EP0343320B1 - Apparatus for fire-extinguishing installations with an electronically controlled automatic mixing device - Google Patents

Abstract

The invention relates to an apparatus with an electronically controlled automatic mixing device, in particular for fire-extinguishing installations, which can be used both for stationary and for mobile installations and equipment. The adjustment of the control valve is effected via a digital control on a microprocessor basis, the electronic control being subdivided into a basic electronic system and an operation terminal. <IMAGE>

Description

The invention relates to a device with an automatic, electronically controlled admixer, in particular for fire extinguishing systems, with which a foam agent is sucked in from a storage container and admixed under pressure in a controlled amount with the extinguishing water, the foam agent being metered automatically by a control element provided in the foam agent line , which is operated in conjunction with flowmeters from basic electronics with a digitally controlled microprocessor, the extinguishing water / foam mixture being supplied to several consumers via branch lines, the extinguishing water / foam mixture and the foaming agent being measured quantitatively by the flowmeters and both measured values being measured with a setpoint-fed basic electronics are fed and the dosage of the foam agent taking into account the current flow rate of extinguishing water-foam agent mixture and the set default value Control of the control valve resulting from a target / actual comparison is carried out automatically.

Such a device (DE 37 26 672 A1) is used for mobile systems, such as fire-fighting vehicles, with high mixing accuracy and large flow measuring ranges. These advantages are bought when the water-foam mixture is divided into two.
Electronically controlled admixers have already been used in mobile devices. In the case of the stationary systems, the pure admixing function was carried out by a normal pre-mixer, which works on the principle of the water jet pump. This proportioning device is built into the bypass of a water pump, between the pump outlet (pressure side) and pump inlet (suction side). In addition to these pump premixers, mixing devices are also known which operate using a foam agent pump based on the differential pressure principle, or with speed-controlled volumetric metering pumps, or in which the signal of the water flow is converted mechanically to control the foam agent flow.

Also in a fire truck, it is known from DE-OS 30 38 334) to provide a volumetric metering pump that is speed-controlled by a control unit.

Furthermore, electronically controlled admixing devices are known which mix a second stream in a preselectable ratio with a main stream. See also EP-PA 0230860 and DE-OS 30 38 334.

These systems have the disadvantage that they have to work with partial flows either on the admixing side and / or on the consumer side in order to realize a large flow range, since the measuring sensors do not measure sufficiently precisely and the control elements are not suitable for covering larger areas.

Another disadvantage is that these analog systems sometimes react sluggishly, tend to overshoot, which then has to be dampened by additional electronic effort, which again affects the accuracy and response of the control. Furthermore, the regulation is negatively influenced by changes in temperature and viscosity.

The invention is based on the provision of creating an electronic admixing system which covers a wide admixing range, which responds quickly and whose electronics can be used in a variety of ways. In addition, the system should be easy to use and can be adapted to other tasks with little effort (software change). Another object of the invention is to simplify the line routing so that the admixing performance does not have to be split.

This object is achieved in that the basic electronics are provided with two programming fields in which the area of application and the desired default value can be selected, that a self-optimizing control algorithm is provided for the control valve, which prevents the control valve from overshooting, and that the microprocessor also is provided with a watchdog which, in the event of a fault, causes all important data to be stored in RAM.

The admixing system according to the invention is intended in particular for mounting on fire engines and for use in stationary fire extinguishing systems. It automatically mixes the set amount of foaming agent or another suitable additive into the water flow and keeps it constant as a percentage over the entire specified flow range. The water flow and the foam agent flow are measured electrically and a target / actual value comparison is carried out taking into account the specified admixture and differences are compared by an electrical control unit until the actual value corresponds to the target value.

Fig.1

ein Fließschema des Zumischsystems für eine mobile Feuerlöschanlage,

Fig. 2

ein Blockschaltschema der Elektronik.

Further details are marked in the subclaims. An embodiment is shown schematically in the drawing and is described in more detail below. It shows:

Fig. 1

a flow diagram of the admixing system for a mobile fire extinguishing system,

Fig. 2

a block diagram of the electronics.

