GB2088208A - Pressure container discharge head - Google Patents

Abstract

Discharge head for providing a facility for automatic discharge of pressurised aerosol-type containers, particularly automatically actuated fire extinguishers for example stored pressure dry powder of "Halon" extinguishers. The head is mounted on the container neck after the container has been charged and tested and incorporates a hollow actuating stem which is inserted through a body of the head to engage and retain in an open position the spring loaded valve of the container itself. A displaceable closure element, for example a heat- responsive frangible bulb, engages the stem and seals its discharge passage. Retaining means, for example wedge like elements which engage a step in the body bore, hold the valve open once the stem has been inserted so that when the closure element is displaced discharge occurs through the stem passage. <IMAGE>

Description

SPECIFICATION Pressure container discharge head This invention relates to discharge heads providing a facility for automatic discharge from pressure containers; particularly but not exclusively for incorporation in automatic fire extinguishers.

Use of pressure containers, usually of seamed tinplate or impact extended aluminium, which are filled with a charge of fluid or powder substances including and/or together with a propellent is well known, particularly for liquids to be discharged as an aerosol spray and for fire extinguishers, usually of the smaller portable type, of the stored pressure dry powder or "Halon" types. A standard pattern of closure and discharge valve has been evolved for this kind of container in the form of a dished closure plate whose rim fits over the neck opening of the container body, and is retained in position by means of internal crimping under the inside of the body neck opening.A self-sealing valve assembly is located axially of the container at the centre of said plate and incorporates a spring loaded valve plunger which can be opened inwardly against the internal pressure by insertion of an actuating stem, for example a hollow aerosol push button spray head or other stem acting as a discharge duct. Containers of this type provided with this pattern of closure and valve assembly are hereinafter referred to as "aerosol-type pressure containers".

Our co-pending patent application 8005422 (20501 59A) dated 18th February 1980 describes a discharge head which can be particularly conveniently mounted on the closure rim of an aerosol-type pressure container to provide selective (i.e. non-automatic) discharge of a stored pressure dry powder fire extinguisher by means of a lever or trigger which can be operated to depress a hollow actuating stem acting on the plunger of the valve assembly.

The object of the present invention is to provide a neat, economic, and reliable automatic discharge head for this type of container which facilitates manufacture and assembly and which gives a compact self-contained unit which can be employed in a variety of installations.

According to the invention there is provided an automatic discharge head for an aerosol-type pressure container as hereinbefore defined, said head including a body, means for securing the body onto the container with the latter in a filled and pressurised condition, a through opening in the body being aligned with the valve assembly of the container when the head is so secured, an actuating stem received in said opening and defining a discharge passage, a dispiaceable closure element positioned in the body to urge the stem to an inner position at which it displaces the valve plunger of the container valve assembly to an open position, said closure element also sealing the discharge passage, and retaining means holding said stem at said inner position so that discharge takes place therethrough as soon as the closure element is displaced.

In the case of a fire extinguisher said closure element may be a frangible bulb or other form of heat-responsive element, said displacement occurring when the element is deformed or destroyed due to a rise in ambient temperature above a pre-determined level and/or by operation of an actuator mounted on the head and controlled automatically or otherwise from a remote station.

The head may further include a monitoring device providing a signal to a remote location and or actuating an alarm or other warning device if and when discharge takes place, for example responsive to said displacement of the closure element.

One practical embodiment of the invention is now more particularly described with reference to the accompanying drawings wherein: Figure 1 is a longitudinal section of an automatic discharge head assembled onto a pressure container.

Figure 2 is a side elevation of said assembly, and Figure 3 is an enlarged longitudinal sectional view of part of said assembly.

The assembly shown is a small automatic fire extinguishes, particularly for use in a high fire risk enclosure such as beneath the bonnet or in the engine compartment of a motor vehicle or boat.

The assembly comprises a charged pressure container of the aerosol-type which, in itself, is of conventional construction comprising a metal bottle 6 having a dished metal closure 7 crimped onto its neck opening, said closure locating centrally a self-sealing valve assembly 9. The container is filled, closed, and tested before the discharge head hereinafter described is mounted thereon.

An automatic discharge head comprises a body 1 2 of high strength plastics material having a generally cylindrical proximal end portion 20, a pair of parallel intermediate limbs 21 and a smaller diameter distal end portion 22.

The end face of proximal portion 20 is recessed to receive a plastics clamp ring 5 which will seat on the rim of closure 7 with a flexible skirt portion projecting therein. A screw wedge 4 has a tapered head portion which will spread the skirt of ring 5 when screwed into a threaded part of the through bore in proximal portion 20, the diameter of said head permitting it to be entered into the mouth of closure 7 with the skirt in an undeformed condition.

