CA2069841A1 - Portable foam dispenser - Google Patents

Abstract

A B S T R A C T

A portable apparatus 10 for supplying and dispensing a settable foam mixture includes a propellant container 12, a propellant 14 at a suitably high pressure contained within the propellant container 12, an unpressurised resin container 16, resin 18 contained in the resin container 16, an unpressurised catalyst container 20, catalyst 22 contained in the catalyst container 20, a spray gun 26, a connecting means for connecting the propellant container 12 to the spray gun 26, the resin container 16 and the catalyst container 20, connecting hoses connecting the resin container 16 and the catalyst container 20 to the spray gun 26 and a valve means 24 between the propellant container 12 and the connecting means for supplying, in use, propellant 14 to the resin and catalyst containers 16, 20 and the spray gun 26 at a reduced pressure. The invention also extends to a spray gun.

Description

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A POR~LE ~ DISPENSER

THIS INVEN~ION relates to a portable foam dispenser. More particularly, it relates to an apparatus ~or mixing liquid catalyst and resin which have fast reaction times and congestive properties and - for spraying the resultant mixture, and to a spray gun.
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According to a first aspect of the invention there is provided an apparatus for supplying and dispensing a settable foam mixture, which includes a high pressure propellant container which is a metal bottle which, in use, contains a gas propellant;
a pair of low pressure plastic bottles one of which, in use, contains resin and the other, in use, contains catalyst;
a spray gun for mixing the resin and catalyst and for spraying the resulting mixture;
connecting hoses for connecting the metal bottle to each of the plastic containers and for connecting the metal bottle and both plastic containers to the spray gun; and a valve means for controlling the flow of propellant from the metal bottle to the plastic bottles and from the metal bottle to the spray gun, and the flow of resin and catalyst through the spray gun.

206~g~1 Further according to this aspect of the invention there is provided an apparatus as described above, in which the metal bottle contains a gas propellant which is at a relatively high pressure and one plastic bottle contains resin and the other catalyst and both plastic bottles are unpressurised.

The metal bottle may be at a supply pressure of about 5 MPa.

~Further according to the invention there is provided a portable apparatus for supplyinq and dispensing a settable foam mixture which includes a propellant container;
a propellant at a suitably high pressure contained within the propellant container;
an unpressurised resin containeri resin contained in the resin container;
an unpressurised catalyst containeri catalyst contained in the catalyst container;
a spray gun;
a connecting means for connecting the propellant container to the spray gun, the resin container and the catalyst container;
connecting hoses connecting the resin and catalyst container to the spray gun; and a valve means between the propellant container and the connecting means for supplying, in use, propellant .

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to the resin and catalyst containers and the spray gun at a reduced pressure.

The valve means may include a distribution valve for controlling the supply of propellant, in use, to the resin container, the,catalyst container and the spray gun. The propellant container may be at a supply pressure of about 5 MPa and the distribution valve may be such that it supplies propellant to the resin container , the catalyst container and the spray gun at a distribution pressure, in use, which is much lower than the supply pressure. Thus, the distribution pressure may be in the region of 300 KPa.

The distribution valve may have a first orifice which restricts the flow of gas from the propellant container to provide the required drop in pressure.
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It will be appreciated that the distribution valve will have three outlets, one of which is connected to the spray gun, and the other two being connected to the resin container and the catalyst container respectively, by means of the connecting hoses.

It is further to be appreciated that the spray - gun will operate at a pressure, known as the application - pressure, as a result of the pressure of the propellant . , 2 ~

utilised by it. Thus, the apparatus may include an application pressure controL means for controlling the application pressure of propellant utilised within the sE)ray gun.

The application pressure control means may include a first orifice and a second orifice. The first orifice may be located at the propellant container and the second orifice may be spaced therefrom and may be between the propellant container and the interior of the spray gun. In the foam dispenser application the second orifice may be located between the spray gun and the distribution valve. Preferably, the second orifice is located at the spray gun end of a hose connecting the propellant container to the spray gun, or in a component of the spray gun.

