EP2154104B1

EP2154104B1 - Plant for fluid distribution in a workshop

Info

Publication number: EP2154104B1
Application number: EP08425492A
Authority: EP
Inventors: Giuseppe Virga; Elio Baschieri; Lino Di Betta
Original assignee: Filcar SpA
Current assignee: Filcar SpA
Priority date: 2008-07-21
Filing date: 2008-07-21
Publication date: 2011-11-30
Anticipated expiration: 2028-07-21
Also published as: EP2154104A1; ATE535491T1

Abstract

A plant for fluid distribution in a workshop comprising: a storage tank (2) for a workshop fluid; a delivery station (3); a distribution network (4) extending between the tank (2) and the delivery station (3); a pump (5) in fluid communication with the tank (2) to draw fluid from the tank (2) and admit it into the distribution network (4); first detecting means (10) adapted to generate at least one signal (SA) representative of the activation state of the pump (5); second detecting means (11) adapted to generate a signal (SE) representative of the activation state of the delivery station (3); and a management unit (12) adapted to receive and process the signals (SA, SE) generated by the first and second detecting means (10, 11), so as to generate an alarm signal (SW) in the presence of an active pump (5) when the delivery station (3) is inactive.

Description

The present invention relates to a plant for distribution of fluids in a workshop, also referred to as "workshop fluids".
By "workshop fluids", in the context of the present invention it is intended fluids (gases and liquids) used in repair, maintenance and construction of motor-vehicles.
Examples of workshop fluids are oil for motors, oil for braking systems, oil for differential gears, oil for gearbox, liquid for radiators, windshield washer liquid and the like.
The present invention can be used at the inside of mechanical repair workshops, in assistance centres and motor-vehicle production lines.
Known are in particular plants for fluid distribution in workshops comprising one or more storage tanks containing different workshop fluids and connected to one or more delivery stations though a distribution network. A plant having the features of the preamble of patent claim 1 is known from EP 1 880 975 A1 .
The fluid is sent to the delivery stations through one or more pumps carrying out transfer of same from the tank to the distribution network and then to the delivery station.
Each delivery station is provided with a dispensing device for each type of fluid and is placed in close proximity to the work station of each technician.
In particular, the pump keeps the fluid at the inside of the distribution network under pressure, so that as soon as a dispensing device is operated the workshop fluid is promptly delivered.
In this way, the fluid required by each operator is immediately available and ready for delivery.
However, the plants for delivery of workshop fluids briefly described above have some drawbacks.
In fact, it may happen that in the distribution network leaks or losses of fluid may occur, due for example to the highly aggressive character of the fluid (as in the case of the fluid in braking systems which is corrosive).
Under these circumstances, fluid leak goes on until the plant is switched off, because said fluid is always maintained under pressure inside the distribution network.
Should fluid leak take place at locations that cannot be inspected, such as the inside of partitions, or should nobody notice liquid stains or pools on the ground, situations that are potentially very dangerous can be generated.
In fact the leaked fluid, if it is inflammable, can catch fire, or the liquid can be absorbed by the ground and pollute the surrounding environment, or it can also release toxic volatile substances.
Further disadvantages resulting from losses of the above mentioned fluid can be represented by the cost of the escaped fluid (which therefore can be no longer used), damages to the plant structures and equipment, as well as to the vehicles that are close to the plant itself.
In this context, the technical task of the present invention is to make available a plant for fluid distribution in workshop which is capable of substantially obviating the mentioned drawbacks.
Within the scope of this technical task, it is an important aim of the invention to propose a plant for distribution of workshop fluids capable of preventing situations that can be potentially dangerous due to fluid leak.
The mentioned technical task and the specified aim are substantially achieved by a plant for fluid distribution in a workshop according to one or more of the appended claims.
Description of a preferred but not exclusive embodiment of a plant for fluid distribution in a workshop in accordance with the invention is now given by way of non-limiting example and illustrated in the accompanying drawings, in which:

Fig. 1 diagrammatically shows a plant for fluid distribution in a workshop according to the present invention; and
Fig. 2 is a diagrammatic block representation of some parts of the plant seen in Fig. 1.

