EP1066215A1

EP1066215A1 - Blow-out preventing device for a spear valve

Info

Publication number: EP1066215A1
Application number: EP99911915A
Authority: EP
Inventors: Kenneth Leonard Simpson
Original assignee: Spears Ltd
Current assignee: Spears Ltd
Priority date: 1998-03-24
Filing date: 1999-03-22
Publication date: 2001-01-10
Anticipated expiration: 2019-03-22
Also published as: WO1999048801A1; DE69931153D1; EP1066215B1; DE69931153T2

Abstract

A keg has a spear fitted with a safety blow-out device (105, 106). Spring member (106) has three legs with outwardly turned ends (106d, 106e, 106f) that slot into equi-angularly spaced holes. The leg ends prevent the spear (101) from being extracted through the keg neck (102) since the diametrical extent of the legs is greater than the internal diameter of the neck. Appropriate relative axial movement of body (7) relative to tube (2) retracts leg ends (106d, 106e, 106f) within said neck internal diameter allowing extraction of the spear.

Description

BLOW-OUT PREVENTING DEVICE FOR A SPEAR VALVE

Description of Invention

This invention relates to kegs, containers or the like which are normally used in the pressurised dispensation of beer or other liquids.

Conventionally, a keg has a neck or a tubular extension, usually on one end face of a generally cylindrical keg body, and a spear which is assembled into the neck or tubular extension. The neck/extension may have a female screw-thread and the spear may have a complementary mating male thread or alternatively the spear may be held instead in the neck/extension by a circlip. The spear will usually include a tube which extends inside the keg, in use, generally from the neck/extension to a location close to the opposite end of the keg.

When beer or other liquid is dispensed, two valves in the spear are opened, one to admit pressuring gas and the other to allow discharge of the liquid. When a keg is filled, it is usually inverted and the two valves are opened to different extents to allow liquid to be admitted through one of the valves and gas to be discharged through the other of the two valves.

A well known problem with such conventional arrangements is that if any attempt is made to remove the spear whilst the keg is pressurised, the spear may be blown out and become in effect a potentially dangerous missile. Disadvantageously, many incidents have occurred where people have been injured in such circumstances. 2 Reference is made to the Applicant's patent specification No.PCT/GB98/02331 which describes an arrangement for a well-type spear which is purpose made for a neckless keg and which has a safety blow out device preventing pressurised ejection of the spear as a dangerous missile as aforesaid. However, whilst the Applicant believes that the arrangement as described in the aforementioned patent application No.PCT/GB98/02331 is a most advantageous arrangement where a keg/container is being fitted with a spear for the first time, the Applicant has recognised that a problem still exists with existing kegs or the like which have already been fitted with a spear without a safety arrangement, said spears more particularly being known as a "well-type" spear in the art.

It is important to realise that in the art relating to kegs or pressurised containers or the like for dispensation of liquids, spear types generally fall into two categories namely the "well-type" and "flat-top type" of spear. The problems involved with the safe fitting of such different spear types are dissimilar owing to the different nature of said spears. Well- type spears are provided with a well or opening in the top into which an extractor tool can be located in order to remove the spear for replacement and/or maintenance. Flat top type spears are spears which do effectively present a flat-top rather than an opening or well on the exterior of the keg, an example of same being shown in patent specification No.EP0025682. It is to be noted that well-type spears will generally employ two independently operable valves whereas the flat-top type spears employ a dependent two valve or double valve arrangement. Thus, well-type spears have two helical coil springs (one for each independently operable valve) whereas flat-top type spears usually employ one helical coil spring only.

As previously mentioned, spears (the name for the valve arrangement used for extracting the pressurised liquid out of a keg or other container) may still be in use which have no safety device for preventing the spear from blowing out on removal or tampering of the spear and other arrangements have indeed been 3 proposed for adapting or modifying the existing spear with a blow-out safety device, the spear then being replaced in the keg or container. Alternatively, the existing spear may be replaced by a completely new spear equipped with a blowout safety device. Usually, and somewhat disadvantageously, when the existing spear is modified with a safety device invariably it has to be almost completely rebuilt with replacement parts including the blowout safety device and such modification may be more costly than need be the case and may possibly require a greater amount of dexterity in assembly than need be the case. Once again, it is important that the blow-out safety device should be effective in practice.

