GB2155906A - Method and apparatus for supplying or dispensing a pressurised fluid - Google Patents

Abstract

Apparatus for spray or aerosol treating an interior space of a building comprises a bulk container 1 for a treating agent dissolved in liquid carbon dioxide, a metering container 11 and a piping system 9 including spray outlets 10; a single two position valve 7 isolates the piping system while admitting fluid from the bulk container 1 into the metering container 11 and then, after isolating the bulk container 1, admits fluid from the metering container 11 into the piping system 9. <IMAGE>

Description

SPECIFICATION Method and apparatus for supplying or dispensing a pressurised fluid This invention relates to the fumigation, deodorization or like treatment of building interiors by way of permanent installation in the building for that purpose. Typically, an installation of the kind in question comprises a bulk container holding a charge of propellant and treating agent, a piping system extending from that container throughout the building, outlet sprays at various points along the piping system and a, usually timer operated, control valve controlling the flow of mixed propellant and agent from the container to the spray outlets.

The invention is applicable to situations in which the propellant is a high vapour pressure liquid, for example, a fluorocarbon, hydrocarbon or liquefied carbon dioxide. The treating agent is mixed or dissolved in the propellant and the propellant serves not only to pressurize the bulk container to effect fluid flow therefrom but also, at the point of release from the outlet sprays, to reduce the fluid to the droplet form.

The treating agent may vary depending upon requirements. It may, for example, be a pesticide such as a mixture of pyrethrins and piperonyl butoxide, an insecticide such as 2,2-dichlorovinyl dimethyl phosphate or a deodorant such as lauryl methacrylate.

Existing installations are largely satisfactory when there is no malfunction of the apparatus but occasionally the valve may fail due, for example, to an electrical fault or the timer control equipment may malfunction permitting the valve to remain open for an overlong period. If such malfunction occurs, then all or excessive amounts of the fluid in the bulk container may be liberated into the building. In view of the nature of the treating agents, such excessive release of those agents may be harmful or even dangerous, especially if the building is occupied at the time of the event.

An object of the present invention is to reduce the likelihood of excessive release of fluid from the bulk container, which object is attained by the provision of a metering container and a single threeway valve which ensures that at no time is the bulk container in direct communication with the piping system.

According to one aspect the invention consists in apparatus for the spray or aerosol treatment of a building interior comprising a bulk container for a bulk quantity of treating fluid, being a treating agent dissolved or mixed in a high vapour pressure liquid propellant, a metering container for a unit charge of said fluid, a piping system with at least one spray outlet and a single change-over valve for controlling flow of fluid from the bulk container into the metering container and from the metering container to the piping system, said valve being such that in one position the bulk container is in communication with the metering container and the metering container is isolated from the piping system and, in another position the bulk container is isolated, and the metering container is in communication with the piping system.

According to a second aspect, the invention consists in a method of spray or aerosol treating the interior space of a building with a treating fluid, being a treating agent dissolved or mixed in a high vapour pressure liquid propellant, comprising the steps of admitting a unit charge of said fluid from a bulk container thereof into a sealed metering container, then sealing the bulk container, then admitting the fluid in the metering container into a piping system having at least one spray outlet in the space to be treated and then resealing the metering container in readiness for the next treatment.

By way of example, the above-described invention is described in more detail hereinafter with reference to the accompanying drawing which is a diagrammatic layout of an apparatus according to the first aspect of the invention.

In the illustrated apparatus the bulk container comprises a plurality (in this case four) of cylinders 1 each furnished with an emission control valve 2 and an open-bottomed eduction tube 3.

Valves 2 are pipe-connected (4) to a header or manifold 5. This has a single outlet 6 which opens to the intake port of 3-way valve 7. Valve 7 has a first outlet port connected to a branch pipe 8, and a second outlet port connected to a fluid-delivery pipe 9.

Valve 7 is of known construction and is operable so that its inlet 6 may be open to pipe 8 while pipe 9 is closed, or pipe 8 is open to pipe 9 while inlet 6 is closed, Pipe 9 leads to the point of use, in this instance an atomising nozzle 10.

Pipe 8 leads to a unit charge metering container 11. This container is normally closed except for its entrance 12 for pipe 8.

Measurement of a unit charge of fluid may be effected in several different ways. For example, metering container 11 may be made of such capacity that when the fluid in it reaches the pressure prevailing in vessel 1 it is holding a unit charge fluid increment. This would of course be satisfactory where container 1 is one normally kept under substantially constant pressure, or where the pressure declines with fluid usage, provided the amount of each charge is not critical.

Alternatively, metering container 11 and its content may be weighed so that when the total weight equals a selected amount, valve 7 is operated in response to halt fluid inflow from vessel 1. One way of doing this (as shown in the drawing) is to freely suspend container 11 on a spring 13 able to act in the manner of a spring balance. Suspension rod 14 may carry a striker 15 which, upon descent of rod 14 (due to the weight of fluid in the container) micro-switch 16 is activated to cause operation of valve 7 appropriately.

