FR2888639A1 - Gas e.g. carbon dioxide, distribution installation securing method, for fast food industry, involves mechanically detecting leakage of gas in distribution conduit, and controlling stop of gas circulation in conduit - Google Patents

Abstract

The method involves mechanically detecting a leakage of gas in a distribution conduit (3) connected between a compressed gas cylinder (2) and a carbonation apparatus (4). The stop of gas circulation in the distribution conduit is controlled using a flow circuit breaker (20) when the leakage of the gas is greater than a predetermined value, where the predetermined value is equal to three percentage of ventilation flow of a room (1). An independent claim is also included for a gas distribution installation disposed in a room.

Description

The present invention relates to a method for securing a

  distribution installation for a gas presenting a potential risk to the health of persons, by nature and / or because of its concentration, placed in premises frequented by the public, and to a distribution facility

gas thus protected.

  Gas distribution networks are used to store a large quantity of gas and distribute it on demand at one or more distribution stations. The gas thus flows through a set of pipes from a container located inside or outside the premises to the final distribution points where it is used.

  Such facilities are very commonly used in fast food catering for the distribution of carbon dioxide to beverage carbonation apparatus. As a result, the safety of personnel and possibly the public should be ensured in the event of a carbon dioxide leak. In the case of carbon dioxide, for example, the occupant exposure limit value is a concentration of 3% by volume.

  Detecting a carbon dioxide leak and securing the facility are therefore important aspects of carbon dioxide distribution, especially in public places. Of course, this aspect does not only concern the distribution of carbon dioxide but can be extended to any gas presenting a potential risk for the health of the people.

  Currently, two methods are mainly used to ensure the safety of such an installation, namely the detection of the concentration of carbon dioxide in a room, and distribution in ventilated sheath.

  The detection of carbon dioxide is based on the use of detectors fitted to each room of a room and connected to a central control unit able to control the stop of the distribution when the concentration of carbon dioxide exceeds the authorized threshold. One of the main disadvantages of this method is its installation cost. Indeed, the price of a carbon dioxide detector is high, and this cost must be multiplied by the number of parts to be controlled. In addition, these devices require significant maintenance and need a source of electrical power to operate.

  The distribution under ventilated sheath makes it possible to partially answer the cost problem. This solution consists in passing the distribution lines inside a ventilated duct connected to the outside air where any leakage gases are rejected. This method, however, has significant disadvantages, namely, a lack of protection at the final distribution point since the distribution lines must leave the sheath, maintenance and close monitoring of the sheath, and a lack of warning and significant waste in case of permanent leakage. In addition, the sheath must meet many safety standards, including fire standards, which increase its cost.

  The purpose of the present invention is to overcome the disadvantages mentioned above and for that purpose consists in a method of securing a gas distribution installation presenting a potential risk for health, by nature and / or because of its concentration, disposed in a room frequented by the public, and comprising at least one pipe connecting at least one source of said gas to at least one dispensing apparatus, characterized in that it comprises the steps of: - mechanically detecting a gas leak in the conduct; - Control the flow of gas in the pipe when the leakage rate is greater than a predetermined value.

  Local expression frequented by the public must be understood extensively and includes the movement of employees, customers and others.

  The term gas source refers, inter alia, to a refillable or replaceable tank, and to a town gas distribution type supply.

  Thus, by providing a mechanical detection of a gas leak, it is possible to control the entire pipe with a single equipment. The cost of installation is greatly reduced and maintenance is facilitated. In addition, a mechanical control does not require power supply. Such mechanical control also makes it possible to maintain active monitoring of the distribution pipe and has high reliability. The leak rate is measured by difference from an expected flow value. In fact, the consumption of the user devices under normal conditions is known, therefore an excess flow rate measured with respect to this expected flow rate is equivalent to the leakage rate.

  Advantageously, the predetermined value is a percentage of the ventilation rate of the room. Preferably, the predetermined value is equal to 3% of the ventilation rate of the room. In fact, since the ventilation already allows the removal of stale air, any accumulation of gas that would exceed the limit value set by the regulations should be prevented. By cutting the gas supply when the leakage rate, that is to say the excess flow compared to a flow rate under normal conditions, is greater than 3% of the ventilation rate, this accumulation is prevented. This percentage may of course be adapted according to the ventilation rate and the potential danger that the gas represents.

  Preferably, the mechanical detection step of the leak and the step of stopping the flow of gas in the pipe are performed simultaneously via a mechanical flow circuit breaker. A circuit breaker is of low cost and makes it easy to secure the gas distribution by measuring an excess flow. Indeed, beyond a limit value of flow, the circuit breaker closes the pipe.