Those skilled in the art will appreciate that the application pressure will be determined by the balance of the mass flow rate through the first orifice and that of the second orifice. Since both orifices restrict the flow of the gas prop~llant, flow is choked by both restrictions and the mass flow rate through each is provided by the following equations:-Mass flow rate =constant x area x upstream stagnation pressure - . upstream stagnation sonic velocity.

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It will be appreciated that the gas propellant is used to displace resin and catalyst from the bottles to deliver the resin and catalyst to the spray gun.
I'hus, the mass flow rate through the second orifice is equal to the mass flow rate through the first orifice minus the rate of flow of displacing gas which is required to displace the resin and catalyst from their bottles. The rate of flow of displacing gas is determined by the rate at which the reactants are consumed, which in turn is a function of the application pressure.

As the relationship between the application pressure and supply pressure is strongly related to the relationship between the areas of the orifices, the ratio of the areas of the orifices may approximate the desired ratio of supply pressure to application pressure.

Further according to the invention, the distribution valve may be non-reversible. Thus, once the valve is operated to permit flow of propellant out of the propellant container, it is not possible to operate the valve to stop the flow of propellant from the propellant container. Thus, in one embodiment, the distribution valve may have a disc that is ruptured, to permit flow of gas from the propellant container. A

piercing member may then be provided to pierce the disc 2 ~

when the apparatus is to be used. As a safety feature, t:he disc may also be such that, if the pressure in the propellant container exceeds a predetermined value, it ruptures. Preferably, the first orifice is located between the disc and the interior of the propellant container, so that gas is released from the propellant container in a controlled manner.

The distribution valve may further be such that there is an unimpeded flow path from the disc to a nipple whereby the valve is connected to the hose that connects it to the spray gun. Further, the spray gun may be such that there is no further valve means for controlling the flow of gas from the distribution valve and through the spray gun into the atmosphere. Thus, a safety vent flow path is provided between the rupture disc and atmosphere, that is always open, via the spray gun, in the event that the disc should rupture because the pressure in the propellant container exceeds the predetermined safety value.

As a further feature, the piercing member may be held in an inoperative position by a safety pin, such that only when the safety pin is removed can the piercing member be displaced into an operative position in which it pierces the disc. The piercing member may be manually displaceable or may be spring loaded.

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Still further, the distribution valve may have communication openings through which the gas flows to the resin and catalyst containers, these communication openings being blocked by the piercing member when it is in its inoperative position and being unblocked when the piercing member is in its operative position. Thus, the possibility of resin and catalyst coming into contact with one another in the distribution valve or the possibility of either entering the valve and blocking it is minimised.

As a further safety feature, the distribution valve may have a further disc which is located between an interior chamber and the exterior and which is designed to rupture if the distribution pressure within the chamber exceeds a predetermined value that is suitably larger than the intended distribution pressure.
Instead, the connecting hoses connecting the distribution valve to the resin and catalyst containers or the spray gun may be such that they burst if the pressure exceeds the predetermined value.

Those skilled in the art will appreciate that the reactants (the resin and catalyst) are in liquid form and thus pressure losses in the hoses connecting the resin and catalyst containers to the spray gun will be proportional to the velocity of the liquid in the hoses squared, the density of the liquids, the length of 2~9~
g the hoses and a friction factor. As it is desirable that the connecting hoses have the same length, pressure losses are balanced and minimised by varying the internal cross-sectional area of the hoses. Thus, the connecting hoses between the resin and catalyst containers and the spray gun have suitable internal diameters in accordance with the required proportion of reactants to be supplied to the spray gun and the reactants are then supplied to the spray gun, in the required proportion virtually independently of the distribution pressure.

It will be appreciated that the spray gun has a mixing chamber from which the mixture is sprayed. The distance to which mixed material will be sprayed (the projection distance) from the mixing chamber will be determined by the pressure in the mixing chamber.