The general form of well-type spears is well known and as previously stated the spear has two independent valves which, although independent, are usually activated together more particularly by a special tool which releases the pressure out of the keg and at the same time deactivates the blow-out safety device allowing removal of the spear where required whilst preventing the spear from flying out. The two independently operable valves are kept closed by their respective springs when not in use (i.e. closed) and the internal working parts of the valves are held together by a body and a retaining washer. The body of the spear is usually assembled into the keg by a screw thread co-operating with an internal thread on the neck (usually welded into the top end wall of the keg), the body being sealed to the neck by means of an 0-ring seal. During removal of the spear it is important that the pressure is released in the keg or otherwise the spear will fly out as a potentially dangerous missile. In kegs that are not fitted with a safety blow-out device it is possible that the spear could be unscrewed without the pressure being released so that the spear will fly out. In arrangements including a safety blow-out device it is not possible for the spear to fly out if the spear is unscrewed without pressure being released in the keg.

As previously mentioned whilst the problem of providing existing spears with safety blow-out devices has been recognised such devices tend to be 4 disadvantageous in certain respects. More particularly, one such arrangement proposes replacing the existing body of the spear previously referred to with a modified body so that the existing body is discarded. Such an arrangement tends to be disadvantageous at least from a cost point of view and may be disadvantageous in other respects. Specification No.EP0734999 is referred to which shows such a modified body and blow out device; this arrangement also appears disadvantageous in that a second tool is required in addition to the usual spear extraction tool.

It is an object of the present invention to at least alleviate one or more of the aforementioned, or other, disadvantages associated with spears and/or to provided an improved safety blow-out arrangement for an existing spear not possessing such a safety arrangement, more particularly for a well-type spear.

According to one aspect of the present invention there is provided a safety blow-out device for attachment to a spear, said device comprising a retaining washer co-operable with a spring member in such a manner that the radial extent of the spring member, in use, prevents blow-out of the spear in the event that removal of the spear from a keg or container is attempted without pressure being released from the keg or container, the arrangement being such that the radial extent of the spring member can be reduced allowing it to pass through a neck of the keg/container on axial movement of an inner tube of the spear relative to a surrounding body of the spear, said axial movement being provided, in use, by means of a tool.

Preferably, the spring member comprises an end portion which is usually circular having an aperture through which said inner tube of the spear is passed in use. The spring member may have a plurality of legs extending from the end portion, generally upwardly or towards the neck of the keg in use, said plurality of legs locating in holes or slots in the retaining washer. Preferably, the ends of the 5 legs are turned radially outwardly, preferably to extend approximately at right angles to the remainder of the associated leg. Thus, in use, in a locking position the ends of the legs may be arranged to lie generally in a transverse plane of the spear, when in a locking position. Preferably, at least two or three legs are provided with are equi-angularly spaced around the end of the spring member and (although 6 or more could be provided), preferably, said legs flare slightly outwardly in a conical fashion when the spring member is not under stress and, preferably, said legs curve smoothly into the flared-out ends.

Thus, preferably, the spring member is stressed when the leg ends are introduced into the holes/slots in the retaining washer.

Most preferably, in the in use position of the safety blow-out device on the spear an axial gap is provided between the said end portion of the spring member and a stop on said inner tube such that initial axial movement of the spear inner tube inwardly relative to the keg neck, in use, will be lost up until engagement of said end portion with said stop on the inner tube; at which point the end portion will move with said inner tube relative to the retaining washer and the outwardly-turned leg ends will begin to pull through the slots (along the curved portions provided which act as cammed surface) thereby gradually deforming the legs in an accurately controlled manner until they are pulled radially within the inner diameter of the neck of the keg, thus allowing the spear to be extracted through said neck (release position). In the fully retracted position, the curved parts of the legs may contact the inner tube, where said curved parts are provided and, in any event, the spring member legs will, preferably, remain engaged in the slots in the retaining washer, in which position the ends of the legs may extend at an angle of about 30+ 5° degrees to a transverse plane of the inner tube.