With reference to the drawings, a plant for fluid distribution in a workshop in accordance with the invention has been generally identified by reference numeral 1.
As mentioned above, by "workshop fluids" it is intended in the context of the present invention, fluids (gases and liquids) used in repair, maintenance and construction of motor-vehicles.
Examples of workshop fluids are oil for motors, oil for braking systems, oil for differential gears, oil for gearbox, liquid for radiators, windshield washer liquid and the like.
Plant 1 comprises at least one storage tank 2 for a workshop fluid, at least one fluid delivery station 3, a distribution network 4 extending between the tank 2 and the delivery station 3 and a pump 5 in fluid communication with tank 2 to draw liquid therefrom and admit it into the distribution network 4.
Advantageously pump 5 is associated with a control system 13 adapted to manage switching on and off of said pump 5.
Tank 2 can be a drum of a capacity of about 200 litres (in case of plants of small sizes), or a reservoir of a capacity of about 1000 litres (in case of plants of medium-big sizes).
The invention at all events can advantageously be used for plants provided with tanks of any capacity.
Preferably tank 2 is installed on suitable supports (not shown) and possibly underground.
Preferably, tank 2 is a double-wall tank to reduce the likelihood of accidental fluid escape from the tank. Preferably, tank 2 comprises a level meter 25 to stop suction by pump 5, through the control system 13 for example, should tank 2 be completely empty, thus avoiding introduction of air bubbles into the distribution network 4.
Preferably, plant 1 comprises a plurality of tanks 2, each of them containing a different type of workshop fluid.
Each tank 2 is in fluid communication with a dedicated distribution network 4 (as diagrammatically shown in Fig. 1).
Should several distribution networks 4 be provided, each distribution network 4 is not in fluid communication with the others.
Each distribution network 4 comprises a main duct 6 and a plurality of branching-off ducts 7 connected, mutually in parallel, to the main duct 6.
For instance, the main duct 6 consists of rigid steel pipes fastened to the wall of the room wherein plant 1 is to be housed.
Alternatively, the main duct 6 consists of flexible hoses laid under the floor or at the inside of wall raceways.
The branching-off ducts 7 are adapted to feed the delivery stations 3 by connecting them to the main duct 6.
Preferably, the branching-off ducts 7 comprise a flexible end portion 8, so that the branching-off ducts 7 can be extended or shortened depending on requirements, i.e. depending on the position at which the workshop fluid is to be delivered.
Preferably, the flexible portion 8 (diagrammatically shown in Fig. 1) is rolled in a mechanical coiler 23 for flexible hoses.
Each delivery station 3 is preferably located at a distal position relative to tanks 2; in particular, each delivery station 3 is placed close to a work area (not shown) where the vehicle remains during the production, maintenance, repair operations.
Each delivery station 3 comprises one dispensing gun 9 connected to the distribution network 4. In more detail, the dispensing gun 9 is connected to the flexible end portion 8 of the branching-off duct 7, in such a manner that the latter, by the dispensing gun 9, can directly reach the vehicle tank on which the workshop fluid is to be used.
Each dispensing gun 9 comprises a handgrip and a switching-on lever for fluid delivery.
Preferably, each dispensing gun 9 further comprises a lock button to stop the dispensing gun to the delivery position to enable delivery of fluid without requiring the gun being gripped, and a spout provided with a dripping-preventing check valve to avoid the workshop fluid from dripping when delivery is over.
Preferably, each dispensing gun 9 is equipped with a litre-counter device 21. The litre-counter device 21 comprises a hollow body passed through by the flow of the workshop fluid to be dispensed which drives a pair of idler gears in rotation, the number of revolutions of which is detected by an encoder.
It is to be noted that the litre-counter device 21 can also be positioned upstream of the dispensing gun 9, and in particular between the branching-off duct 7 and the flexible portion 8.
In addition or as an alternative to each delivery station 3, a metering cock 22 can be provided which is equipped with a leverage for activation and adjustment, to enable an operator to fill a graduated decanter by which the fluid is poured off into the tank of the vehicle on which the fluid is used.
Generally, each delivery station 3 has an operating end for delivery of the workshop fluid.
The dispensing gun 9 and metering cock 22 are examples of this operating end.
In a first embodiment, pump 5, one for each tank 2, is a pneumatic pump.
Preferably, each pump 5 is a single-acting or double-acting piston pump.
The piston pump 5 (not shown in detail) comprises a propelling plunger which is moved with a reciprocating motion within the first cylinder.
The propelling plunger is driven by a compressed-air source of constant pressure.
The propelling plunger is mechanically connected and drives a piston that is moved with a reciprocating motion within a second cylinder.
The cylinder is provided with a suction duct, in fluid communication with tank 2, and with a delivery duct, in fluid communication with the distribution network 4 and therefore with the delivery stations 3 by means of the main duct 6 and the branching-off ducts 7.
