / or 103 in the direction of the end plates 109 and has a length that is greater than a stroke length 113 of the pistons 106, 107 in the piston chambers 102, 103.

The piston 106 creates two separate cylinder chambers 114, 115 in the piston chamber 102 and two separate cylinder chambers 116, 117 in the piston chamber 103.

Because the piston rod 105 has a considerably larger diameter 118 than a diameter 119 of the piston rod 112, the displacement area of the inner sides 111 of the two pistons 106, 107 is considerably smaller than on the front side 110 Diameter 118 to 119 or, based on the volume ratio between the cylinder chambers 114, 117 and the cylinder chambers 115, 116, a proportionality between the delivery quantity and the delivery pressure in the cylinder chambers 114, 117 with respect to the cylinder chambers 115, 116 is established.

This creates the possibility, for example with a predetermined delivery pressure for acting on the front sides 110 of the pistons 106, 107, to press out the liquids contained in the cylinder chambers 114 and 117 with higher pressure.

Thus, the same effect can be achieved with the cylinder piston arrangement 99 as with the cylinders 31 and 54 of the cylinder piston arrangements separated from one another, as shown in Fig. 2, the piston rods 34 and 56 are only motionally connected.

The metering device 6 can therefore be used instead of the metering device 6, as shown in FIG. 2, which is why only the configuration of the metering device 6 is described in FIGS. 3 to 5 and the remaining control arrangement or the sequence of the mixing corresponds to that as described in Fig. 2.

Thus, the supply line 41 is connected to an inlet connection 120, which is designed as a piece or is connected via a piece to the inlet openings 37 and 38. Shut-off flaps 43 and 44 are arranged between the inlet connection 120 and the inlet openings 37, 38 and are connected in motion via a lever linkage to a switching device 45 formed by a cylinder piston arrangement 121. The cylinder piston arrangement 121 is pivotally attached via a support bracket 122 to the cylinder 100 or on another housing part which also supports the cylinder 100 and is connected to its piston rod 123 in a rotationally fixed manner with a pivot axis 125 via a pivot lever 124. On this pivot axis 125 there is another pivot lever 126 which is connected to it in a rotationally fixed manner and which is connected via a push rod 127 to a pivot lever 128 in the region of the respectively opposite inlet opening and outlet opening 38, 40 assigned to butterfly valves 44 and 47. Due to the arrangement selected in particular from FIG. 3 and the right part of FIG. 5, not only the butterfly valves 46 and 47 leading to the return line 48, which are arranged upstream of the outlet openings 39, 40 for the pressure medium, but also the butterfly valves 43 and 44 , which are arranged upstream of the inlet openings 37 and 38 for the pressure medium.

By reversing the switching device 45, an alternate application of pressure medium from the extinguishing agent pump 4 to the cylinder chambers 115, 116 is achieved, which leads to a reciprocating movement of the pistons 106, 107. By means of these pistons 106, 107, in addition to each other, when they move in the direction of one of the end plates 109 in the cylinder chamber 117 facing away from the latter via a line 26, check valves 29 and inlet openings 58 and 59, additional means are supplied to the cylinder chambers 117 and 114, respectively.

Thus, for example, while in the position shown in FIGS. 3 to 5 the additive, for example foam agent 25, has just been sucked into the cylinder chamber 117, the foam agent 25 sucked into the cylinder chamber 114 in the previous stroke is over an outlet opening 60 and a check valve 63 are supplied to the pressure line 62 for the foaming agent 25.

When the stroke shown is completed, the foam agent 25 then sucked into the cylinder chamber 117 is fed to the pressure line 62 via an outlet 61 and a further check valve 63.

Due to the reversal of the switching device 45, a continuous flow of foaming agents 25 in the pressure line 62 for admixing into the extinguishing agent in the admixing line 19 is therefore generated by the reciprocating movement of the pistons 106, 107.

As has already been explained in more detail with reference to the illustration in FIG. 2, the amount of the additive or foam agent 25 to be mixed is now regulated by the number of strokes of the pistons 106 and 107 in the time unit. The control components already described in detail in FIG. 2 and the control and / or display device 7 can be used for this purpose.