In an attempt to ensure that the mixing ratio between the two reactants is maintained at a particular desired value, restrictive ducts may be provided between the mixing chamber and the hoses connecting the spray gun to the plastic bottles. These restrictive ducts may have suitable lengths and diameters so that there is, in use, a substantial pressure drop across the ducts.
Instead of using ducts, suitable orifices may be provided.

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--1 o --The apparatus may particularly be used to provide a phenolic foam, in which case the resin may be phenol formaldehyde, and the catalyst may be a phenol sl~lphonic acid. The gas propellant may be nitrogen or air.

It will be appreciated that the propellant container and the resin and catalyst containers may be of any suitable size and shape and of any suitable materials. In a particular embodiment, the resin and catalyst containers are plastic bottles which may be formed in one piece by blow moulding or from two bottle parts, each of which is hollow and, together form the bottle. The two bottle parts may be mated to one another by means of a ring. The two bottle parts may be identical and each bottle part may have a neck portion so that the bottle is open at both ends. The ends may then be closed with caps, each of which has a nipple whereby the bottle may be connected to the hoses. The bottle parts may be injection moulded or blow moulded and they may be of high density polyethylene or polypropylene.

Still further according to the invention there is provided a spray gun which comprises two parts, a first body part and a second part which defines a flow directing portion, a mixing chamber and a nozzle.

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The parts may be secured together in a suitable manner. Thus, they may be welded together, 7 they may be held together by a fastener such as a screw or they may clip together. In the latter case the body part may have a plurality of projecting legs with hooks at their end, with the other part having passages through which the legs may pass, the hooks thereof engaging a flange portion of the second part.

The body part may define three straight parallel supply passages through which catalyst, resin and gas propellant pass, in use. These passages may open out in a planar surface which mates with a cavity in the second part which defines the flow directing portion. This cavity may have two spaced parallel walls and two angled side walls that are also rounded and may open into a substantially cylindrical passage in which there are static mixing formations. The cylindrical passage may have at its free end, ie. the end remote from the cavity, a restriction which opens out into an exit section. The r~estriction should be smooth and have a converging half-angle in the order of 10 to 30 to minimise the possibility of an entrance recirculation bubble being formed,in use, which could induce clogging.

The cylindrical passage may constitute the mixing chamber. In use, two streams of reactants are directed into the cylindrical passage by the angled side .

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walls, and they impinge on one another in a first part of the passage, and thus mix with one another.

Two transverse valve members may be provided in two of the supply passages to control the flow of resin and catalyst. These valve members may be pivotal by means of an operating handle. Further, a nipple member may be provided for the third passage, which has a restricted opening defined therein. Thus, unless the gun gets clogged, there is a free flow path for the gas propellant through the gun.

By means of the invention, a portable phenolic foam dispenser is provided that is cheap, reliable and safe.

The invention is now described, by way of example, with reference to the accompanying drawings, in which:-Figure 1 shows a logic diagram of a portable . .
apparatus for dispensing a phenolic foam, in accordancewith the invention;
Figure 2 shows a plan view of a spray gun of the apparatus;
Figure 3 shows a side view of the spray gun;

Figure 4 shows a sectioned view of a body part of the spray gun;
Figure 5 shows a sectioned view of a nozzle part of 3~

the spray gun;
Figure 6 shows a sectioned view of a pressure ve!ssel assembly of the apparatus;
Figure 7 shows a longitudinally sectioned view of an upper body of a distribution valve used with the pressure vessel;
Figure 8 shows a sectioned view of the upper body along line VIII-VIII therein;
Figure 9 shows a longitudinally sectioned view of a lower body of the distribution valve;
Figure 10 shows a sectioned view of a reactant vessel assembly of the apparatus; and Figure 11 shows schematically how the apparatus is stored in a container.