  Advantageously, the method comprises an additional step aimed at triggering a visual and / or audible alarm.

  The present invention also relates to a distribution facility for a gas presenting a potential risk to health, by nature and / or because of its concentration, disposed in a room frequented by the public and comprising at least one gas source. adapted to deliver said gas to at least one user device via at least one pipe, characterized in that the pipe is equipped with a mechanical flow control means adapted to control pipe closure means when the leakage rate is greater than a predetermined value.

  Advantageously, the predetermined value is a percentage of the ventilation rate of the room. Advantageously, this percentage is 3%.

  Preferably, the mechanical control means and the closing means are made using a flow circuit breaker. Advantageously, the mechanical control means comprises a manually resettable locking means and can be connected to a visual and / or audible alarm device.

  The present invention is primarily intended for a carbon dioxide distribution installation but is not limited to the distribution of this gas, any gas presenting a risk to the health of the persons being targeted by this invention.

  The implementation of the invention will be better understood with the aid of the detailed description which is set out below with reference to the appended drawing in which: FIG. 1 is an overall diagram of a distribution installation of carbon dioxide.

  Figure 2 is a longitudinal sectional view of a flow switch installed in the installation of Figure 1, in the open position to circulate carbon dioxide.

  Figure 3 is a cross-sectional view of the flow switch of Figure 2 in the closed position blocking the passage of carbon dioxide.

  A carbon dioxide distribution installation secured by the invention is shown in FIG. 1. Such an installation is disposed in a dedicated room 1 and comprises a source of carbon dioxide in the form of a bottle 2 of rechargeable compressed gas capable of delivering carbon dioxide via a distribution line 3 to one or more dispensing devices, for example a carbonation apparatus 4 for the preparation of carbonated beverages, located inside a local frequented by the public.

  In addition to the distribution line 3, the bottle 2 is connected, on the one hand, to a supply line 5 intended to allow its refilling from an external filling terminal 6, and on the other hand, to an exhaust pipe 7 directed towards an external vent.

  The carbon dioxide distribution installation also comprises a backup bottle 8 connected to the distribution pipe 3 via a bypass box 9 allowing, for example, to switch on this emergency bottle 8 during the refill of the main bottle 2.

  In order to secure the distribution of carbon dioxide and to prevent any leakage of gas downstream of the bottle 2, that is to say in particular at the level of the carbonation apparatus 4 and the distribution pipe 3, this The last is equipped with a flow switch 20, shown in detail in FIGS. 2 and 3, as well as a non-return valve 10 arranged between the flow switch 20 and the branching box 9.

  In addition, the main gas distribution devices, namely the bottle 2 and the circuit breaker 20, can be equipped with sensors (not shown) connected to a signal box 12 to inform those present in case of incident.

  This circuit breaker 20 comprises an outer housing 21 delimiting an interior space and which comprises, on the one hand, an inlet 22 intended for the inlet of the gas under pressure, in this case the carbon dioxide coming from the bottle 2 and on the other hand, an outlet 23 intended for the exit of the gas towards the carbonation apparatus 4. A cover 24 closes the housing 21, said cover having in its center a channel 25 passing therethrough along a longitudinal axis substantially vertical.

  The interior space is divided into an upstream chamber 26, into which the inlet 22 opens, and a downstream chamber 27, into which the outlet 23 opens, by a separating element 28 of substantially cylindrical shape. This separation element 28 is traversed at its center by a channel 29 allowing the communication between the upstream chamber 26 and the downstream chamber 27. The peripheral sealing of the separation element 28 with the housing 21 is provided by a mounted seal 30 in a peripheral gorge.

  The upstream chamber 26 houses a piston 31 comprising a cylindrical head 31a and a rod 31b, this piston being able to slide along a longitudinal axis of the separating element 28 between an open position in which it is separated from the element 28 and allows the communication between the upstream chamber 26 and the downstream chamber 27, and a closed position in which the head 31a obstructs the channel 29 of the separation element 28 and thus prevent the passage of carbon dioxide from the upstream chamber 26 to the downstream chamber 27. The sealing of the closure is provided by a peripheral seal 32 located at the edge of the head 31a. It should be noted that the longitudinal axis of the separating element 28 merges with the axis of the channel 25 of the cover 24.

  The guide of the piston 31 is provided by the rod 31b sliding inside a non-through channel 33 of the outer casing 21.

  More specifically, the piston 31 is mounted against a spring 34 passing through the channel 29 to bear on the cover 24 so as to push the piston 31 in its open position.