Likewise, in the present exemplary embodiment, the number of strokes of the pistons 106, 107 is regulated by regulating the outlet cross section to the return line 48 by means of the regulating device 52. For this purpose, an adjusting drive 98, for example a linear adjusting drive coupled to a stepping motor, is rotatably fixed via a pivot lever 129 with a pivot axis 130 of a metering flap 131 in the control device 52. If the number of strokes in the cylinder piston arrangement is to be increased, the metering flap 131 is pivoted more so that it opens up a larger passage cross section in the control device 52 and a larger amount of liquid 14 can thus be pumped through the cylinder chambers 115, 116.

In accordance with the number of strokes in the latter-mentioned pistons 106, 107 in the cylinder chambers 115, 116, the amount of the additive or foam agent 25 applied via the cylinder chambers 114, 117 is also increased proportionally.

To monitor the stroke movement of the pistons 106, 107, the piston rod 112 can now be used in an equivalent manner to the piston rod 33 according to FIG. 2 and accordingly a measuring device 94 and limit switches 82, 83 can be assigned to it.

Of course, it is also possible to use any other monitoring device with which the position of the pistons 106, 107 in the cylinder 100 or the speed of movement thereof can be monitored. For example, it is possible to monitor these by means of the interrogation elements attached to the outside of the cylinder 100, which respond to sensors 106 and / or 107, or to provide the piston rod 105, in which case the corresponding measuring device 94 would have to be arranged in the distributor plate 101 .

For the rest, all devices known for such movement monitoring from the prior art can be used for the measuring device 94.

6 shows a variant of the dosing device 6. The arrangement of the admixing device 2 is shown in a very simplified manner and essentially corresponds to that shown in FIG. 2. The same reference numerals are therefore used for the same parts.

The extinguishing agent pump 4 is supplied with liquid 14 from the extinguishing agent tank 3 via the suction line 17. After flowing through the pressure line 18 and the measuring sensor 8, the liquid 14 in the admixing line 19 is mixed with foam agent 25 from the additive tank 5 and made available, for example, to a group 10 of extinguishing agent outlets 11.

The admixing factor between a predetermined amount of a liquid 14 and the amount of foam agent 25 to be added can in turn be preset via the input member 24 and regulated accordingly via the control and / or display device 7. In this exemplary embodiment, the metering device 6 consists of a rotating drive device 132, for example a vane pump 133 or an equivalent unit such as a rotary vane pump, which can either be single-stroke or also multi-stroke, and a likewise rotating conveying device 134, which in the same way works with a vane pump 133 can be designed like the drive device 132. The drive device 132 and the conveyor device 134 are connected to one another in a rotationally fixed manner. A measuring device 94, which is formed by a sensor 135, detects the speed of the drive device 132 of a rotor 136 of the vane pump 133 and transmits this via the connecting line 137 to the control and / or display device 7. As already described in FIG the determined result from the control and / or display device 7 via the control line 53 to the adjustment drive 98 of the control device 52. With this adjustment drive 98, as also already explained in detail with reference to FIG. 2, the flow rate of the liquid 14 through the drive device 132 or vane pump 133 is regulated such that the required amount of additive due to the direct drive coupling of the drive device 132 of the conveying device 134 or foam agent 25 is supplied via the pressure line 62 to the admixing line 19.

The pressure difference required to add the foam agent 25 in the admixing line 19 to the liquid 14 is determined by different diameters of the rotor 136 of the drive device 132 and of the rotor 136 of the conveying device 134, i.e. achieved by the different total volume of the volume chambers of the drive device 132 and the conveyor device 134. The total volume of the volume chambers is to be understood, for example, that with the same number of vanes of a vane pump for the drive device 132 and the conveyor device 134, the sum of the volumes of the volume chambers between the individual vanes in the drive device 132 is greater than in the conveyor device 134.