Referring to Figure 1, a portable apparatus for dispensing a phenolic foam is designated generally by reference numeral 10. Generally, the apparatus comprises a propellant container in the form of a metal bottle 12 which contains nitrogen or air propellant 14 at a pressure of about 5 MPa, a resin container in the form of a plastic bottle 16 which has a volume of 8 litres and contains resin 18, a catalyst container in the form of a plastic bottle 20 which has a volume of 2,5 litres and contains catalyst 22, a distribution valve 24 which controls the distribution of propellant, a spray gun 26, a connecting hose 28 connecting the distribution valve 24 to the resin bottle 16, a hose 30 2 ~

connecting the distribution valve 24 to the catalyst bottle 20, a hose 32 connecting the distribution valve 24 to the spray gun 26, a hose 34 connecting the resin bottle 16 to the spray gun 26 and a hose 36 connecting the catalyst bottle 20 to the spray gun 26.

In the particular embodiment of the apparatus that is described, the resin is phenol formaldehyde and the catalyst is phenol sulphonic acid. The resin has a viscosity of 450 centipo1se and a density of 1,2 kg per litre. The catalys~ has a viscosity of 200 centipoise and a density of 1,4 kg per litre. As indicated above, the propellant bottle 12 provides propellant at a supply pressure of 5 Mpa. The distribution valve 24 has a first orifice 38 which has a diameter of 0.35 mm which decreases the pressure of the propellant to a distribution value of approximately 300 Kpa. The propellant is retained in the bottle 12 by means of a rupturable disc 40 which is ruptured when the apparatus 10 is to be used, by means of a piercing pin 42. The disc 40 is of hard brass having a thickness of about 0,05 mm. At all times there is an open flow path between the interior of the distribution valve 24 and the connecting hose 32 which connects the distribution valve 24 to the spray gun 26. The pin 42 is held in an inoperable position by a safety pin 44.

It is to be appreciated that the spray gun 26 ' ' will operate at a pressure, known as the application pressure, as a result of the pressure of the propellant 14 passing therethrough. Thus, the application pressure utilised within the spray gun 26 is also controlled by the first orifice 38 and a second orifice 52 in the spray gun 26, which has a diameter of 0,7 mm.

As will be seen below, when the piercing pin 42 is in its inoperative position, there is no communication between the connecting hoses 28 and 30 or between either of the hoses 28 and 30 and the interior of the distribution valve 24. Such communication can only take place when the piercing pin 42 is displaced to its operative position. It is also to be noted that the bottles 16 and 20 are normally not pressurised and that there is an open flow path between the hose 28 and the bottle 16, between the bottle 16 and the hose 34, between the hose 30 and the bottle 20 and between the bottle 20 and the hose 36. It will thus be appreciated, that when the safety pin 44 is removed and the disc 40 ruptured by the piercing pin 42, propellant 14 is supplied to the resin bottle 16 and the catalyst bottle 20 at a distribution pressure of approximately 300 Kpa.

The connecting hoses 28, 30 and 32 are of a suitable construction so that they will burst if the pressure therein increases significantly above 300 Kpa.
It will further be understood that the internal cross-2 ~

sectional areas of the hoses 28, 30 and 32 are not critical and must merely be suitably large to permit flow of propellant therethrough without any significant pressure drop.

On the other hand, the length and internal cross-sectional areas of the connecting hoses 34 and 36 are critical and are used to control the rate of flow of resin 18 and catalyst 22. It is desired that the flow rate of resin 18 be three times that of the catalyst 22 and it is also desired that the hoses 34 and 36 be of equal length. Thus, the hoses 34 and 36 have a length of 3 meters and the resin hose 34 has an internal diameter of 16 mm and the catalyst hose 36 has an internal diameter o~ 10 mm.

It will be appreciated that the distribution valve 24 is non-reversible, in the sense that once the disc 40 has been ruptured it is not possible to close off the bottle 12 and the propellant 14 therein will discharge.
' Turning now to the spray gun 26 it will be seen that it has an on-off valve 46 for controlling flow of resin 18 and a further on-off valve 48 for ~ controlling flow of catalyst 22. The valves 46 and 48 ; are operated together by means of a handle 50. The gun : 26 further has the orifice 52 which, as explained above, ., 2~6~

controls the application pressure together with the orifice 38. The spray gun 26 also has a resin duct 54 and a catalyst duct 56 for controlling the flow of resin 18 and catalyst 22. The ducts 54 and 56 both have a length of 30 mm, with the catalyst duct having an internal diameter of 2,5 mm and the resin duct having an internal diameter of 4,8 mm.

