FIRE AND EXPLOSION SUPPRESSSION

FIELD OF THE INVENTION

This invention lies in the field of fire and explosion suppression, in particular the invention relates to mechanical equipment used in apparatus for fire and explosion protection. Apparatus of this kind has been described in South African patent 96/0178, granted to the present applicant, for example.

BACKGROUND

South African patent 96/0178 describes a valve for use in fire and explosion suppression apparatus, which valve is characterised by a piston in a cylinder, which is released by a sear when a squib is fired by opto-electronic devices, which detect the fire or explosion. The piston achieves very fast opening of the valve, for example, within 2 or 4 milliseconds, which is critical for dealing with explosions effectively. Extinguishing substance, for example held in a steel pressure vessel at 100 to 150 bar is released to nozzles or other distribution means when the valve opens.

The very fast opening of the valve, which achieves the critical advantage mentioned also poses a problem, for the valve piston may travel at mach 2 while opening. The problem is the necessary deceleration of the valve piston in the valve body once it has moved to the open position, the valve piston must be halted against some sort of buffer arrangement. To do this the considerable kinetic energy of the valve piston must be absorbed, otherwise the phenomenon arises that it bounces back from the buffer and tends to interfere with the necessary complete opening of the valve. The bouncing is caused partially by compression of air below the valve piston, acting as a pneumatic spring, to obviate this escape holes have been provided in the valve body below the buffer. The escape holes are effective to deal with the problem but introduce the disadvantage that extinguishing substance escapes through them when the valve opens and a loss of pressure is suffered. An initial aspect of this invention addresses this disadvantage.

The optoelectronic detectors of the apparatus are passive devices, which receive radiation from fire and/or explosion. The apparatus is typically used in very dusty and dirty environments, indeed flour, sawdust and similar finely dispersed combustible substances in air constitute the conditions that require fire and explosion protection, apart from the main application, which is in underground mining environments, particularly "fiery" mines, i.e. coal mines subject to the risk of methane presence. Underground mines are profoundly dirty environments. This requires cleaning of the detectors as accumulation of dirt renders them ineffective, a crucially important issue as lives depend on the operation of the apparatus, especially when explosions occur, let alone damage to equipment. A further aspect of this invention addresses this requirement.

The fire and explosion suppression apparatus has been applied to "roadway" protection in underground mining, in electrical substations, mounted on mining machines, especially coal mining machines where exposure of methane occlusions presents a serious risk and elsewhere. It has become apparent that a need exists for the application of the apparatus to be extended to have the qualities of versatility and of mobility, permitting the apparatus to be brought temporarily to locations where actions must be carried out in conditions, which pose a risk of fire and/or explosion. A mobile or portable apparatus must address the requirement of distribution of the extinguishing medium in differing surroundings in special ways. It has been found that where a "curtain" of extinguishing medium is sprayed out as a barrier to an advancing flame front, it is vital that the curtain is imperforate, even a small hole or gap in the curtain can allow the fire ball to pass through and on the other side expand with explosive force and destructive effect. A still further aspect of this invention addresses this requirement.

THE INVENTION

The present invention provides a valve assembly, which includes a body having a passage in the body, the passage adapted to provide communication

from a container of a substance under pressure to discharge means for the substance to ambient, a piston which can move in the passage as a valve from a sealing position to an opening position, a trigger mechanism which retains the piston in the sealing position by means of a sear that engages the piston and when triggered disengages the piston to release to piston to move to the opening position, a buffer means to receive the piston in the opening position, and in one aspect the buffer means including a housing enclosed from the ambient and including an inner return passage means, which communicates between the discharge means and the base of the buffer means.

The passage allows the air, which is driven by the piston to the base region of the buffer to escape to the discharge means and hence not cause a high pressure build up, which would be at risk of causing the piston to bounce back towards a closure position, thereby causing interruptions to the discharge.

The passage means preferably is provided by an inner shell located inside the buffer housing and presenting several passages from the buffer base region to the discharge means.

The discharge means may comprise vanes or pipes or nozzles, these chosen to direct the discharge in a suitable way, according to the application.

In another aspect of the invention there is provided a means of cleaning of opto-electronic detector glass (band pass filters), which comprises a body surrounding the glass (filters), a closure plate surrounding the glass, grooves in a surface of the body and/or closure plate, and passages communicating from a source of water or other cleaning fluid to the grooves. The grooves may be fashioned so as to eject the fluid onto the glass in a vortex and to leave the glass through an opening in the plate aligned with the glass. The opening also serves to admit radiation to the glass for detection of a fire and/or explosion optical signature. The term "glass" used herein includes any suitable transparent or translucent material.