The greater the difference between the sum of the volume chambers or, in the exemplary embodiments according to the previous exemplary embodiments, of the cylinder chambers 85, 87 or 88, 89 forming the volume chambers, the greater the difference between the pressure in the liquid 14 in the pressure line 18 or the pressure of the additive or foam agent 25 in the pressure line 62, the total volume or the volume of the volume chambers of the conveying device 134 usually being smaller than that of the drive device 132 and therefore the pressure in the pressure line 62 being higher by the transmission factor take into account that the pressure in the pressure line 62 should be higher, at least by the drive losses of the conveying device 134, as well as by the friction losses between the additive tank 5 and the confluence of the pressure line 62 into the admixing line 19, in order to ensure that the additive or foam agent 25 is mixed in properly to reach.

7 shows another embodiment of the control and / or display device 138 for manual regulation in order to maintain the mixing ratio of a mixing amount of foam agent 25 for a predefined amount of liquid 14. The structure of the admixing arrangement 2 is shown in simplified form in a block diagram. The metering device 6 corresponds essentially to that shown in FIG. 2, and the same reference numerals are therefore used for the same parts.

By means of an extinguishing agent pump 4, liquid 14 from an extinguishing agent tank 3 is pressurized and provided on the one hand to the drive device 30 via the pressure line 18 and on the other hand mixed with foam agent 25 in the admixing line 19 and subsequently made available to a group 10 of extinguishing agent outlets 11. The foam agent 25 is sucked out of the additive tank 5 by means of the conveying device 27 and conveyed via the pressure line 62 into the admixing line 19 and added to the liquid 14 there.

A manual control and / or display device 138 is provided to regulate the mixing ratio between a predetermined amount of a liquid 14 and the amount of foam agent 25 to be added. The control and / or display device 138 consists of a display unit 139, which is arranged, for example, in the driver's cabin of an emergency vehicle or on a pump control station, and spring-loaded pistons 140, 141, which in turn are pressurized via lines 142, 143. A measuring device 144 between the pressure line 18 and the admixing line 19 determines the flow rate of the liquid 14 which is to be mixed with a foaming agent 25. Likewise, a measuring device 145 is arranged between the pressure line 62 and the admixing line 19 for determining the flow rate of the foaming agent 25 which is to be added to the liquid 14.

Depending on the flow rate of the liquid 14 or the foam agent 25, a measuring piston 146 or 147 is raised, whereupon the amount of fluid thereby displaced in a line 143, 142 adjusts the pistons 141 and 140 of the control and / or display device 138 accordingly. As a result, the piston 141 together with the firmly connected scale 148 moves against the spring force of the spring 149. Likewise, the piston 140 is displaced with a pointer 150 firmly connected to it against the spring force of the spring 151.

Due to the determined flow rate in the respective measuring devices 144, 145, the pistons 140, 141 of the control and / or display device 138 are shifted to different degrees. This creates a relative movement between the pointer 150 and the scale 148. On the display unit 139, the current mixing ratio between a liquid 14 and the amount added to it can now be shown on the display unit 139 due to the position of the pointer 150 in relation to the scale 148 Read off foam agent 25. It goes without saying that the individual pistons 140, 141 of the measuring devices 144, 145 in the lines 142 and 143 to adjust the amount of fluid displaced in proportion to the size comparison made. It should be taken into account that, for example, the flow rate in the area of the foam agent 25 is approximately 30 liters of additive 25 to 1000 liters of liquid 14, and it is therefore the ratio of the transmission ratio between the measuring device 144 and the piston 141 or the scale 148 arranged on it to adjust the piston 140 with the pointer 150 arranged thereon, which is acted upon by the measuring device 145, approximately in a ratio of 100: 3 or 100: 1.

A manually operated control device 152 for controlling the admixing quantity is arranged in the return line 48 between the drive device 30 and the suction line 17. The flow rate of the liquid 14 required for the operation of the drive device 30 is controlled with the aid of the control device 152. In conjunction with the display unit 139, a desired admixing ratio can thus be set by actuating the control device 152, in which the admixture factor on the display unit 139, which is too low for the desired admixture, increases the flow rate of the liquid 14 for the drive device 30 and increases the flow rate if the admixture factor is too high the quantity of the liquid 14 can be reduced in the admixing factor displayed on the display unit 139.