~ The spray gun 26 has a nozzle part.58 and it will be seen that the propellant 14 is supplied through .a straight passage 60 that is in line with and central to the nozzle part 58. It will be noted that the ducts 54 and 56 are also straight, with the duct 54 being on one side of the passage 60 and the duct 56 being on the other side. As is e~plained below, flow of resin 18 and catalyst 22 are deflected inwardly after they leave the ducts 54 and 56.

The nozzle portion 58 has a mixing chamber 62 in which there is a static mixer 64. The nozzle part 58 ` has an exit 66 with a restriction 68 between the exit 66 and the static mixer 64. The restriction is smooth and has a converging half-angle of 22,5.

It will thus be appreciated, that when the apparatus 10 is to be used, the safety pin 44 is removed, the piercing pin 42 is manually displaced to pierce the disc 40 and the handle 50 is displaced to 2 ~

open the valves 46 and 48. It is not possible for the operator to vary or control the pressure or flow of propellant. The resin 18 and catalyst 22 are displaced from their bottles 16 and 20 to the spray gun 26 where they are mixed and the mixture is sprayed from the spray gun 26 as directed by the operator. Although it is possible for the operator to close the valves 46 and 48 by operating the handle S0, this will not prevent propellant from venting through the spray gun 26 and, in the event that the operator should try and close off the exit 66 with his thumb or the like, there will be a build up of pressure in the hoses 28, 30 and 32 which will cause one of them to rupture.

The various components of the apparatus 10 are now described in more detail.

Referring to Figures 2, 3, 4 and 5, the spray gun 26 and parts thereof are shown. Referring initially to Figures 2 and 3, the handle 50 and the nozzle part S8 are shown. The gun 26 also has a body part 70 with three nipples, two of which , 72 and 74, being visible in Figure 2. The resin hose 34 is connected to the nipples 72 and the catalyst hose 36 is connected to the nipple 74. The nipple 72 and 74 have sizes which correspond with the internal diameters of the hoses 34 and 36 so that the hoses 34 and 36 cannot be connected to the wrong nipples 72 or 74 which in turn ensures that - l 9 -resin is supplied to the duct 54 and catalyst to the duct 56. As shown in Figure 3, the operating handle S0 is pivoted ~rom the inoperative position shown in solid lines, through 90 to the operative position shown in dotted lines. When the handle 50 is pivoted in this manner, two spindles are rotated. One of the spindles 76 is shown. When the spindles are rotated, a transverse bore in each spindle is rotated to be in line between the nipple 72, 74 and the duct 54, 56 respectively. When the spindles are in their inoperative position, they block the flow path between the nipples 72, 74 and the ducts 54, 56 respectively.

Referring to Figure 4, the body part 70 is shown in more detail. It will be noted that the body part 70 is made of high density polyethylene with 15%
glass fibre reinforcing. The nipples 72 and 74 are shown in Figure 4 together with the third nipple 78 to which the hose 32 is connected. It will be seen that the orifice 52 is located in the nipple 78 with the passage 60 being in line therewith. The ducts 54 and 56 are also shown and, as indicated above, the ducts 54 and 56 and the passage 60 are all straight and parallel to one another with the passage 60 being between the ducts 54 and 56. As indicated above, the ducts 54 and 56 and the passage 60 open out in a planar face 80.

Referring to Figure 5, the nozzle part 58 is 2~9~

shown. The nozzle part 58 is also of hiqh density polyethylene with 15% glass reinforcing. As seen in Figure 5, the nozzle part 58 has a frusto-conical portion 82 and a tubular portion 84.