In practice, once the inner tube is returned to its previous axial position relative to the body of the spear, the spring member is such that it will be returned 6 to its previous position so that no permanent distortion will take place of the spring member as it is moved between its respective locking position and release position.

Further according to the invention there is provided a spear fitted with the safety blow-out device in accordance with the previous statement of invention.

Further according to the present invention there is provided a keg/container provided with at least one spear in accordance with the immediately preceding paragraph.

Further according to the present invention there is provided a method of adapting an existing spear not fitted with a safety blow-out device, said method comprising:-

a) Removing the spear from a keg or container;

b) Removing an existing retaining washer from a body of the spear and replacing same with a retaining washer fitted with a spring member (extending inwardly of the body in use into the keg or container) and replacing the spear in the keg or container, the arrangement then being such that the radial extent of the spring member can be reduced allowing it to pass through a neck of the keg or container on axial movement of an inner tube of the spear relative to a surrounding body of the spear, said axial movement being provided in use, by means of tool.

Further according to the present invention there is provided a spear having any feature or combination of features derivable from this description and/or drawings.

Further according to the present invention there is provided a spear fitted with a safety blow-out device, the safety blow-out device comprising one or more of the following features:- 7 a) a spring member mounted for limited free movement along an inner tube of the spear on relative movement of the body of the spear and inner tube, prior to contact of the spring member with a stop on the inner tube;

b) said limited movement in a) taking place, preferably, prior to distortion of the spring member on further relative axial movement of the body and inner tube, in order to reduce the radial extent of the spring member to a dimension within the internal diameter of a neck of a keg or container to which the spear is fitted;

c) a spring member with a plurality (preferably 3) of axially extending (preferably flared outwardly) legs having, preferably, integral outwardly turned ends joined, preferably, by smoothly curved portions, which curved portions, preferably act as cam surfaces in slots in a retaining washer attached to said body of the spear;

d) a spring member with a plurality of legs having outwardly turned ends engaged in slots in a retaining washer, said legs, preferably, extending inwardly beyond the bottom of a body of the spear, in use, preferably beyond a stop position on an inner tube of a spear, said stop position, preferably, being formed by an end of a wider diameter portion of said tube (said end preferably being part conical in shape);

e) an arrangement having a spring member with legs extending diametrically outwardly beyond the inner dimension of a neck of a keg or container, in a safety or locking position, said legs being pulled inwardly radially on appropriate axial movement of a body of the spear relative to an inner tube of the spear to within the inner diameter of said neck to allow extraction of the spear from the keg/container (release position), and

f) a lost motion device. 8

Further advantageous features will be evident from the following description and drawings.

An embodiment of a spear having a safety blow out device in accordance with the present invention will now be described, by way of example only, with reference to the accompanying illustrative drawings, in which :-

FIGURE 1 shows a part sectional view of a known "well-type" spear;

FIGURE 2 shows a front elevational view of a spear in accordance with the present invention, threadably engaged in a neck welded in on end wall of a keg (not shown) in partial cross-section in a normal, closed position;

FIGURE 3 shows a view similar to FIGURE 2 but with the spear in a position ready to be extracted from the keg;

FIGURE 4 shows views of a retainer washer of the spear shown in FIGURES 2 and 3; and

FIGURE 5 shows views of a spring member of the spear as shown in FIGURES 2 and 3, which spring member co-operates with the retainer washer shown in FIGURE 4.