The propelling plunger drives the piston with a reciprocating motion, which piston draws the fluid from the suction duct and feeds it under pressure to the delivery duct.
Through closure of the delivery duct, the force exerted by the fluid within the second cylinder quickly becomes equal to the thrust supplied by the compressed-air tank and acting on the propelling plunger, stopping the pump.
In particular, a low pressure in the delivery duct, determined by delivery of fluid from a delivery station 3, operates pump 5, while a high pressure in the delivery duct, produced by non-use of the delivery stations 3, stops pump 5.
In a further embodiment, pump 5 is an electric pump. This electric pump can be of the fixed-displacement type or of the variable-displacement type. In the first case, pump 5 is able to substantially keep the flow rate of the delivered fluid constant, and therefore generates the necessary pressure to keep the nominal flow rate.
Therefore, when no delivery takes place from at least one delivery station 3, pressure generated by the electric pump 5 has a tendency to increase in an uncontrolled manner.
It is then provided that a first pressure switch be calibrated to a first threshold pressure Pmax, and the control system 13 of pump 5 switches the pump off when this limit value is reached.
A second pressure switch is set to a second threshold pressure Pmin enabling restarting of pump 5 when, following delivery at one or more delivery stations 3, pressure in the fluid-operated circuit falls under the predetermined limit value.
The control system 13 of pump 5 can therefore have a first input connected to the first pressure switch, and a second input connected to the second pressure switch, operating a remote control switch.
Signals received on the first and second inputs will be respectively used as switching-off and switching-on commands of pump 5, that will be therefore interlocked with said remote control switch. In other words, depending on the signals received on the first and second inputs, the remote control switch carries out switching on/off of pump 5.
In addition, an auxiliary contact which is representative of the activation state of pump 5 can be obtained from the remote control switch; use of this auxiliary contact will be explained in the following.
As mentioned above, pump 5 can be an electric variable-displacement pump, in particular provided with a pressure-driven system for automatic adjustment of the flow rate.
In this case, pump 5 can be a vane pump comprising a collector ring shiftable between two positions: in a first position the ring is substantially concentric with the vane rotor of the pump (zero-flow rate condition), while in a second position the collector is tangent to the rotor (maximum-flow rate condition).
The collector displacement is governed by a spring tending to push the collector itself to the second position, which spring is countered by the generated delivery pressure tending to push the ring to the first position. If pressure in the fluid-operated circuit is low or zero, the spring thrust prevails and the pump generates the maximum flow rate.
Increasing of the flow rate gives rise to an increase in the flow resistance and consequently in the delivery pressure; this pressure increase pushes the collector towards the first position and there is a flow rate decrease.
If pressure goes on increasing, the collector ring continues its displacement towards the first position, until the condition of substantial concentricity with the rotor is reached and the generated flow rate is reduced to zero.
The maximum pressure required for reducing the pump flow rate to zero substantially depends on the force of said compensation spring, on the preloading of which it is possible to operate in order to calibrate the system.
Unlike the above mentioned fixed-displacement pump, switching on/off of the electric motor is not required in order to keep the plant to a given pressure range; in fact, if the variable-displacement pump is maintained always switched on, the flow rate goes to zero in an automatic manner in the absence of active user bases.
On the contrary, when one or more user bases or delivery stations 3 start delivery, the pressure drop causes the force generated by the compensation spring to prevail so that the collector ring is brought back to the tangent position and, as a result, there is an increase in the generated pressure until the system reaches a new balance condition.
Advantageously, plant 1 comprises first detecting means 10 (diagrammatically shown in Fig. 1) acting on each pump 5 and adapted to generate at least one signal SA representative of the activation state of pump 5 (Fig. 2).
In particular, the first detecting means 10 is suitable to determine whether pump 5 is active, i.e. whether pump 5 is transferring fluid from tank 2 to the distribution network 4.
The first detecting means 10, preferably in the case of a pneumatic piston pump 5, can consist of a reed sensor (not shown in detail) acting on the propelling plunger or piston of pump 5 to detect the plunger or piston movement.
In more detail, the reed sensor can be a (normally open) reed switch that closes in the presence of a magnetic field generated by the propelling plunger or piston stroke, closing a circuit adapted to generate said activation signal SA.