In use, valve 7 is first operated to charge metering container 11. This is done with pipe 9 closedoff. When container 11 is charged, valve 7 is reopened to open pipe 8 to pipe 9 while closing-off inlet 6.

The pressure in vessel 11 then suffices to send the charge into pipe 9 and so out of nozzle 10.

It will be seen from the foregoing that if the valve 7, for any reason, fails to operate, the worst result will be failure to issue a charge from nozzle 10. This can simply be used, to indicate the failure, by observation or by appropriate monitoring with or without automatic rectifying response.

If desired, the number of closures of microswitch 16 may be relied on to indicate when the number of operations is such as to bring the bulk container close to exhaustion. Micro-switch actuation may also be employed as a means of indicating a failure as aforesaid. As a further choice, switch 16 may be used as trigger (instead of conventional timing means) for causing the sequential operations of valve 7.

In the drawing, dotted arrows 17 indicated charging of container 11, and unbroken arrows 18 indicate discharging of that container.

A further point disclosed by our experiments, of which the present invention is the result, showed that in the prior art apparatus employing a plurality of cylinders as indicated at 1, there is a tendency for the several cylinders to become discharged unequally thus necessitating frequent cylinder replacement operations. We have found that this can be remedied, or extensively so, by so arranging the supply pipes 4 that their entrance points to manifold 5 (19) are placed equi-distantly from the single outlet 6.

In installations according to the invention utilising liquid carbon dioxide as the propellant, it has been found that the treating agent remains in solution in the liquid propellant notwithstanding gasification of some of the propellant whilst charging the metering container. Experiments have shown this to be the case in practice when quantities of fluid received by variously sized metering containers 11 range from as little as 30g to as much as 30kg.

During discharge to the piping system 9 and nozzle 10 the total time taken to completely discharge the fluid to atmosphere in aerosol form (discrete droplets in the range of 2-20 microns diameter) may be, say, 15 minutes. Throughout such discharge the pressure in the system remains substantially constant until the liquid propellant is exhausted. The pressure then drops to that of the gaseous CO2 which may take a further 30 minutes or so to exhaust from the metering container 11 ensuring that the piping system and spray nozzles are completely free of any treating agent which normally is retained in the liquid phase of the propellant.

The times quoted above are purely by way of example and will, of course, depend greatly in any particular installation upon the capacity of the metering container 11, the number, length and size of pipes in the pipe line system and the number of spray outlet nozzles.

It will be appreciated from the foregoing descripion that in its broadest aspect the invention provides a method of supplying metered quantities of pressurised fluid to a chosen location from at least one container thereof in isolation from said location, comprising the steps of admitting a unit charge of said fluid to a metering vessel, said vessel being isolated from said location, isolating the container from said vessel, placing the vessel in communication with said location to supply said unit charge to said location, and then isolating the vessel from said location and repeating the sequence of steps.

Claims (9)

1. Apparatus for the spray or aerosol treatment of a building interior comprising a bulk container for a bulk quantity of treating fluid, being a treating agent dissolved or mixed in a high vapour pressure liquid propellant, a metering container for a unit charge of said fluid, a piping system with at least one spray outlet and a single change-over valve for controlling flow of fluid from the bulk container into the metering container and from the metering container to the piping system, said valve being such that in one position the bulk container is in communication with the metering container and the metering container is isolated from the piping system and, in another position the bulk container is isolated, and the metering container is in communication with the piping system.

2. Apparatus according to claim 1, wherein said valve admits of a third position in which the bulk container, metering container and piping system are all isolated from each other.

3. Apparatus according to either of the preceding claims, wherein the metering container is resiliently mounted and movement of the container due to the weight of fluid in it is utilised to control the operation of the valve means.

4. Apparatus for spray or aerosol treating an interior space of a building substantially as described herein with reference to the accompanying drawings.

5. A method of spray or aerosol treating the interior space of a building with a treating fluid, being a treating agent dissolved or mixed in a high vapour pressure liquid propellant, comprising the steps of admitting a unit charge of said fluid from a bulk container thereof into a sealed metering container, then sealing the bulk container, then admitting the fluid in the metering container into a piping system have at least one spray outlet in the space to be treated and then resealing the metering container in readiness for the next treatment.

6. A method according to claim 5 wherein the sealing and unsealing of the containers is effected by way of a single valve.

7. A method according to either claim 5 or claim 6 wherein the sealing of the bulk container is effected in response to a predetermined weight of fluid being received in the metering container.

8. A method of spray of aerosol treating an interior space of a building substantially as described herein.

9. A method of supplying metered quantities of pressurised fluid to a chosen location from at least one container thereof in isolation from said location, comprising the steps of admitting a unit charge of said fluid to a metering vessel, said vessel being isolated from said location, isolating the container from said vessel, placing the vessel in communication with said location to supply said unit charge to said location, and then isolating the vessel from said location and repeating the sequence of steps.