  Furthermore, a cylindrical rod 35 is inserted through the channel 25 of the lid 24, said rod 35 having a first end terminated by a tip 36 and a second end on which a push button 37 is mounted mounted on a spring 38 bearing on the cover 24. This rod 35 has a length sufficient to come into contact with the piston 31 and push it into the open position when the push button 37 is depressed.

  In operation, the carbon dioxide enters the circuit breaker 20 through the inlet 22. The gas then flows from the upstream chamber 26 to the downstream chamber 27 before exiting the flow circuit breaker 20 through the outlet 23 to supply the carbonator 4.

  When an operator uses the carbonator 4 in the absence of any gas leakage on the network downstream of the circuit breaker 20, the pressure difference on either side of the piston 31 is small enough that the The spring 34 exerts sufficient force to hold the piston 31 in its open position, thereby allowing the carbon dioxide to circulate. Of course, when the carbonator 4 is unused, the pressures on either side of the piston are balanced and the spring also maintains the channel 29 open. It will be appropriate to choose a spring 34 having a stiffness adapted according to the flow rate of carbon dioxide desired during normal operation.

  If there is a leak in the network, the flow of carbon dioxide increases. As a result, the pressure in the downstream chamber 27 decreases sharply and the difference in pressures exerted on either side of the piston 31 increases. The carbon dioxide then exerts a higher pressure upstream of the head 31a, this pressure tending to push the piston 31 towards its closed position. The force required to maintain the piston 31 in its open position against the pressure exerted in the upstream chamber 26 is therefore increased accordingly. Beyond a certain pressure difference, the theoretical return force necessary to oppose the pressure forces so as to keep the piston 31 open is greater than the actual force exerted by the spring 34, which causes the closing of the channel 29 by the head 31a of the piston 31. The carbon dioxide no longer circulates through the network and its distribution to the carbonator 4 is stopped.

  The spacing between the piston 31 and the separation element 28 as well as the stiffness of the spring 34 makes it possible to adjust the sensitivity of the circuit breaker 20 as a function of a desired leakage flow rate value.

  Advantageously, these parameters are calculated so that the delivery of carbon dioxide is stopped when the leakage rate exceeds three percent of a ventilation rate of the local frequented by the public.

  The release of carbon dioxide thus stopped, it is proceeded to the repair of the leak.

  Once the leak has been repaired, the circuit breaker 20 can be brought back manually to the open position, allowing the carbon dioxide to flow towards the carbonation apparatus 4. To do this, the operator presses the pushbutton 37. By doing so, the rod 35 slides through the channel 25 of the lid 24 and its tip 36 forces the piston 31 into its open position. The carbon dioxide can again pass from the upstream chamber 26 to the downstream chamber 27 and the balance of pressures on either side of the piston is restored, which allows the spring 34 to keep the piston 31 open. The operator can then release the push button 37 which, under the effect of the spring 38, returns the rod 35 to its initial position set back from the piston 31.

  Although the invention has been described in connection with particular embodiments, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims (10)

  1. A method of securing a gas distribution plant presenting a potential risk to health, by nature and / or because of its concentration, disposed in a room frequented by the public, and comprising at least one pipe ( 3) connecting at least one source (2) of said gas to at least one dispensing apparatus (4), characterized in that it comprises the steps of: - mechanically detecting a gas leak in the pipe; - Control the flow of gas in the pipe when the leakage rate is greater than a predetermined value.   2. Method according to claim 1, characterized in that the predetermined value is a percentage of the ventilation rate of the room.   3. Method according to claim 2, characterized in that the predetermined value is equal to 3% of the ventilation rate of the room.   4. Method according to any one of claims 1 to 3, characterized in that the mechanical detection step of the leak and the step of stopping the flow of gas in the pipe are performed simultaneously via a mechanical flow circuit breaker (20).   5. Method according to any one of claims 1 to 4, characterized in that it comprises an additional step for triggering a visual and / or audible alarm.   6. Installation for the distribution of a gas presenting a potential risk to health, by nature and / or because of its concentration, placed in a room frequented by the public and comprising at least one source (2) of gas capable of delivering said gas to at least one user device (4) via at least one pipe (3), characterized in that the pipe is equipped with a mechanical flow control means adapted to control closure means of driving when the leakage rate is greater than a predetermined value.   7. Installation according to claim 6, characterized in that the predetermined value is a percentage of the ventilation rate of the room.   8. Gas distribution system according to any one of claims 6 or 7, characterized in that the mechanical control means and the closing means are made using a flow switch (20).   9. Installation according to any one of claims 6 to 8, characterized in that the mechanical control means comprises a manual reset locking means.   10. Gas distribution installation according to any one of claims 6 to 9, characterized in that the mechanical control means is connected to a device (12) of visual and / or audible alarm.