In more detail, the reed sensor can comprise a magnetic portion (a permanent magnet, for example) and a sensitive portion (provided with one or more reeds of metal material, for example).
For instance, the magnetic portion is substantially integral with the propelling plunger or the piston, while the sensitive portion is substantially integral with the pump body and/or the tank.
At all events, the magnetic portion is provided to be substantially integral with the pump body and/or the tank, while the sensitive portion can be substantially integral with the propelling plunger or the piston.
Depending on whether the sensitive portion or magnetic portion are close to or far from each other, movement of the propelling plunger and the piston can be detected, so that the pump activity is detected.
Depending on this detection, said activation signal SA is advantageously generated.
The first detecting means 10, preferably when pump 5 is an electric fixed-displacement pump, can comprise a connection to said pump 5, to detect a switched on/off state of same.
More particularly, the first detecting means 10 can comprise a connection to a remote control switch, such as the one briefly described above, acting on pump 5 to selectively supply the same with electric power.
The first detecting means 10, preferably if pump 5 is an electric variable-displacement pump, can comprise a current sensor, in particular of the Hall-effect type, to determine the current absorbed by the pump motor and, depending on this absorption, determine the activation condition of pump 5.
Generally, the first detecting means 10 can comprise a vacuostat device associated with pump 5 to detect a vacuum of same on sucking.
Plant 1 further comprises second detecting means 11 (diagrammatically shown in Fig. 1) adapted to generate a signal SE representative of the activation state of at least one delivery station 3. This activation state can be directly or indirectly connected to the fluid delivery at the delivery station 3.
Preferably, the second detecting means 11 can comprise a sensor associated with the above mentioned coiler 23 to roll the flexible portion 8 of the branching-off duct 7 of the delivery station 3.
In particular, this sensor is able to detect an operating dispensing condition or a rest condition of said flexible portion 8.
Practically, in the rest condition the flexible portion 8 is substantially fully rolled-up around its coiler 23, while in the operating dispensing condition the flexible portion 8 is at least partly and preferably fully unrolled.
In this case the second detecting means 11 can for instance comprise a sensor of the reed type, suitably associated with coiler 23 to detect a rotation of same.
The second detecting means 11 can also comprise a microswitch contact associated with coiler 23, to detect a rotation of same and/or to detect when coiler 23 is at an end-of-stroke position (a fully rolled condition or a fully unrolled condition).
The second detecting means 11 can comprise a sensor suitable to detect whether an operating end of the delivery station 3 is at an operating dispensing position or at a rest condition.
This operating end preferably consists of said dispensing gun 9.
The dispensing gun 9 is in a rest condition when it is for example positioned in a drop-collecting housing, while it is in the operating condition when pulled out of said housing.
The second detecting means 11 can then consist of a contact sensor (e.g. a microswitch) suitably mounted on said housing in order to determine the presence or not of the dispensing gun 9.
Preferably, the second detecting means 11 acts on each dispensing gun 9 and is adapted to determine operation of same so as to generate the SE signal representative of the fluid delivery.
Preferably, the second detecting means 11 comprises a flowmeter (not shown) detecting passage of fluid through the dispensing gun 9.
Preferably this flowmeter is coincident with the litre-counter device of the above described dispensing gun 9.
Alternatively, the second detecting means 11 comprises a device for detecting operation of the activation lever of the dispensing gun 9.
In the same manner, the second detecting means 11 can be applied to the activation and adjustment leverage 22a of the metering cock 22 possibly being part of the delivery station 3, for the purpose of generating said signal SE.
Preferably, the second detecting means 11 can comprise a connection to a user interface 14 to be better described in the following.
Plant 1 comprises a management unit 12 (diagrammatically shown in Fig. 1) adapted to receive and process signals SA, SE generated by the first detecting means 10 and the second detecting means 11 in order to generate an alarm signal SW, should pump 5 be active and the delivery unit 3 be switched off.
In this way, potentially dangerous situations due to leak of the workshop fluid can be advantageously prevented.
In fact, the alarm signal SW is generated should pump 5 be active and should therefore admit fluid into the distribution network 4 without any delivery station 3 being actually dispensing fluid.
This means that the alarm signal SW is generated when fluid leak is occurring in the distribution network 4.
It is to be noted that, as said above, pump 5 admits fluid into the distribution line 4 when pressure in the delivery duct is low. This situation occurs both when the delivery station 3 is dispensing fluid, and when in the distribution network 4 there is a leak from which the fluid escapes.