For the rest, the admixing process and the operation of the metering device 6 are carried out analogously to the device already described in FIG. 2.

Because the dosing devices 6 shown and described are independent of the viscosity of the foam agent 25, a wide variety of additives can now be mixed with a liquid 14 using this dosing device 6. This includes, for example, a multigrade foam agent (F-5, F15, F30), protein foam foam, water film-forming foam agent, fluorine protein foam agent, LIGHT WATER ATC, irritant liquids, paints and the like.

Due to the compact design, in particular in the manufacture of the drive and conveying device 27 or 30 according to the exemplary embodiment shown in FIGS. 3 to 5, it is also easily possible if the measuring device and, if appropriate, the control and / or display device 7,138 are assigned accordingly to design this as a compact, self-transportable admixing device which can be operated independently of a vehicle or an extinguishing agent pump 4, for example via hose feed. The control and / or display device 7.138 can have its own Power supply can be supplied with energy, or a corresponding battery can be installed in such a compact device to operate the same. The compressed air can also be supplied via a hose line. Equally, however, it would also be possible, for example, to carry out the reversal of the individual valves using branched amounts of the extinguishing agent via hydraulic valves and hydraulically actuated cylinders.

A possible arrangement of such an embodiment variant is shown in FIG. 7 with dash-dotted lines. Instead of a compressed air source 86, a liquid 14 is fed via a line 153 to the changeover valve 80, a hydraulic valve for this embodiment variant. As already described in FIG. 2, the changeover valve 80 is actuated by means of an actuator 81 by alternately actuating the limit switches 82, 83, and subsequently the changeover device 45, in this case a hydraulic cylinder, is alternately acted upon by liquid 14. The return of the liquid 14 takes place from the changeover valve 80 to the outside or via a line 154, e.g. to the extinguishing agent tank 3 or to the suction line of the extinguishing agent pump 4.

This embodiment variant is preferably used in a transportable structural unit of the drive and conveyor device 27, 30.

Likewise, instead of an electrical or electronic control and / or display device 7, a manual or mechanical control and / or display device 138 could also be provided in such a compact device.

The removal of the additive or foam agent 25 can be done via a hose line e.g. also from portable canisters as additive tank 5.

The advantage of a transportable structural unit composed of these aforementioned parts and devices is that it can be used independently of stationary systems or vehicles, even at distant water extraction points, for the exact admixture of additives with different conveying capacities of extinguishing agents.

Finally, for the sake of order, it should only be mentioned that for a better understanding of the function of the admixing device 2 individual parts of the same are greatly distorted to scale and are disproportionately or purely schematically represented.

Of course, all individual parts known to the person skilled in the art and known from the prior art for the motors, cylinders, valves and the like can be used for the individual components of the admixing device 2 according to the invention.

The individual exemplary embodiments according to FIGS. 1 to 7 can also each form independent solutions according to the invention, and individual characteristics of these individual exemplary embodiments combined with other individual characteristics from the other exemplary embodiments can also form a combination according to the invention.