The frusto-conical portion 82 has a recess defined by lips 86 with the end of the body part 70 defined by the planar face 80 being snugly received therein. The body part 70 and nozzle part S8 are secured together by means of an adhesive, welding or the like.

The frusto-conical portion 82 has two opposed parallel planar walls (one of which 88 is designated) and two angled rounded walls 90 and 92 to define a cavity. It will be appreciated that the angled wall 90 is aligned with the duct 54 and the other angled wall 92 is aligned with the duct 56 so that streams of resin 18 and catalyst 22 issuing from the ducts 54 and 56 are deflected by the angled walls 90 and 92 towards each other and towards the tubular portion 84.

The tubular portion 84 has the mixing chamber 62 which is circular cylindrlcal being defined by a cylindrical wall 94. It is to be noted that there is fairly sharp transition between the angled walls 90 and 92 and the cylindrical wall 94 respectively. Thus, ln use, the deflected streams of resin 18 and catalyst 22 2 ~

impinge on one another and with a stream of propellant 14 which flows from the passage 60 so that they mix well together, with further mixing being provided by the static mixer 64 (which is an insert and is not shown in Figure 5). Further, the resin 18 and catalyst 22 react with one another in the mixing chamber 62 and the mixture, with propellant bubbles therein, is discharged from the exit 66 as a foam.

- Figures 6, 7, 8 and 9 are now referred to.
Referring initially to Figure 6, the metal bottle 12 containing the propellant 14 and the distribution valve Z4 are designated therein. The bottle 12 is o~ an aluminium alloy.

The distribution valve 24 includes, as discussed earlier, the disc 40, the piercing pin 42 and the safety pin 44. The disc 40 is held between a lower valve body 96 and a disc holder 98. There is an O-ring 100 between the disc holder 98 and the lower valve body 96 the purpose of which is explained below. The lower valve body 96 and t:he disc holder 98 are both of brass.

It will be noted that the lower valve body 96 has an external screw-thread 102 by means of which it is screwed into the neck 103 of the bottle 12 and it also has an internal screw-thread 104 with the disc holder 98 having a complementary external screw-thread.

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An upper valve body 106, which carries the piercing pin 42, is screwed into the disc holder 98, the disc holder 98 having an internal screw-thread and the upper valve body 106 having a complementary external screw thread.

As is seen in Figure 6, the piercing pin 42 has a lower sharpened portion 108 with a slot 110 therein and a central portion 112 which is slightly larger than the lower portion 108. Finally, the piercing pin 42 has an upper portion 114 which is smaller than the central portion 112, there being a shoulder 116 between them. The safety pin 44 passes through a bore in the upper portion 114 and the upper portion 114 carries a knob 118. The pin 42 is also of high density polyethylene with 15~ glass reinforcing.

Referring in addition to Figures 7 and 8, it will be seen that the upper body 106 has two nipples 120 and 122 for the hoses 28 and 30 and a socket 124 into which an insert (not shown) is inserted, the insert having a further nipple to which the hose 32 is connected. The upper body 106 has an internal bore 126 which is transverse to the nipples 120 and 122 and the socket 124. The bore 126 has an internal step 128 which is slightly inward of the bottom edge of the socket 124.
A communication opening 130 is provided between the bore 126 and the socket 124 at the step 128 so that there is 2~98~

an unimpeded flow path between the bore 126 and the socket 124 even when the piercing pin 42 is in its inoperative position as shown in Figure 6. Passages 132 in the nipples 120 and 122 open out in a central part 134 of the bore 126, above the step 128. It will be understood that the central portion 112 of the pin 42 is located in the central part 134 of the bore 126 when the~
pin 42 is in its inoperative position. As the central portion 112 of the pin 42 is a snug fit in the central part 134 of the bore 126, there is no fluid communication between the passages 132 and between each passage 132 and a lower part 136 of the bore 126. It will further be appreciated, that when the pin 42 is displaced into its operative position in which it pierces the disc 40, the central portion 112 of the pin 42 passes into the lower part 136 of the borè 126 and the shoulder 116 together with the step 128 impede return of the central portion 112 of the pin 42 into the central part 134 of the bore 126, which would result in blocking of the passages 132. As seen in Figure 6, the pin 42 has a short groove 138 at the upper end of the central portion 112 to provide a flow path for propellant into the passages 132 even if the shoulder 116 abuts the step 128.

