GB2141182A - Space spraying system - Google Patents

Abstract

Apparatus for spraying agent 4 comprises a bulk storage tank (3) for the agent, a separate bulk storage vessel for propellant, means to transfer a unit treatment charge of agent into a pressure vessel (20) and timer controlled injector (34, 17) means to expel that charge from the pressure vessel (20), mix it with propellant and deliver the mixture to a plurality of spray nozzles (30). <IMAGE>

Description

SPECIFICATION Space spraying system This invention relates to space treatment systems of the kind used to treat building interiors with insecticides, pesticides, fungicides, deodorants and other such agents, in aerosol form. Such systems are also used in outdoor installations such as sewage farms for deodorising and in agricultural installations where insecticides, pesticides or the like may be dispersed.

Typically, systems of the kind under discussion comprise a bulk pressurised container of propellant and agent, a piping system extending from that container throughout the building, outlet sprays at various points along the piping and timer operated control valves for the control of flow of mixed propellant and agent from the container to the spray outlets.

In such systems the propellant serves not only to expel the agent but also at the point of expulsion to reduce the agent to the minute droplet form characteristic of an aerosol.

It will be appreciated that agents of the kind under discussion are usually relatively toxic in nature and therefore treatment is usually effected at night when the building is likely to be free of people. Nevertheless, malfunction of the timing equipment or of one or other of the control valves has occasionally led to untimely release of the aerosol into buildings.

Furthermore, in known systems if there is equipment failure the entire contents of the bulk container are likely to be released into the building in a single event, thus greatly augmenting the undesirable nature of the untimely release. Indeed, it is not too much to say that the sudden release of the entire contents of the bulk container into a crowded building such as a supermarket or shopping centre is a genuine disaster.

The likelihood of valve failure or the development of a leak in the piping system has been enhanced in recent times because of the increasing use of carbon dioxide as the propellant to avoid the undesirable environmental and health hazards presented by lower pressure hydrocarbon- propellants.

Hitherto, in attemps to reduce the likelihood of the entire contents of the bulk container being released, it has been proposed to substitute a smaller sized dosage container in the system which is periodically filled from the main container either manually or under the control of a separate timing system. That expedient is only partially successful in that it may limit the amount of agent inadvertently liberated but does not reduce the likelihood of plant failure occasioned by storing the agent under pressure. Furthermore, for practical considerations the pressurized bulk container has to be reasonably close to the building and may constitute an explosive hazard in the event of fire or other emergency conditions.

The present invention seeks to overcome or at least ameliorate the above-indicated disabilities in aerosol space treatment systems and does so primarily by ensuring that the agent is stored at atmospheric pressure and is induced into the flow of propellant in the piping system only during a treatment operation.

Furthermore, in preferred embodiments a dosage size container is incorporated between the bulk container and the system so that in the less likely event of an untoward release occurring it will be limited in magnitude as in prior known systems incorporating such a container.

The invention consists in a space treatment apparatus comprising a spray pipe system including outlet spray nozzles throughout the space to be treated, an unpressurised bulk container adapted to hold a bulk supply of treating agent, a pressure vessel adapted to hold a single treatment charge of treating agent, a pressurised source of propellant, supply means to introduce a single treatment charge of agent into said pressure vessel, injector means adapted when connected to said source to expel agent from said pressure vessel, to mix the expelled agent with propellant, and deliver the mixture into said pipe system, a delivery valve controlling propellant flow from said source to said injector means, and a timer mechanism controlling the sequential operation of said metering means and said delivery valve.

By way of example, an embodiment of the invention is described hereinafter with reference to the accompanying drawings.

Figure 1 is a schematic diagram of a space treating apparatus.

Figure 2 is diagrammatic sectional view of portion of an injector means appearing in Fig.

1, drawn to a larger scale.

The illustrated apparatus comprises a bulk container in the form of an outdoor tank 3 for holding a bulk supply of treating agent 4 the tank 3 may be provided with a pressure vent 5 which incorporates a chamber holding an absorbent medium and a drying medium to prevent ingress of moisture or the egress of agent vapour.

A pipeline 6 extends from the bottom of the tank 3 to one port of a two-way (on-off) valve 7. The other port of valve 7 is connected by a pipeline 8 to the bottom of an agent metering container 9 which may be-within the building to be treated.

An aspirator tube 10 extends slidably through a seal 11 in the top of metering container 9 to the upper interior of the tank 3 enabling a lower, rigid part of tube 10 to be raised or lowered to control the extent to which the tube 10 extends into the container 9 thereby to control the depth of agent in the container 9 at any time.

Aspirator tube 10 may be calibrated and/or the metering container 9 may be provided with a sight gauge to enable the quantity of agent in the container to be set as desired to provide a single treatment charge 1 2 of agent therein.

The second two-way (on-off) valve 1 3 is mechanically connected to valve 7. The two valves 7 and 1 3 are connected out-of-phase so that when one valve is "on" the other is "off". Valves 7 and 1 3 are operated by an actuator cylinder 14 which is normally biased to a position in which valve 7 is open thus placing the metering container 9 in communication with the tank 3.A pipeline 1 5 connects pipeline 8 with one port of valve 1 3 whilst the second port connects by pipeline 1 6 with a distributor block 1 7. By internal passageway 18 in block 1 7 communication is made with a pipeline 1 9 which extends into the base of a pressure vessel 20. Within vessel 20 there is a separator piston 21 which floats on top of any agent within the vessel 20.