List of reference symbols

1

Fire engine

2nd

Proportioning device

3rd

Extinguishing agent tank

4th

Extinguishing agent pump

5

Admixture tank

6

Dosing device

7

Tax and / or display

8th

device transmitter

9

Extinguishing agent launcher

10th

group

11

Extinguishing agent outlet

12th

group

13

Extinguishing agent outlet

14

liquid

15

Tank outlet line

16

Shut-off valve

17th

Suction pipe

18th

Pressure line

19th

Admixture line

20th

management

21

Comparator

22

Comparator

23

Setpoint memory

24th

Input organ

25th

Foaming agent

26

management

27

Conveyor

28

Shut-off valve

29

check valve

30th

Drive device

31

cylinder

32

piston

33

Piston rod

34

Piston rod

35

Sensor

36

Connecting line

37

Inlet opening

38

Inlet opening

39

Outlet opening

40

Outlet opening

41

supply line

42

Shut-off valve

43

Butterfly valve

44

Butterfly valve

45

Switching device

46

Butterfly valve

47

Butterfly valve

48

Return line

49

Shut-off valve

50

Shut-off valve

51

Shut-off valve

52

Control device

53

Control line

54

cylinder

55

piston

56

Piston rod

57

Piston rod

58

Inlet opening

59

Inlet opening

60

Outlet opening

61

Outlet opening

62

Pressure line

63

check valve

64

management

65

management

66

Shut-off valve

67

Shut-off valve

68

management

69

Shut-off valve

70

management

71

management

72

Shut-off valve

73

Shut-off valve

74

Flush line

75

management

76

Shut-off valve

77

hydrant

78

Shut-off valve

79

management

80

Diverter valve

81

Actuator

82

Limit switch

83

Limit switch

84

Stop plate

85

Cylinder chamber

86

Compressed air source

87

Cylinder chamber

88

Cylinder chamber

89

Cylinder chamber

90

Circular surface

91

Circular surface

92

diameter

93

diameter

94

Measuring device

95

Light scale

96

Readhead

97

mark

98

Adjustment drive

99

Cylinder piston arrangement

100

cylinder

101

Distribution plate

102

Piston chamber

103

Piston chamber

104

guide

105

Piston rod

106

piston

107

piston

108

length

109

Faceplate

110

front

111

inside

112

Piston rod

113

Stroke length

114

Cylinder chamber

115

Cylinder chamber

116

Cylinder chamber

117

Cylinder chamber

118

diameter

119

diameter

120

Inlet connector

121

Cylinder piston arrangement

122

Support tab

123

Piston rod

124

Swivel lever

125

Swivel axis

126

Swivel lever

127

Push rod

128

Swivel lever

129

Swivel lever

130

Swivel axis

131

Metering flap

132

Drive device

133

Vane pump

134

Conveyor

135

Sensor

136

rotor

137

Connecting line

138

Control and / or display device

139

Display unit

140

piston

141

piston

142

management

143

management

144

Measuring device

145

Measuring device

146

Volumetric flask

147

Volumetric flask

148

scale

149

feather

150

pointer

151

feather

152

Control device

153

management

154

management

Claims (20)