Referring to Figure 10 the resin bottle 16 is shown. The bottle 16 is of high density polyethylene and is formed from two identical parts 140 which mate .

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together and are welded together at mating ends 142.
1'he parts 140 each have a neck 144 that is externally screw-threaded. One end is closed by a cap 146 which has an integral nipple 148 that is connected, in use, to the hose 34. The other end is closed by a cap 150 and a separate nipple 152 which, in use, is connected to the hose 28. As indicated above, the resin bottle 16 has a volume of 8 litres.

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. The catalyst bottle 20 is similar in construction to the resin bottle 16, except that the two parts 140 are smaller and one end is closed with a cap similar to cap 146 but with a nipple that has a size complementary to the internal diameter of the hose 36.
Further, as indicated above, the catalyst bottle 20 has a capacity of 2,5 litres.

Referring finally to Figure 11, it is shown that the apparatus 10 also includes a case 154 which has carrying straps 156. The bottles 12, 16 and 20, the .:
various hoses and the spray gun 26 being stored in the case 154. It will be noted that the bottles 16 and are stored in an upright manner, with their nipples 152 to which the hoses 28 and 30 are connected being on top, so that the propellant 14 displaces the resin 18 and catalyst 22 out of the other, bottom ends of the bottles 16 and 20.

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It will be noted that the bottle 12 is filled ~ith propellant in the following manner. The lower body 96 is screwed into the neck 103 of the bottle 12, the disc 40 is placed in position and the disc holder 98 is screwed into the lower body 96. However, the disc holder 98 is not screwed down tightly and a suitable connector (not shown) connected to a supply of nitrogen or air under pressure, is screwed into the disc holder 98.
Nitrogen is supplied, and flows past the disc 40 into the bottle 12. When the bottle 12 is filled to the required pressure, the disc holder 98 is screwed down tightly thereby gripping the disc 40 in a sealing manner. The connector is removed and the upper body 106, with the piercing pin 42 therein is screwed into the disc holder 98.

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Claims (29)

1. A portable apparatus for supplying and dispensing a settable foam mixture which includes a high pressure propellant container which is a metal bottle which, in use, contains a gas propellant;
a pair of low pressure plastic containers one of which, in use, contains resin and the other, in use, contains catalyst;
a spray gun for mixing the resin and catalyst and for spraying the resulting mixture;
connecting hoses for connecting the metal bottle to each of the plastic containers and for connecting the metal bottle and both plastic containers to the spray gun; and a valve means for controlling the flow of propellant from the metal bottle to the plastic containers and from the metal bottle to the spray gun, and the flow of resin and catalyst through the spray gun.

2. The portable apparatus claimed in Claim 1 in which the metal bottle contains a gas propellant which is at a supply pressure of about 5MPa while both the plastic bottles are unpressurised.

3. A portable apparatus for supplying and dispensing a settable foam mixture which includes a propellant container;
a propellant at a suitably high pressure contained within the propellant container;
an unpressurised resin container;
resin contained in the resin container;
an unpressurised catalyst container;
catalyst contained in the catalyst container;
a spray gun;
a connecting means for connecting the propellant container to the spray gun, the resin container and the catalyst container;
connecting hoses connecting the resin container and the catalyst container to the spray gun; and a valve means between the propellant container and the connecting means for supplying, in use, propellant to the resin and catalyst containers and the spray gun at a reduced pressure.

4. The apparatus claimed in Claim 3, in which the valve means includes a distribution valve for controlling the supply of propellant, in use, to the resin container, the catalyst container and the spray gun.