FIGURE 1 shows a well known well-type spear 1 in half vertical longitudinal cross-section. Since the various components of the spear 1 are very well known, said spear is only briefly described here. The spear 1 has a long tube or stem 2 which, in use, extends down to near the inside bottom wall of the keg or other container or the like which, in use, contains liquid such as beer to be dispensed through the spear. The upper portion of the tube 2 tapers frustoconically outwardly at 2a to a wider diameter portion 2b (which should be evident from FIGURE 1 of the drawings) and said portion 2b houses a loosely coiled helical compression spring 3 having flattened end surfaces 3b, 3c supporting a valve member 4 9 constrained for longitudinal movement in the wider diameter tubular portion 2b, against the spring biasing force of spring 3 acting in a direction so as to return the valve member 4 to the top of the tube 2. The valve member 4 is located by a flanged seal 5 (of rubber or any suitable material) having a ribbed narrower diameter portion 5 a that fits snugly into the top of the tubular portion 2b more particularly as should be evident from FIGURE 1 of the drawings. Additionally, seal 5 is provided with an inner strengthening metal insert 6 of a shape which should be evident from FIGURE 1 of the drawings. Seal 5 seats an upper integral, radially outwardly extending lip or flange 2c of tube 2.

Thus, the spring 3 and valve member 4 comprises a first valve assembly, appropriate actuation of which allows beer (or other liquid) to flow outwardly from the keg through the neck of the keg (not shown in FIGURE 1 of the drawings). Thus, the valve assembly 3, 4 is effectively a poppet valve. An 0-ring seal of nitrile rubber or EPDM is provided at f to form a seal to prevent the contents of the keg/spear assembly from escaping.

The spear 1 includes a separate body 7 having an upper external screw thread which mates with the internal screw thread on a threaded neck of the keg (said neck being welded to an end wall of the keg) in a manner which is well known. The body 7 is introduced onto the tube 2 from above over the seal 5 and a second wider diameter loosely coiled helical coiled spring 8 having flattened end surfaces 8a and 8b is introduced onto the upper wider diameter portion 2b of tube 2 from the lower end of the tube 2 up inside the body 7. The helical coiled spring 8 is pushed right up inside the body 7 and retained thereto by means of a retainer washer 9 introduced onto the tube 2 from the lower end thereof.

The body 7 includes three, lower radially directed equi-angularly spaced lugs (not shown) which co-operate lockingly with three radial lugs (not shown) on the retainer washer 9. The gaps in-between the radial lugs on the body 7 allow 10 insertion of the lugs into the body on appropriate alignment of the retainer washer 9 with the body and then on appropriate relative rotation of the retainer washer 9 and the body the lugs on the washer 9 overlap the lugs on the body to lockingly retain the body 7 on the tube 2, with the helical spring 8 held captivate between the retainer washer 9 and the radially outwardly extending lip or flange 2c at the upper end of wider diameter tubular portion 2b.

It is to be noted that the rubber seal 5 is provided with a conical edge 5b which seats on an undercut, similarly angled conical edge 7c of the body 7. The seal acts as a second valve member that may be displaced longitudinally of the body with the tube 2 relative to the body 7 against the spring biasing force of the helical coil spring 8, in order to provide a second valve through which pressurising gas or fluid can be introduced into the keg or container in a well known manner; said pressurising gas or fluid being able to flow through the holes 7b in the body 7 into the liquid in the barrel.

A problem exists with the known well-type spear shown in FIGURE 1 in that it possesses no safety blow-out device. Thus, it is possible to rotate the spear 1 relative to the keg neck in order to unscrew said spear and, if the keg has not been de-pressurised by appropriate valve actuation, the spear will fly out since the radial extent of the washer 9 is less than the radial extent of the internal dimensions of the neck of the keg. If the radial dimensions of the retainer washer 9 were greater than internal radial dimensions of the neck there would be a radial overlap which would allow some outward displacement of the spear but which could prevent the spear from flying out of the keg possibly causing serious injury.