In a preferred embodiment the body and/or the closure plate have further grooves, which are in communication with a supply of air or another gas under pressure, fashioned so as to direct an air jet or jets onto the glass so as to clean and/or dry it after a cleaning fluid has been ejected onto it. Again the air may be directed so as to adopt a vortex flow over the glass.

Another aspect of the invention provides a mobile or portable apparatus, which includes containers for fire and/or explosion suppression substance under pressure, valves for release of the substance, opto-electronic detectors, electronic means for relaying detection signals to valve actuation means and discharge means, which includes an array of nozzles, which are adjustable by means of provision for angular indexing and/or ball-and-socket alignment and/or substitution of alternative orifices or roses.

The indexing of nozzles may be made by use of a Vernier arrangement on circular scales of the nozzle and a body on which the nozzles is able to be rotated. The nozzle is given orifices, which produce jets of substance with a component of direction that is radial to the axis of rotation of the nozzle. Rotation accordingly provides a variation of the pattern of distribution of the substance. An array of indexed nozzles can be made to produce a sheet or "wall" of a spray of substance that can suppress a fire and/or advancing flame front of an explosion. The nozzles may be arranged in one or more concentric circular patterns, for example.

The ball-and-socket aligned nozzles can be used in addition or alternatively and directed as required, especially useful to direct substance towards locations that present a risk of lacking protection. Different roses may be used to obtain different spray effects, i.e. more or less dispersed, as required.

The mobile apparatus may be mounted on a wheeled chassis, for example with a hitch for towing by a tow vehicle. A back-up power source, such as a battery can be added. The mobile apparatus can alternatively have its own motive power.

THE DRAWINGS

The invention is more fully described by way of description with reference to the drawings, in which : -

Figure 1 is an axial section of a buffer means according to preferred embodiment of the invention,

Figure 1A shows a valve assembly,

Figure 1 B sows a valve body, valve piston and sear,

Figure 1C shows a piston valve caught in the catch of the buffer means,

Figure 2 is a plan view of the buffer means,

Figure 3 is an elevation on cleaning formations around detector glasses,

Figure 4 is an elevation on a cover plate to be bolted over the cleaning formations,

Figure 4A is an exploded view of an assembly holding the cleaning formations shown in figures 3 and 4,

Figure 5 is a side elevation of a portable apparatus according to a preferred embodiment of the invention,

Figure 6 is an end elevation of the apparatus,

Figure 7 is a plan view of the apparatus,

Figure 8 is an isometric view of the apparatus,

Figure 9 is an axial section of an indexable nozzle,

Figure 10 is an end view of the nozzle,

Figure 11 is an axial section of a part of the indexable nozzle,

Figure 12 is an end view of the part,

Figure 13 is an axial section of another part of the indexable nozzle,

Figure 14 is an end view of this part,

Figure 15 is an isometric view of the part of the indexable nozzle shown in figures 11 and 12,

Figure 16 is an isometric view of the part of the indexable nozzle shown in figures 13 and 14,

Figure 17 is an isometric view of the indexable nozzle,

Figure 18 is an isometric view of the indexable nozzle,, in "exploded" fashion,

Figure 19 is an axial section of a ball-and-socket aligned nozzle,

Figure 20 is an end view of the bal-and-socket aligned nozzle,

Figure 21 is an isometric view of the ball-and-socket aligned nozzle,

Figure 22 is an exploded view of this nozzle,

Figure 23 is a sectional view of an array of ball-and-socket aligned and indexable nozzles,

And

Figure 24 is an end view of the nozzles array.

THE PREFERRED EMBODIMENTS

In figures 1 and 2, there is shown the buffer means 1, which receives the piston when it has been driven into the opening position at very high speed by the pressure of the flame or explosion damping substance. The buffer means includes a housing 2, which is enclosed from the ambient and includes an inner return passage means, which communicates between the discharge means and the base of the buffer means. The passage means is formed, starting from the base 4 of the buffer, by holes 5 in the central piston guide 6, leading to a space 7 under the guide, then via indents 10 to a gap 8 between the housing and an outer guide 9. The air forced down by the descending piston escapes upwards to the discharge of the valve at the top of the gap 8. Located between the outer guide and the central guide are an elastic catch 11 for the piston and a surrounding bracelet 12. A description of the action of these two components can be found in the patent 96/0718, but the present invention provides the key advantage of preventing release of gas from the valve while also preventing build up of a back pressure that would cause bouncing of the valve.

Figure 1A and 1 B show a valve assembly 53, which includes a body 54 having a passage 55 in the body, the passage adapted to provide communication from a container 56 of a substance under pressure to discharge means 57 for the substance to ambient, a piston 52, which can move in the passage as a valve from a sealing position to an opening position, a trigger mechanism 58 which retains the piston in the sealing position by means of a sear 59 that engages the piston and when triggered disengages the piston to release to piston to move to the opening position,

Figure 1C shows a piston 52 caught in the catch 11 of the buffer means 1.