Preferably, the alarm signal SW generated by the management unit 12 is adapted to switch pump 5 off preferably stopping feeding of same. This feeding interruption advantageously takes place by means of said control system 13 of pump 5.
In particular, if pump 5 is of the pneumatic type, the alarm signal SW causes an interruption in the pneumatic feeding to pump 5.
If pump 5 is an electric pump, the alarm signal SW causes an interruption in the electric feeding to pump 5.
Alternatively, a solenoid valve (not shown) interlocked with the alarm signal WS can be active on the delivery duct of pump 5, in such a manner that activation of same closes the delivery duct, immediately stopping pump 5.
Preferably, the alarm signal SW therefore ultimately aims at inhibiting admission of fluid into the distribution network 4.
Alternatively or in combination with the above, the alarm signal SW generated by the management unit 12 is able to generate an acoustic/visual indication concerning the fact that an undesired leak of workshop fluid is occurring. This acoustic/visual indication can be carried out from an illuminated display lamp and an acoustic siren (both not shown).
Preferably, the fact that the alarm signal SW either causes switching-off of pump 5, or merely supplies an acoustic/visual signal to the operator, can depend on the frequency with which signal SA is received by the management unit 12.
More particularly, if signal SA is transmitted to the management unit 12 in a substantially continuous manner or at all events at a frequency greater than a predetermined threshold, it means that pump 5 is substantially always active (or in any case is switched on very frequently) and therefore is feeding a leak of very important amount. In this case therefore the alarm signal SW will directly switch pump 5 off.
If on the contrary, signal SA is transmitted to the management unit 12 less frequently, i.e. at a lower frequency than said predetermined threshold, it means that there is a leak of less amount (there is a dripping connection or a faulty dispensing gun, for example) and it is therefore sufficient to provide an acoustic/visual signal to the operator, without switching pump 5 off.
As mentioned above, the delivery station 3 comprises a user interface 4. The user interface 14 is adapted to generate an enabling signal SO of the delivery station 3 on identification of an operator. This signal SO is transmitted to a solenoid valve 24 interposed between the branching-off duct 7 and the flexible portion 8 that on receipt thereof enables the delivery station 3.
A non-reception of the enabling signal SO makes the delivery stations inactive. In this way only a qualified and identified operator can be enabled to use of plant 1.
Advantageously, the enabling signal SO can be also sent to the management unit 12, to which the user interface 14 is preferably connected.
The enabling signal SO can therefore constitute said signal SE representative of the activation state of the delivery station 3.
The management unit 12 can use the enabling signal SO, in combination with or in place of the above mentioned signal SE, in order to decide whether the alarm signal SW is to be generated or not.
Therefore, as above stated, the second detecting means 11 can comprise a connection with said user interface 14.
Preferably, plant 1 (Fig. 2) comprises respective transmitters 15a connected to the second detecting means 11, and at least one respective transmitter 15b connected to the first connecting means 10.
Plant 1 further comprises at least one first and one second receiver 16a, 16b connected to the management unit 12.
The management unit 12 further comprises at least one transmitter 17 to transmit the alarm signal SW to pump 5.
Pump 5 is associated with a receiver 18 to receive the transmitted alarm signal SW and be switched on.
For instance, the alarm signal SW can be provided to pump 5 through said control system 13.
Signal SE, representative of the activation state of each delivery pump 3, is transmitted by the respective transmitter 15a and received by the first receiver 16a.
Signal SA, representative of the activation state of pump 5, is transmitted by transmitter 15b and is received by the second receiver 16b. Preferably, one or more of said transmitters/receivers communicate via wireless technology.
In the preferred embodiment, at least transmitters 15a associated with the second detecting means 11 and the first receiver 16a associated with the management unit 12 mutually communicate via wireless technology.
Connection between the management unit 12 and pump 5 and in particular the control system 13, can also be of the wired type.
The user interface 14 too can communicate with the management unit 12 either through wireless signals or through a wired connection and comprises a respective transmitter 19 communicating with a receiver 20 of the management unit 12.
Receivers 16a, 20 of the management unit 12 can be integrated into a single receiving device.
The invention achieves the intended purposes.
In fact, the alarm signal SW is generated when pump 5 is active and therefore admits fluid into the distribution network 4 without any delivery station 3 being really in an activated condition. This means that the alarm signal SW is generated when fluid leak is taking place in the distribution network 4.
This alarm signal enables the operators to be warned about the occurrence of fluid leak and/or to immediately stop the pump.