As will be seen in Figure 2 an injector means comprises three passageways 22, 23 and 24 formed within distributor block 1 7. A port 25 introduces propellant into the passage 22 and (by internal passage 26) also into the top of vessel 20. Port 27 into which passage 18 enters receives agent from the pressure vessel 20 by way of pipeline 19.

By way of the internal passages 22, 23 and 24, agent and propellant flowing in through ports 27 and 25 are combined and mixed agent/propeliant emerges from port 28 into a spray pipe system 29 including spray nozzles 30. A propellant supply line 35 upstream of the injector has a branch line 31 which connects with actuator 1 8.

Located in pipeline 31 is a pressure regulating valve 32 which reduces the high pressure of the propellant to a desired lower working pressure, and a solenoid operated three-way supply-exhaust valve 33 which is electrically connected to a timer 34. The three ports of valve 33 are an inlet for propellant from regulator 32, an outlet to actuator 14 and an exhaust from actuator 14. Propellant supply line 35 downstream of its connection with line 31 but upstream of port 25 is provided with a two-way (on-off) solenoid valve 36. Valve 36 is electrically connected with timer 34 and controls the supply of propellant to the injector within distributor block 1 7.

As described above generally tank 3 is in communication with metering container 9 as valve 7 is in the open position. Metering container 9 receives and holds the desired amount of agent to be dispensed by the propellant. When it is desired to mix agent/propellant the timer 34 operates to open solenoid valve 33 thereby supplying propellant at reduced pressure to actuator 14. Actuator 14 operates both two-way valves 7 and 1 3 turning valve 7 "off" or closed to flow of agent and valve 1 3 "on" allowing agent to flow by gravity from container 9 to the pressure vessel 20 raising the floating piston 21.

At a set time lapse from the actuation of solenoid valve 33 timer 34 de-energizes valve 33 which then opens the line connecting it with actuator 14 to atmosphere. Spring loading within actuator 14 reasserts itself to operate valves 7 and 1 3 so that once again tank 3 is connected with container 9 and valve 1 3 is closed.

Timer 34 next energizes solenoid valve 36 permitting high pressure propellant to flow from its source, not shown, along pipeline 35 entering the injector at port 25 where the pressure of flow is felt in two directions. One direction is through the injector to port 28 and thence to spray nozzle 30. By internal passage 26 propellant is also directed into the top of pressure vessel 20 above the floating piston 21 forcing it downward to dispel the agent from the lower portion of vessel 20 through pipeline 1 9 to inlet port 27 of the injector, the agent then being drawn into the propellant and supplied at a desired strength of agent/propellant moisture to spray nozzles 30.

After allowing sufficient time to dispel the total amount of agent, timer 34 de-energizes solenoid valve 36 stopping the flow of propellant. The system remains static until it is next desired to repeat the operation detailed above, this being arranged by suitable setting of timer 34.

As the space above the floating piston 21 in pressure vessel 20 is in direct contact with spray nozzles 30 the pressure above the piston is dissipated to atmosphere once the supply of propellant is ceased by closure of valve 36. Any agent within line 16 and passage 18 is drawn into the flow of propellant through the injector so that when the dispensing operation is complete no agent remains on the downstream side of valve 1 3.

In other embodiments of the invention the isolating valves 7 and 1 3 may be replaced by a 3-port 2-way valve. Furthermore, but less preferably that valve may be directly controlled or operated by the timer. The advantage of using propellant pressure to operate valves 7 and 1 3 is that there is no attempted operation in the absence of propellant.

In simpler, less preferred, systems the pressure vessel may be sized to hold no more than a single treatment charge and may be filled directly from the bulk container at the start of each treatment operation.

According to another embodiment of the invention the injector means may be duplicated and the timer may be arranged to control the sequential operation of the respective injector means to enable one means to be in operation while the other is being refilled or standing by. In this way a continuous or substantially continuous supply of propellant and agent may be delivered to the piping system for use in instances where continuous treatment of the space concerned is called for.

Claims (5)

1. Space treatment apparatus comprising a spray pipe system including outlet spray nozzles throughout the space to be treated, an unpressurised bulk container adapted to hold a bulk supply of treating agent, a pressure vessel adapted to hold a single treatment charge of treating agent, a pressurised source of propellant, supply means to introduce a single treatment charge of agent into said pressure vessel, injector means adapted when connected to said source to expel agent from said pressure vessel, to mix the expelled agent with propellant, and deliver the mixture into said pipe system, a delivery valve controlling propellant flow from said source to said injector means, and a timer mechanism controlling the sequential operation of said metering means and said delivery valve.

2. Apparatus according to claim 1 wherein said supply means comprise an unpressurised metering container adapted to receive the single treatment charge of agent, and isolating valve means under the control of the timer and admitting of two mutually exclusive conditions, namely a first condition wherein the bulk container is in communication with the metering container for the delivery of a single treatment charge of agent thereto and a second condition wherein the metering container is in communication with the pressure vessel for the delivery of the charge thereto.

3. Apparatus according to claim 2 wherein said isolating valve means comprise two mechanically linked on-off valves, a propellant pressure operated actuator for said on-off valves, and a three-way supply-exhaust valve under the control of said timer for the admission of propellant to and venting of propellant from said actuator.

4. Apparatus according to claim 2 or claim 3 wherein said pressure vessel is divided into upper and lower chambers by a float adapted to rise and fall with the level of agent in the vessel.

5. Space treatment apparatus substantially as described herein with reference to the accompanying drawings.