5. The apparatus claimed in Claim 4, in which the propellant container is at a supply pressure of about MPa and the distribution valve is such that it supplies propellant to the resin container, the catalyst container and the spray gun at a distribution pressure of about 300 KPa.

6. The apparatus claimed in Claim 4, in which the distribution valve has a first orifice which restricts the flow of gas from the propellant container to provide the required drop in pressure.

7. The apparatus claimed in Claim 3, which includes an application pressure control means for controlling the application pressure of propellant utilized, in use, within the spray gun.

8. The apparatus claimed in Claim 7, in which the application pressure control means includes a first orifice and a second orifice, the first orifice being located at the propellant container and the second orifice being spaced therefrom and being between the propellant container and the interior of the spray gun.

9. The apparatus claimed in Claim 8, in which the second orifice is located at the spray gun end of a hose connecting the propellant container to the spray gun.

10. The apparatus claimed in Claim 8, in which the second orifice is located within a component of the spray gun.

11. The apparatus claimed in Claim 3, in which the valve means is a non-reversible distribution valve.

12. The apparatus claimed in Claim 11, in which the non-reversible distribution valve has a disc and a piercing member to pierce the disc when the apparatus is to be used.

13. The apparatus claimed in Claim 12, in which the disc is such that, if the pressure in the propellant container exceeds a predetermined value, it ruptures, and in which there is defined an unimpeded flow path from the disc to the outlet of the spray gun.

14. The apparatus claimed in Claim 12, in which a control orifice is located between the disc and the interior of the propellant container, so that gas is released from the propellant container in a controlled manner.

15. The apparatus claimed in Claim 12, in which the piercing member is held in an inoperative position by a safety pin, such that only when the safety pin is removed can the piercing member be displaced into an operative position in which it pierces the disc.

16. The apparatus claimed in Claim 12, in which the distribution valve has communication openings through which the gas flows to the resin and catalyst containers, these communication openings being blocked by the piercing member when it is in its inoperative position and being unblocked when the piercing member is in its operative position.

17. The apparatus claimed in Claim 12, in which the distribution valve has an interior chamber and a further disc located between the interior chamber and the exterior and which is designed to rupture if the distribution pressure within the chamber exceeds a predetermined value that is suitably larger than the intended distribution pressure.

18. The apparatus claimed in Claim 12, in which connecting hoses connecting the valve to the resin and catalyst containers are such that they burst if the pressure therein exceeds a predetermined safety value.

19. The apparatus claimed in Claim 3, in which the spray gun has a mixing chamber from which the mixture is sprayed.

20. The apparatus claimed in Claim 19, which has restrictive ducts between the mixing chamber and hoses connecting the spray gun to the resin and catalyst containers, the restrictive ducts having suitable lengths and diameters so that there is, in use, a substantial pressure drop across the ducts.

21. A spray gun which comprises two parts, a first body part and a second part which defines a flow directing portion, a mixing chamber and a nozzle.

22. The spray gun claimed in Claim 21, in which the body part defines three straight parallel supply passages through which catalyst, resin and gas propellant pass, in use.

23. The spray gun claimed in Claim 22, in which the passages open out in a planar surface which mates with a cavity in the second part which defines the flow directing portion.

24. The spray gun claimed in Claim 23, in which the cavity has two spaced parallel walls and two angled side walls which are rounded and which open into a substantially cylindrical passage in which there are static mixing formations.

25. The spray gun claimed in Claim 24, in which the cylindrical passage has, at the end thereof which is remote from the cavity, a restriction which opens out into an exit section, the restriction being smooth and having a converging half-angle of between 10° and 30°.

26. The spray gun claimed in Claim 24, in which the cylindrical passage constitutes the mixing chamber.

27. The spray gun claimed in Claim 21 in which two transverse valve members are provided in two of the supply passages to control the flow of resin and catalyst.

28. The spray gun claimed in Claim 22, in which the third passage has a nipple member, which has a restricted opening defined therein.

29. The apparatus claimed in Claim 3, in which the spray gun is as claimed in any one of Claims 21 to 28.