Figures 3 and 4 show a design for cleaning the detector lenses 13 and 14 used in a fire and explosion detector system. An aperture 15 is connected to a source of water at high pressure, that can be switched on to provide a strong flow of water. Communicating with the aperture are grooves 16 and 17 that lead to the lenses, a cover plate 18 is bolted over the grooves, so forming passages. The cover plate has holes 19 and 20 that allow radiation from fire or explosion to enter the detector lenses and also allows cleaning water to escape. The passages formed by the grooves enters the space at the lenses at tangential directions so as to cause a strong swirl or vortex, cleaning the lenses before escaping from the holes 19 and 20. A hole 21 is connected to a source of air under high pressure able to be switched on to cause a strong air flow into the grooves 22 and 23, again the cover 18 bolted over the grooves forms passages for the air, leading to the spaces for the lenses. The air passes over constrictions 24 and 25, which accelerate the air flow, causing a strong effect blowing the water off the lenses and drying the lenses. These flows of water and then air can be made to occur periodically to keep the lenses clean, despite very dirty conditions as can prevail in mines.

Figure 4A shows an "exploded view of an assembly holding the detector lenses shown in figures 3 and 4. This view shows the detector holes angle, which is 60 degrees in this example.

Figures 5 to 8 show a mobile apparatus 3 for extinguishing a fire or explosion, which includes containers 26 for fire and/or explosion suppression substance under pressure, valves 27 for release of the substance, opto-electronic detectors 28, electronic means 29 for relaying detection signals to valve actuation means and discharge means 30, which includes an array of nozzles 31, which are adjustable by means of provision for angular indexing and nozzles 32, which are adjustable by ball-and-socket alignment. The apparatus is mounted on a chassis 33 with wheels 34 and a tow hitch 35. A back-up battery power pack 36 is added.

Figures 9 to 18 show an indexable nozzle 37 used, for example, in the mobile apparatus shown in preceding figures. As shown in figures 9 and 10 the

indexing of nozzles is done by use of a Vernier arrangement on circular scales of the nozzle part 38 and a body 39 on which the nozzle is able to be rotated. The nozzle is given an orifice 40, which produces a jet of substance with a component of direction 41 that is radial to the axis 42 of rotation of the nozzle part. A cover cap 43 is shown, this is blown off when the substance is released and so keeps the nozzle clean until that event occurs (which can be after years of inactivity). Rotation accordingly provides a variation of the pattern of distribution of the substance. An array of indexed nozzles can be made to produce a sheet or "wall" of a spray of substance that can suppress a fire and/or advancing flame front of an explosion. This is shown in figures 5 to 8, for example. The nozzles may be arranged in one or more concentric circular patterns, for example.

Figures 11, 12 and 15 show the nozzle part separately, in which the indexing holes 44 are visible.

Figures 13, 14 and 16 show separately the body on which the nozzle part is rotated, in this view the holes 45 are shown, which correlate with the indexing holes in the nozzle part, to provide the Vernier effect, in which the nozzle may be rotated by increments of 5 degrees, around the full 360 degrees. There are eighteen holes in the body and four in the nozzle part, to give this effect.

Figure 17 shows the assembled indexable nozzle and figure 18 the same, with components "exploded".

Figures 19 to 22 show a ball-and-socket adjustable type nozzle 46, in which a ball 47 can be oriented in any direction within limits within a socket 48. A nozzle 49 has a "rose" 50 with many holes 51, which provide a distributed pattern of spray. A cap 52 is shown, which is blown off when the discharge of substance occurs.

Figures 23 and 24 show an array of indexable nozzles and ball-and-socket type nozzles mounted in an array that provides a curtail of extinguishing

substance. This array is used, for example, on the portable apparatus shown in preceding figures.

REFERENCE NUMERALS

1 buffer means

2 housing

3 mobile apparatus

4 base

5 holes

6 central piston guide

7 space

8 gap

9 outer guide

10 indents

11 catch

12 bracelet

13 lens

14 lens

15 aperture

16 groove

17 groove

18 cover plate

19 hole

20 hole 1 hole 2 groove 3 groove 4 constriction 5 constriction 6 containers 7 valves 8 detector 9 electronic means

discharge means nozzles array indexable nozzle ball-and-socket adjustable nozzle wheels tow hitch back up battery nozzle nozzle part body orifice radial direction axis cover cap indexing holes holes nozzle socket ball rose holes cap piston valve assembly valve body valve passage container of a substance discharge means trigger mechanism sear detector holes angle