This method of securing a head on a pressure container is described in our said co-pending patent application 8005422 (20501 59A) but it will be appreciated that the present invention can be applied to heads which are mounted on a pressure container in other ways.

A seal ring 1 3 is positioned in a recess of wedge 4 before mounting the head on the container, said mounting is effected by clamping the head onto the container by rotating screw wedge 4 with a tool inserted through said central bore and engaging a hexagon or like central aperture of wedge 4.

A headed hollow actuating stem 11 which acts as a valve plunger is next inserted through the body into the aperture in proximal portion 20. Said aperture has a restricted diameter adjacent limbs 21 and stem 11 is dimensioned so that its head will seat against the axiaily outer face of said portion and will be retained by the engagement of wedge-shaped barbs 23 immediately below said restricted diameter which will resist subsequent withdrawal of the stem.

Said stem extends through portion 20 and screw wedge 4 to project into valve assembly 9 when the assembly is completed. A step on stem 11 compresses seal ring 13 into fluid tight engagement with the top of the valve assembly and, at the same time, the end of the hollow stem depresses the valve plunger to form a connection with the container interior.

A seating is formed at the outer end of stem 11 to receive an 0 ring seal 14 against which abuts the end of a standard temperature responsive frangible bulb 28.

Buib 18 is retained in place by a screw bulb holder 10 threaded into distal end portion 22.

In this way the assembly is fluid sealed with the plunger of valve assembly 9 held open. When bulb 1 8 is shattered, e.g. by a rising ambient temperature byeond the predetermined response level, the outer end of stem 11 is opened so that there is through passage for immediate discharge of extinguishant from the container.

Various ancillary control and monitoring devices may be provided in or on the head according to requirements, for example a microswitch 16 may be mounted in one limb 21 so that a spring loaded plunger thereof bears on one side of bulb 18. When the bulb collapses the plunger will be released for closing or opening an electrical circuit which may be used to actuate an alarm system and/or initiate operation of other extinguishing or emergency apparatus.

A plunger-type actuator 1 5 may be mounted in the other limb 21 connected electrically or otherwise for operation under remote control, e.g.

automatically in response to the actuation of a similar extinguisher in another location or a smoke or fire detector; and/or manually by response to an alarm press button or other selectively operated control at a remote location. Actuator 1 5 includes a striker pin which will shatter bulb 1 8 and initiate discharge of the extinguisher when operated.

The invention provides a particularly effective, compact, and economical extinguisher construction giving ease of assembly and use of corrosion resistant plastics components, with the added advantage of their low coefficient of heat giving quick response due to absence of the "heat sink" effect. Containers can be filled, pressurised and tested using standard procedures and equipment before the discharge heads are mounted thereon minimising wastage of components if any have to be rejected, and facilitating the testing procedures.

Claims (12)

1. An automatic discharge head for an aerosoltype pressure container as hereinbefore defined, said head including a body, means for securing the body onto the container with the latter in a filled and pressurised condition, a through opening in the body being aligned with the valve assembly of the container when the head is so secured, an actuating stem received in said opening and defining a discharge passage, a displaceable closure element positioned in the body to urge the stem to an inner position at which it displaces the valve plunger of the container valve assembly to an open position, said closure element also sealing the discharge passage, and retaining means holding said stem at said inner position so that discharge takes place therethrough as soon as the closure element is displaced.

2. A head as in Claim 1 wherein said actuating stem is inserted into the through opening after the body has been secured into the container.

3. A head as in Claim 1 or 2 wherein the retaining means includes interengaging formations on the body and stem shaped to permit the stem to be pressed into the inner position on assembly but to resist subsequent withdrawal.

4. A head as in Claim 3 wherein said formations include wedge-shaped barbs which engage a reduced diameter portion of the body through opening.

5. A head as in any preceding claim wherein the closure element is a heat-responsive element which will be deformed or destroyed by a rise in ambient temperature above a pre-determined level to permit discharge through said passage.

6. A head as in Claim 5 wherein the heatresponsive element is a frangible bulb.

7. A head as in any preceding claim including an actuator selectively operable from a remote station to effect displacement of the closure element.

8. A head as in any preceding claim including a monitoring device responsive to displacement of the closure element or some other condition arising from discharge to provide a signal indicating the occurrence of discharge.

9. A discharge head substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

10. The combination of a discharge head as in any preceding claim and an aerosol-type pressure container as hereinbefore defined.

1 The combination of Claim 10 in the form of a fire extinguisher.

12. A fire extinguisher substantially as hereinbefore described with reference to and as shown in the accompanying drawings.