Claims

A plant for fluid distribution in a workshop comprising at least one storage tank (2) for a workshop fluid, at least one delivery station (3) to dispense said fluid, a distribution network (4) extending between said tank (2) and said delivery station (3) to bring them into fluid communication, a pump (5) in fluid communication with said tank (2) to draw fluid from said tank (2) and admit it into said distribution network (4), characterised in that it comprises first detecting means (10) associated with said pump (5) and adapted to generate at least one first signal (SA) representative of the activation state of the pump (5), second detecting means (11) adapted to generate a second signal (SE) representative of the activation state of said delivery station (3), and a management unit (12) adapted to receive and process said first and second signals (SA, SE) generated by the first and second detecting means (10, 11) so as to generate an alarm signal (SW) in the presence of an active pump (5) when the delivery station (3) is inactive.
A plant as claimed in claim 1, wherein said alarm signal (SW) is adapted to switch said pump (5) off.
A plant as claimed in claim 1 or 2, wherein said alarm signal (SW) is adapted to inhibit admission of fluid into the distribution network (4).
A plant as claimed in anyone of the preceding claims, wherein said pump (5) is a pneumatic piston pump.
A plant as claimed in anyone of the preceding claims, comprising a control system (13) acting on said pump (5) and interlocked with said alarm signal (SW) to inhibit feeding to said pump (5).
A plant as claimed in anyone of claims 1 to 3, wherein said pump (5) is an electric pump.
A plant as claimed in claim 6, wherein said alarm signal (SW) is adapted to inhibit said pump (5) from being electrically fed.
A plant as claimed in anyone of the preceding claims wherein said second detecting means (11) comprises one or more of the following elements:
- a flowmeter placed in said delivery station (3) to determine fluid passage and delivery from said delivery station (3);

- a sensor associated with a coiler (23) for rolling a flexible portion (8) of a branching-off duct (7) being part of said delivery station (3), said sensor being suitable to detect an operating dispensing condition or a rest condition of said flexible portion (8);

- a sensor suitable to detect whether an operating end of said delivery station (3) preferably comprising a dispensing gun (9) or a metering cock (22) is in an operating dispensing position or in a rest position.
A plant as claimed in anyone of the preceding claims, wherein said first detecting means (10) comprises one or more of the following elements:
- a reed sensor acting on a propelling plunger of said pump (5) for detecting movement of said propelling plunger;

- a connection to a circuit of said electric pump (5) for detecting a switched on/off state of the latter;

- a Hall-effect current sensor associated with said pump (5), the latter being preferably a variable-displacement electric pump;

- a vacuostat associated with said pump (5) for detecting a vacuum of the latter on sucking.
A plant as claimed in claim 1, wherein said delivery station (3) comprises a user interface (14) adapted to generate an enabling signal (SO) for the delivery station (3) on identification of an operator.
A plant as claimed in claim 10, wherein said user interface (14) is connected to said management unit (12) to supply the latter with said enabling signal (SO), said enabling signal (SO) defining said signal (SE) representative of the activation condition of said delivery station (3).
A plant as claimed in claim 1, comprising at least one transmitter (15a) connected to said second detecting means (11), and at least one receiver (16a) connected to said management unit (12) for transmitting and receiving said signal (SE).
A plant as claimed in claim 12, wherein said transmitter (15a) and first receiver (16a) transmit and receive said signal (SE) via wireless technology.
A plant as claimed in anyone of the preceding claims, wherein said management unit (12) comprises at least one transmitter (17) for sending said alarm signal (SW); said pump (5) being associated with at least one receiver (18) for receiving said alarm signal (SW).
A plant as claimed in claim 1, comprising a plurality of delivery stations (3) connected, mutually in parallel, to said tank (2) and located at remote positions relative to said tank (2).
A plant as claimed in claim 1, wherein said signal (SW) is a notification signal adapted to indicate a malfunction in said plant (1).
A plant as claimed in claim 1, wherein said alarm signal (SW) switches said pump (%) off and/or provides a malfunction signal as a function of a frequency at which said signal (SA) representative of the activation state of the pump (5) is transmitted to said management unit (12).