The foam agent is sucked by a pump 1 out of the tank 2 by means of a line 3 and fed to the water line 7 coming from a water tank 6 via a control valve 4 equipped with a control element monitoring and a flow meter 5. Between the foam agent pump 1 and the control valve 4, a foam agent return line 8 to the foam agent tank 2 is provided via a shut-off element 9 and an overflow valve 10. Furthermore a bypass 12 is placed parallel to the measuring and controlled system via a shut-off element 11, in which a diaphragm 13 is located. In the line 17 carrying the mixture there is a flow meter 14 with which the instantaneous consumption of the foam agent / water mixture is determined and supplied to the basic electronics 15. After the flow meter 14, the pressure line 17 branches behind the pump 25 in lines 18 and 19 to supply the various consumers 20 and 21 to 23. Thus 20 can be a foam jet pipe and the consumers 21 to 23 of any type. A rinsing line 24 is connected to the pressurized water side of the pump 25 and is guided into the suction line 3 of the foam agent pump 1 via a pressure reducer 26 and a shut-off device 27. Shut-off devices 28, 29 and 30 are also provided.

The electronic control of the admixing device is divided into basic electronics 15 and an operating terminal 16 and is structured as follows.
The components of the basic electronics 15 are accommodated in a splash-proof housing 15a and are connected by appropriate lines 31 to 39 to the measuring devices 5, 14, the control valve 4, the corresponding shut-off elements 9, 11, 27, 29, 30 and the control panel 16. The control panel 16, which is preferably placed in the driver's cab in the case of mobile fire-fighting vehicles, contains the pushbuttons which are important for foam operation and are described in more detail below, and a control display.

If necessary, a second control panel, e.g. be placed near the water pump or elsewhere on the vehicle.

The system according to the invention has the following functions.

business

When the system is switched on, a default value (preselected proportioning rate in percent) is output on the display 16a in the operator terminal. This displayed value can be changed positively and negatively in 0.1% steps within the specified limit values using two buttons.

foam

In the foam operating mode, the FOAM pushbutton must be pressed, which lights up yellow as feedback. With water throughput, an admixture in the amount of the default value is automatically set. The following functions are performed when the FOAM push button is pressed:
The valve 30 of the foam agent tank 2 opens, the foam agent pump 1 is activated, the control valve 4, which is in a central position, adjusts the foam agent flow according to the selected admixture and the current water consumption. The flow of the foam agent is indicated by the indicator lamp flashing. If the water flow is stopped when a foam is used, for example when working in shots or in a waiting position, the control valve 4 closes and the foam agent is supplied to the foam agent tank 2 via the shut-off element 9 and overflow valve 10. Likewise, if the amount of foam agent required is low, the foam agent that is not required is fed back into the tank 2.

When the foam insert is completely finished, press the FOAM pushbutton again. The valve 30 of the foam agent tank 2 closes, the foam agent pump 1 stops, the control valve 4 moves to the rest position.

Flushing

After the foam has been used, the RINSE button must be pressed to rinse the line system. The shut-off element 27 of the rinsing line 24 opens, the shut-off element 30 of the foam tank 2 remains closed, the shut-off element 9 of the tank return closes, the shut-off element 11 of the bypass 12 opens, the foam agent pump 1 runs, the control valve 4 opens fully. The water then flows through the pressure reducer 26 into the line 3, so that the latter and the bypass line 12 are flushed.

When the rinsing process is finished, press the RINSE push button again. The shut-off devices of the flushing and the bypass 12 close, the pump 1 stops, the control valve 4 moves to the rest position.

Emergency operation

If a fault occurs in the control unit during foam operation, the EMERGENCY push button must be pressed. This ensures that foam can be generated even in the event of a fault. When the NOT push button is pressed, the controlled system is closed by the shut-off device 29 and the bypass 12 is opened by a further shut-off device 11. The foam agent pump 1 remains activated, the tank shut-off valve 30 remains open.

A constant flow of foam agent is then entered via the bypass 12 through an orifice 13, the orifice being matched to the foam agent used and to the consumption of the launcher or the largest consumer.

Basic electronics

The interference-free interfaces in the basic electronics are connected to the interfaces of the operator terminal using standard 5-pin cables. A microprocessor system with the components CPU, PIO, ROM and RAM manages and operates inputs and outputs of the control valve 4, as well as those of the flow meters for water 14 and additives 5 and also provides a documentation and expansion interface. The analog signals from the flow meters for water and additives are fed to the microprocessor system via A / D converters. Influencing the resolution accuracy by pump shocks (ripple) are hidden by digital filters.

In order to make the basic electronics universally applicable for the manufacturer, the following four measuring ranges can be set.