However, it is to be appreciated that if the retainer washer 9 were to be provided with a greater radial extent the spear could not be assembled and introduced into the neck of the keg from above and screwed therein because the retainer washer 9 would not fit into the neck owing to the prohibitive radial extent. 11 As previously mentioned, the Applicant is primarily concerned with modifying the type of well-type spear as shown in FIGURE 1 with a safety blowout device and accordingly FIGURE 2 shows a view of a spear 101 in accordance with an embodiment of the present invention. The spear 101 is shown screwed into a neck 102 welded to an end wall 103 of a keg by an external weld 104. The spear 101 includes exactly the same parts as shown in FIGURE 1 (which parts are numbered the same) except for the fact that the retaining washer 9 is now replaced by two components, namely washer 105 and co-operating spring member or bracket 106. FIGURE 3 is a view similar to FIGURE 2 with the washer 105 and spring member 106 shown in a second position with the radial extent of three legs 106a, 106b and 106c (see FIGURE 5) having been retracted to within the dimension x of the neck 102 of the keg in order to allow extraction of the spear 101 to take place through the neck 102 of the keg, when required.

Washer 105 is shown more clearly in FIGURE 4 of the drawings, and the format of washer 105 is generally similar to washer 9 save for the provision of three equi-angularly spaced holes or slots S which allow the introduction of the outwardly turned ends 106d, 106e, 106f of legs 106a, 106b, 106c to be passed therethrough in order to connect the spring member 106 to the retaining washer 105. As should be evident from FIGURE 5 of the drawings the spring member 106 has a central circular aperture 106g very slightly larger than the external diameter of the lower end of the tube 2, to allow the spring member to be slotted onto the tube 2 from the bottom thereof with the legs in an upward orientation as should be evident from FIGURES 2 and 3 of the drawings. The legs 106a, 106b, 106c flare out slightly as shown in FIGURE 2 with the ends 106d, 106e and 106f being arranged generally in a transverse plane of the spear.

On appropriate actuation of the rubber seal 5 in a downward direction (such appropriate actuation may be accomplished by using a special tool not shown), tube 2 is pushed downwardly relative to the body 7 against the spring force of 12 compression spring 8. This action closes the coils of the spring 8 together (see

FIGURE 3) with the flat circular end 106h of the spring member being brought into contact with the lower end of the conical portion 2a of the tube (which lower end acts as an axial stop for said flat end 106h) thereby pulling the legs 106a, 106b, 106c into the distorted shape as shown in FIGURE 3. The outwardly turned ends 106d, 106e, 106f of the legs are distorted and pulled inwardly, thereby reducing the radially outward extent of said legs 2 within dimension x, as required for extraction of the spear through the neck of the keg. It is to be appreciated that on removal of the tool from the neck of the body the resilient rubber seal 5 will seat on the appropriate tapered flange of the keg 7 returning the washer 105 and spring member 106 to their previous safety positions, more particularly as shown in FIGURE 2 of the drawings.

Axial gap X (see FIGURE 2) is regarded as being very important by the Applicant because the safety device is, thereby, not partly disengaged in a normal working situation of the spear. Thus, the gap X, advantageously, allows some relative axial movement of the body and tube 2 to take place without affecting the safety blow-out device in any way. Thus, the axial gap X provides, effectively a lost motion arrangement in disengaging the safety device.

It is to be understood that the scope of the present invention is not to be unduly limited by the particular choice of terminology and that a specific term may be replaced by any equivalent or generic teπn. For example the term "tube" could be replaced by "stem" or the term "member" could be replaced by "bracket". The terms "up and down" as used throughout the specification should not be interpreted as limiting and are used merely to indicate a general orientation e.g. during storage of the keg. Further it is to be understood that individual features, method or functions relating to the spear or safety blow-out device might be individually patentably inventive. In particular, any disclosure in this specification of a range for a variable or parameter shall be taken to include a disclosure of any selectable 13 or derivable sub-range within that range and shall be taken to include a disclosure of any value for the variable or parameter lying within or at an end of the range. The singular may include the plural or vice versa.

It is possible that the retaining washer 105 and spring member 106 arrangement in FIGURE 2 could be inverted so that the washer replaces the end 106g of the spring member and means (preferably integral means e.g. lugs) are provided on the spring member to engage with the lugs on said body 7.