Mixing device for mixing additives to a liquid, in particular an extinguishing agent e.g. in fire-fighting vehicles with a pressure line for the liquid with a sensor for the flow rate in this pressure line arranged therein, with a drive device for a conveying device for the additive from an additive tank into an admixing line connected to the pressure line via a supply line, with a control device for the flow rate of the liquid through the drive device as a function of the amount of liquid flowing through the pressure line, the drive device being motionally connected to the conveying device, characterized in that the supply line (41) for the drive device (30, 132) branches off in front of the measuring device in the direction of flow of the liquid (14) and the control device (52, 152) is connected downstream of the drive device (30, 132) in the flow direction of the liquid (14) and that a control and / or display device (7, 138) is arranged, ie e has a transducer (8) of the measuring device and an input element (24) for a quantity of liquid that can be added or a measuring device (145) for determining the quantity of additives supplied. Mixing device according to claim 1, characterized in that a measuring device (94) for a movement speed, in particular the lifting or rotating speed of the drive device (30, 132) is connected to the control and / or display device (7). Mixing device according to claim 1 or 2, characterized in that an output of the control and / or display device (7) is connected to an adjusting drive (98) of the control device (52). Mixing device according to one or more of claims 1 to 3, characterized in that the volume of the cylinder chambers (85, 87) acting as volume chambers of the drive device (30, 132) is greater than the volume in the cylinder chambers (88, 89) acting as further volume chambers Conveyor device (27, 134). Mixing device according to one or more of claims 1 or 4, characterized in that the two pistons (106, 107) of the drive and conveying device (30, 27) are arranged on a common piston rod (105) which is guided in a distributor plate (101) arranged between these receiving cylinders (100). Mixing device according to one or more of claims 1 to 5, characterized in that the cylinder chambers (114, 117) between the two pistons (106, 107) and the distributor plate (101) convey the device (27) and between the pistons (106, 107) and the End plates (109) of the cylinder chambers (115, 116) arranged for these cylinders (100) form the drive device (30). Mixing device according to one or more of claims 1 to 6, characterized in that a line (26) between the conveying device (27) and the additive tank (5) and a pressure line (62) between the conveying device (27) and the admixing line (19) open into the distributor plate (101). Mixing device according to one or more of claims 1 to 7, characterized in that non-return valves (29, 63) are arranged between the line (26) and the pressure line (62). Mixing device according to one or more of claims 1 to 8, characterized in that a volume of suction or pressure chambers of a rotating drive device (132) and conveyor device (134) acting as volume chambers is of different sizes and that the volume of the volume chambers of the drive device (132 ) is greater than that of the conveyor (134). Mixing device according to one or more of claims 1 to 9, characterized in that the drive device (132) and / or the conveying device (134) by a rotating pump, e.g. Vane pump (133) or radial piston pump or axial piston pump or the like. Is formed. Mixing device according to one or more of claims 1 to 10, characterized in that several drive (30, 132) and / or conveying devices (27, 134) are connected in parallel. Mixing device according to one or more of claims 1 to 11, characterized in that the drive device (132) and / or the conveying device (134) is formed in several stages. Mixing device according to one or more of claims 1 to 12, characterized in that the control device (152) is designed as a manual slide and is arranged in the region of a display unit (139). Mixing device according to one or more of claims 1 to 13, characterized in that the display unit (139) is formed by two adjustable pistons (140, 141), each of which has a pressure piston in a line (142, 143) with a measuring piston (146 , 147) of the measuring devices (144, 145) are motionally connected and that a pointer (150) is attached to a piston (140) and a scale (148) is attached to another piston (141) and the pointer (150) and the scale ( 148) are displaceable parallel to one another and the pistons (140, 141) are under a bias of springs (149, 151) directed in the direction of the measuring pistons (146, 147). Mixing device according to one or more of claims 1 to 14, characterized in that in a drive device (30) formed by a cylinder piston arrangement, two limit switches (82, 83) are assigned to a piston rod (33), each of which is in the end positions of the piston (32) are preferably acted upon alternately via a stop plate (84) and each of the limit switches (82, 83) is connected to an actuator (81) of a changeover valve (80) which supplies pressure medium from a compressed air source (86) to drive the changeover device (45) acted upon, the position of the changeover valve (80) being acted upon when a limit switch (82, 83) is acted upon in the sense of a reversal of movement of the piston (32). Mixing device according to one or more of claims 1 to 15, characterized in that a piston rod (33) of the drive device (30) is assigned a measuring device (94) consisting of a scanning head (96) and a light scale (95) and the control and / or display device (7) for evaluating the relative speed between the light scale (95) and the scanning head (96). Mixing device according to one or more of claims 1 to 16, characterized in that the drive and conveying device (30, 27) with the measuring device and the control device (52) and optionally the control and / or display device (7, 138) form a transportable structural unit. Method for admixing additives to a liquid, in particular an extinguishing agent, in which a flow rate of a pressurized liquid is determined, part of this liquid is fed to a drive device which is coupled to a conveying device for an additive and with which the additive is added from an additive tank a mixing line is fed and the delivery rate of the additive is regulated by regulating the flow rate of the liquid through the drive device as a function of the flow rate of extinguishing agent, characterized in that the liquid for the drive device before determining the delivery rate of the liquid to those extinguishing agent outlets that are to be supplied with a mixture of extinguishing agent or additive, is branched off and that a receiving volume of the drive device per revolution or per stroke is greater than a delivery volume of the conveyor device tion per revolution or stroke and that the difference between the receiving volume and the delivery volume is greater than the flow transmission losses between the drive and delivery device, as well as the flow losses between the additive tank and the admixing line and the flow rate of the liquid through the drive device after the drive device depending on the respectively to be added Amount of additives is regulated. A method according to claim 18, characterized in that the rotational speed or the lifting speed of the drive device is determined and the dependence on the flow rate of the extinguishing agent or the liquid to the extinguishing agent outlets is regulated. The method of claim 18 or 19, characterized in that the liquid emerging from the drive device is supplied to the suction line of the extinguishing agent pump or to an extinguishing agent tank arranged upstream of the extinguishing agent pump.

Images