First measuring range

Water:

400 l / min to 4,000 l / min

Foam agent:

0.4 l / min to 20 l / min

Second measuring range

Water:

400 l / min to 8,000 l / min

Foam agent:

2 l / min to 80 l / min

Third measuring range

Water:

400 l / min to 8,000 l / min

Foam agent:

4 l / min to 240 l / min

Fourth measuring range

Water:

400 l / min to 8,000 l / min

Foam agent:

12 l / min to 640 l / min

These areas can be varied as required by changing the software. In order to make operation easier, faster and safer, a selectable, measurement range-dependent default value is provided. When the electronics are switched on, the preselected TARGET value in percent appears as the default value on the display of the terminal. Using suitable programming fields, the measuring range and the default value of the target value are selected by the commissioning group before use.

Default values in% for the measuring range

Example:

Wanted to be stuck Measuring range 2 - default value 0.7% Field 1: 1 + 2 and 5 + 6 Field 2: 2 + 3 and 4 + 5.

The default values can also be changed again by changing the software.

An automatic fault blanking is implemented via a monitoring device (watchdog), which in the event of a fault causes all important data to be stored in RAM. A self-optimizing control algorithm for the control element 4 ensures an admixture that realizes a control difference with an accuracy of ± 1 digit without overshooting with the highest possible adjustment speed. This type of control avoids all disadvantages of the analog control, such as temperatures, viscosity dependency and damping-related control deviations. In order to optimize the reaction times even in the case of extreme admixing rates in both the lower and the upper flow range, the control element is provided with an adjustable starting position (usually a middle position). When the electronics are switched on, this rest position is checked and corrected if necessary. In order to detect connection and wiring errors when the digital admixing control is started up, the control unit is equipped with rotation direction sensors which output an error code via the display. To log the current values, such as water flow, Additive flow, set admixture values, date and time, a documentation interface is provided for connection to external analog and digital recording devices. The digital admixing control is also suitable for use in stationary systems (eg additive admixture in sprinkler systems). Switching on and activating can be triggered by a fire alarm control panel via quiescent current monitoring.

An integrated expansion interface allows external operation of all functions that are available on the terminal (remote control by radio).

In addition to use in fire extinguishing systems, the device according to the invention can be used wherever two fluids have to be mixed in a certain ratio. So e.g. in the production of lemonades from a concentrate, in water softening, etc.

Claims (12)

1. Device with an automatic, electronicaliy controlled mixer, particularly for fire-extinguishing installations, with which a foaming agent is sucked out of a supply container (2) and mixed under pressure with the extinguishing water in a controlled amount, where the metering of the foaming agent is effected automatically by means of regulating device (4) located in the foaming agent line (3), which is operated by an electronic circuit (15) with a digitally controlled microprocessor in combination with flow-measuring equipment (5,14), where the extinguishing water-foaming agent mixture is supplied along branch lines (20, 21, 22, 23) to several users, where the extinguishing water-foaming agent mixture and the foaming agent are quantitatively recorded by the flow-measuring equipment (5, 14) and both measurements supplied to the electronic circuit (15) fed with a nominal value and where the metering of the foaming agent automatically follows, taking into account the actual flow rate of the extinguishing water-foaming agent mixture and the metering value set by comparison of nominal and actual values, by controlling the control valve (4), characterised in that the electronic circuit (15) is provided with two programmable fields in which the useable range and the desired default value are selectable, that a self-optimising rule algorithm is provided for the control valve (4) which prevent overshooting of the control valve and that the microprocessor is provided with a watchdog, which ensures that, in the event of interference, all important data in RAM is taken off.
2. Device in accordance with Claim 1, characterised in that the control valve (4) is provided with sensors, which indicate the direction of rotation and wiring failures by means of a code on a display (16a) served by the microprocessor on the electronic circuit (15).
3. Device in accordance with Claims 1 and 2, characterised in that, for reporting the actual values measured, the microprocessor is provided with a documentation interface to which external analog and digital recording equipment can be connected.
4. Device in accordance with Claims 1 to 3, characterised in that the control valve (4) is provided, for more rapid reaction, with a device for adjustable damping.
5. Device in accordance with Claims 1 to 4, characterised in that the microprocessor can be operated from a remote control.
6. Device in accordance with Claim 1 to 5, characterised in that digital filters are provided to smooth the ripples from the pump.
7. Device in accordance with Claim 1 to 6, characterised in that the control valve (4) is fitted with a direct current drive, with or without feedback.
8. Device in accordance with Claims 1 to 6, characterised in that the control valve (4) is equipped with a stepping motor with or without feedback.
9. Device in accordance with Claims 1 to 8, characterised in that the mixing system can be activated for stationary use from a fire control centre.
10. Use of a device in accordance with Claim 9 in sprinkler installations.
11. Use of a device in accordance with Claim 9 in spray flooding installation.
12. Use of a device in accordance with one of the Claims 1 to 8 in fire engines.

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