Embodiments of the present invention may provide the spear 101 made up of the following: -

a) container top pressing and b) (102) neck - The liquid container/keg has a welded neck with an internal thread. The internal thread at 14 threads per inch is for the assembly of the spear into the liquid container/keg.

c) (7) Body Assembly - The body assembly holds the spear internal parts together. The body assembly is made up of two parts, the body casting and the skirt which is welded into the body casting. There is an external thread on the body casting which is for the assembly into the keg neck thread.

d) (8) Main Spring - The main spring closes the gas valve against the body and prevents any escape of gas or liquid out of the keg.

e) (2) Stem - The stem is a tube that goes to the bottom of the keg. In the dispense mode the liquid/beer in the keg flows up the stem from the bottom of the keg and out past the second valve. In the fill mode the keg is upside down and the stem has gases escaping out of the keg as the liquid/beer enters the keg.

f) O' Ring - The 'O' ring is made from nitrile rubber or EPDM and as the spear is tightened into the keg neck it foπns a seal. This prevents the contents of the keg/spear assembly from escaping. 14 g) (105) Retaining Washer - The new retaining washer fits into the skirt part of the body by three bayonet fittings. The internal parts of the spear are retained by this washer when it is assembled into the bayonet fitting in the body. This new retaining washer replaces the normal washer. The new washer is an investment casting and it has to be much stronger than the washer it replaces. The new retaining washer has three slots which permit the three prongs on the spring bracket to pass and slide through the slots easily. The retaining washer could, alternatively, be a machined part or pressing.

h) (106) Spring member/Bracket - This spring member/bracket is an additional part to a non safety spear to make it safe. The bracket has three prongs that pass through the three slots in the new retaining washer described earlier. When the spear is in the closed position or in the dispense mode the spring bracket has its three prongs projecting beyond the inside diameter of the keg neck. This prevents the spear from coming out of the keg and thereby making the device safe by stopping the spear from blowing out of the keg if the spear is unscrewed.

FIGURE 3 shows the spear 101 in the fully open position. This position is achieved by a special tool which compresses the main spring to a maximum and moves the stem some 11 to 11.5 millimetres.

The outline of the spear is made up of the following differences from FIGURE 1:-

i) Main Spring - The main spring is fully compressed and as can be seen the coils are forced together.

ii) Stem - The stem has moved some 11 to 11.5 millimetres from its closed position.

iii) Spring Bracket - When the spear is opened intentionally some 11 to 11.5 millimetres the stem comes into contact with the spring bracket. This action forces 15 the three prongs through the retaining washer slots to effect a reduced diameter of the prongs therefore permitting the spear to pass through the keg neck. The opening of the spear to perform this operation allows the keg to de-pressurise and renders it safe for extraction.

Referring to FIGURE 5, New Retaining Washer; the new retaining washer that has three slots with a width of 4.5 millimetres which are there to enable the new spring bracket prongs to pass through them freely. The new retaining washer is stronger than the washer it replaces as it has to withstand the impact load of the spear if it is unscrewed without releasing the keg pressure. A minimum gap between the inside diameter of the keg neck and the major diameter of the retaining washer needs to be achieved. This small gap will mean the spring bracket is unable to bend and pass through this small gap forcing the material of the three prongs into shear. The material is unable to shear as the forces are so great. Thus making the device have a high safety margin.

Referring to FIGURE 5, Spring Member/Bracket; key features are that the material has spring properties and at 1.0 millimetre thick it is both flexible to retain its shape in action and strong enough to act as a safety device to prevent the spear from coming out if blown out from a keg with a 5 bar pressure. The normal use of the spear in both its fill and dispense modes should not activate the effective reduction in the prong diameter. However, when the main spring is totally compressed the effective diameter is reduced to permit the spear to come out of the keg therefore the overall height at 27 millimetres is important to achieve these results, in the embodiment shown.

Some important and preferable aspects of the present invention are as follows:-

A. A safety arrangement for a double "well" type valve in particular for transportable containers of the type serving to distribute a liquid pressure from a 16 gas. The arrangement may comprise a spear which is the double "well" type valve mounted vertically in the neck of the container and able to be detached. The spear and the container may be screwed together and sealing is achieved by a rubber "O" ring. The spear may be made up of the Body Assembly which holds together the one gas valve held in place by the Main Spring, the second valve the poppet valve may be held in place by the Poppet Valve spring and a Stem tube which goes to the bottom of the container. The Retainer Washer may be locked into the Body Assembly holding the aforementioned parts in the Body Assembly and a Spring Bracket may be clipped into the Retainer Washer. The Spring Bracket may have three prongs which pass through three slots in the Retainer Washer.

B. A safety arrangement in which the spring bracket having the form of three prongs which pass through three slots in the retaining washer and beyond the diameter of the body skirt. This gives an effective diameter greater than the inside diameter of the keg neck.

C. A safety arrangement in that the three prongs act as springs and they are brought together by a ring which fits around the spear stem.

D. A safety arrangement in that the three prongs are of a form that means they are being pre-stressed when the spring bracket prongs are mounted in the slots in the retaining washer.

E. A safety arrangement characterised in that the three prongs in the pre- stressed position have a gap behind them and the spear stem.

F. A safety arrangement characterised in that when the spear is in its normal open position for dispensing liquid the larger diameter of the stem will not come into contact with the spring bracket ring that fits around the smaller stem diameter.

G. A safety arrangement characterised in that the three prongs on the spring bracket side freely through the three slots in the retaining washer. 17 H. A safety arrangement characterised in that when the spear is opened fully using a special tool until the main spring is completely compressed. Firstly the gases in the keg in this position escape from the keg rendering the assembly harmless by preventing the spear from flying out of the keg. Secondly the larger diameter on the stem comes into contact with the spring bracket ring which fits around the small diameter on the stem. This action pulls the three prongs through the slots in the retaining washer and reduces the effective diameter of the tip of the three prongs to a diameter less than the diameter in the keg neck permitting the spear to be removed through the keg neck.

I. A safety arrangement characterised in that all bacterial growth is washed and sterilised off the whole of the spear assembly including the spring bracket when the keg and spear are processed by a conventional cleaning and filling line.

Preferably, the gap should be at a minimum between the keg neck and external diameter of the new retaining washer. Shear force greater than bending force. Hence greater safety factor.

To summarise, the embodiments of the invention relate to:-

A retro-fit safety arrangement for a double valve "well" type spear made up of a spear that has no safety device to prevent the spear from blowing out under the force of the keg pressure, when it is unscrewed out of the keg without releasing the pressure in the keg. The safety device that is fitted retrospectively to such a spear is made up of an additional spring bracket (see FIGURE 4). Also the new retaining washer (see FIGURE 3) replaces the normally fitted pressed retained washer. The additional spring bracket together with the new retaining washer is assembled to the original spear (see FIGURE 1). The three prongs on the spring bracket have an effective diameter greater than the keg neck and prevent the spear from flying out of the keg under pressure when the spear is unscrewed from the keg. In order to remove the spear from the keg safely a special tool is used that opens the spear to 18 its maximum (see FIGURE 2). This action has two results: firstly the gases escape from the keg rendering the spear safe from blowing out and secondly the the prongs on the spring bracket are pulled through the three slots in the retaining washer by the downward movement of the stem. This second action results in reducing the effective diameter of the three prongs to be less than the keg neck and permits the spear to be removed from the keg once it has been unscrewed out of the keg neck.

The content of the priority document application No.9806131.0 is hereby incorporated into this application by reference.

Claims

19 CLAIMS :-

1. A safety blow-out device for attachment to a spear, said device comprising a retaining washer co-operable with a spring member in such a manner that the radial extent of the spring member, in use, prevents blow-out of the spear in the event that removal of the spear from a keg or container is attempted without pressure being released from the keg or container, the arrangement being such that the radial extent of the spring member can be reduced allowing it to pass through a neck of the keg/container on axial movement of an inner tube of the spear relative to a surrounding body of the spear, said axial movement being provided, in use, by means of a tool.

2. A safety blow-out device as claimed in claim 1 in which the spring member comprises an end portion having an aperture through which said inner tube of the spear is passed in use.

3. A safety blow-out device as claimed in claim 2 in which the end portion is circular.

4. A safety blow-out device as claimed in claim 2 or claim 3 in which the spring member has a plurality of legs extending from the end portion, generally upwardly or towards the neck of the keg in use, said plurality of legs locating in holes or slots in the retaining washer.

20 5. A safety blow-out device as claimed in claim 4 in which the ends of the legs are turned radially outwardly.

6. A safety blow-out device as claimed in claim 5 in which said ends extend approximately at right angles to the remainder of the associated leg and, in use, in a locking position, lie generally in a transverse plane of the spear.

7. A safety blow-out device as claimed in any one of claims 4 to 6 having at least two or three legs which are equi-angularly spaced around the end portion of the spring member.

8. A safety blow-out device as claimed in claim 7 in which said legs flare slightly outwardly in a conical fashion when the spring member is not under stress.

9. A safety blow-out device as claimed in claim 5 or any claim dependent therefrom in which said legs curve smoothly into the flared-out ends.

10. A safety blow-out device as claimed in any of the preceding claims in which the spring member is stressed when the leg ends are introduced into the holes/slots in the retaining washer.

11. A safety blow-out device as claimed in any one of the preceding claims in which in the in use position of the safety blow-out device on the spear an axial gap 21 is provided between the said end portion of the spring member and a stop on said inner tube.

12. A safety blow-out device as claimed in claim 11 in which on engagement of said end portion with said stop on further appropriate relative movement of the inner tube and body the outwardly-turned leg ends begin to pull through the slots thereby gradually deforming the legs in an accurately controlled manner until they are pulled radially within the inner diameter of the neck of the keg.

13. A safety blow-out device as claimed in claim 11 or 12 in which in the fully retracted position, curved parts of the legs contact the inner tube.

14. A safety blow-out device as claimed in claim 4 or any claim dependent therefrom in which the spring member legs remain engaged in the slots in the retaining washer in the fully retracted position.

15. A safety blow-out device as claimed in claim 14 in which the ends of the legs extend at an angle of about 30 + 5┬░ degrees to a transverse plane of the inner tube in the fully retracted position.

16. A safety blow-out device substantially as herein described with reference to FIGURES 4 and 5 of the accompanying drawings.

22 17. A spear including a safety blow-out device as claimed in any one of the preceding claims.

18. A spear substantially as herein described with reference to FIGURES 1 to 5 of the accompanying drawings.

19. A keg/container provided with at least one spear as claimed in claim 17 or claim 18.

20. A method of adapting an existing spear not fitted with a safety blow-out device, said method comprising:-

1) Removing the spear from a keg or container;

2) Removing an existing retaining washer from a body of the spear and replacing same with a retaining washer fitted with a spring member (extending inwardly of the body in use into the keg or container) and replacing the spear in the keg or container, the arrangement then being such that the radial extent of the spring member can be reduced allowing it to pass through a neck of the keg or container on axial movement of an inner tube of the spear relative to a surrounding body of the spear, said axial movement being provided in use, by means of tool.

21. A method of adapting an existing spear substantially as herein described. 23 22. A spear fitted with a safety blow-out device, the safety blow-out device comprising one or more of the following features:-

a) a spring member mounted for limited free movement along an inner tube of the spear on relative movement or body of the spear and inner tube, prior to contact of the spring member with a stop on the inner tube;

b) said limited movement in a) taking place prior to distortion of the spring member on further relative axial movement of the body and inner tube, in order to reduce the radial extent of the spring member to a dimension within the internal diameter of a neck of a keg or container to which the spear is fitted;

c) a spring member with a plurality (preferably 3) of axially extending (preferably flared outwardly) legs having, preferably, integral outwardly turned ends joined, preferably, by smoothly curved portions, which curved portions, preferably, act as cam surfaces in slots in a retaining washer attached to said body of the spear;

e) an arrangement having a spring member with legs extending diametrically outwardly beyond the inner dimension of a neck of a keg or container, in a safety or locking position, said legs being pulled inwardly radially on appropriate axial movement of a body of the spear relative to an inner tube of the spear to within the inner diameter of said neck to allow extraction of the spear from the keg/container (release position).