the basic dispensing system for a single colour paint is shown in fig1 and comprises a recirculation loop 1 around which the paint is continuously circulated under pressure by a pump 2 from and back to storage tank 3 . disposed in the loop 1 is a three - way control valve 4 which can be selectively operated to divert paint from the loop 1 into branch line 5 to dispensing valve 6 and from there into a container 7 ( fig2 and 5 ). referring more particularly to fig2 the dispensing machine itself comprises an inner casing 8 within which is disposed a pedestal 9 for supporting the paint container 7 at a filling station . in an alternative embodiment , the pedestal 9 can be replaced by a transporting conveyor which periodically stops when a container is at the filling station to allow the paint to be dispensed into it . the upper end of the pedestal 9 constitutes a weighing scale 10 for weighing the amounts of paint fed by the valves 6 to the container 7 . an outer casing 12 surrounds the inner casing 8 and within this are disposed a series of the three - way valves 4 corresponding in number to the maximum number of basic colours to be dispensed by the machine . each of the valves 4 has a respective pneumatic actuator 13 . a respective branch line 5 leads from each valve 4 to a respective dispensing valve 6 . each of the valves 6 is of a slim elongated tubular design with a nozzle 14 at its lower end through which the paint is ejected into the container 7 . from an inspection of fig2 and 6 it can be seen that the valves 6 are arranged in an inverted conical formation with the nozzles 14 directed towards the apex of the cone , which lies within the container 7 and on the central vertical axis 15 thereof . in this particular example there is a group of thirty - seven dispensing valves 6 . to provide the conical arrangement of the valves 6 , they are mounted in respective bores of a common mounting block 16 which is supported on the top of inner casing 8 . in fig5 and 6 are shown the position which two different sized containers referenced 7a and 7b would have relative to the nozzles 14 . the construction of the dispensing valves is best seen in fig3 and 4 . a valve stem 18 is slidable in an outer elongated tubular valve body 19 and is biased by spring 20 to a closed position in which the conical valve member 22 at the lower end of the stem 18 is urged into engagement with conical seat 23 at the nozzle 14 to close off outlet nozzle orifice 24 . the valve stem 18 has a central bore 25 which terminates at its lower end in transverse bores 26 and 27 . the upper end of the bore 25 provides a liquid inlet to the valve 6 and connects with one of the feed lines 5 . thus when the associated three - way valve 4 is operated paint flows along the feed line 5 , through the bore 25 and out of the transverse bores 26 and 27 into the annular space 28 within the interior of the body 19 between the valve stem 18 and the lower part of the body 19 . the valve stem 18 is provided intermediate its ends with a piston formation 29 which is a close sliding fit in the upper part of the body 19 . the periphery of the piston 29 has two ` o ` rings which provide liquid - tight seals preventing paint escaping upwardly past the piston 29 . when the associated control valve 4 is operated the flow of pressurised paint first fills the annular space 28 and then acts on the lower face of the piston 29 to cause it to move upwardly against the spring bias and thus corresponding upward movement of the valve stem 18 to cause the valve member 22 to move away from the valve seat 23 to fully open the valve to the position shown in fig4 so that the paint passes through the orifice 24 into the container 7 . as soon as the pressurised paint supply to the valve 6 is stopped by operation of the valve 4 to close off the feed line 5 , the valve 6 is instantaneously closed under spring pressure . advantageously the weighing scale can be interfaced with a computer which controls the actuation of the pneumatic valves 13 to close off the paint supply to the container when the predetermined weight of paint has been delivered . in this way various refinements can be incorporated into the dispensing system by writing them into the computer software . although in the particular example there are thirty - seven dispensing valves , this number is to some extent arbitrary but arises from the geometric pattern shown in the plan view of fig6 where one valve is at the centre , six in the next ring twelve in the next ring , eighteen in the next ring and so on . it is not necessary to have each valve the same size though this is naturally convenient . it could be that one or two or more valves are of a larger size for a particular application . for example , the centre valve may be very much larger than the others and used to supply the white paint which is normally required in larger quantities . the valves 6 are as previously stated mounted in a machined block 16 . the advantage of the particular construction and arrangement of the dispensing valves as described is that they can be made by automatic machining processes and are therefore low cost items which are simply popped into the mounting block and secured with a clip . this is a very important feature in use , since any maintenance problems can be very quickly dealt with by changing a valve rather than repairing it . a lot of valves on the market for use in paint blenders appear to have been influenced by the design of automotive poppet valves as used in most motor cars . in this type of valve the valve stem or the male member moves away from the end of the valve body outside the valve body in order to open . this is an advantage in automobile engine design since the shape of the valve when open helps to spread the gas and the fuel charge around the cylinder . when this type of valve is used for dispensing paint it has a definite disadvantage , since the paint is directed into a divergent flow pattern which can cause excessive splashing . equally if the valve does not open absolutely concentrically then one can get a jet of paint emerging preferentially from one side of the valve . this is not a trivial problem and indeed several examples are on the market where this phenomena presents itself and causes a considerable nuisance . the controlling area for dispensing the paint is the area of the nozzle orifice . for maximum direction of the jet a convergent i . e . conical nozzle is required and therefore the actuated part i . e . the valve member must move inwards of the valve body towards the wider part of the cone . given these two factors the design is carefully tuned so that the annular area 32 between the conical valve member 22 and the valve body 19 on the valve stem is equal to the area of the nozzle orifice 24 when the valve is in the position shown in fig4 . a feature of the design is therefore that the minimum overall area is achieved throughout by very careful matching of areas so that no part of the valve is bigger than it actually has to be in order to match other parts of the valve . there are several advantageous reasons for the conical layout of the dispensing valves 6 . one is that if one packs a number of nozzles together into the minimum possible area at the tip of the nozzles then they naturally tend to form a conical shape . the second reason for doing this is that it is an advantage to direct the paint to the centre of the container rather than simply to let it fall vertically downwards when it is near to the edge of the container . the third reason and possibly the most important ultimately is that the conical layout enables larger parts of the valve to be fitted on to a bigger pitch circle diameter . thus if one needs relatively bulky springs or actuators fitted to the valve then these can be located at the opposite end of the valve to the nozzle where there is more space and where use of this space does not prejudice the ability to load a small container . in the particular example shown , the valves are of simple conical shape and they are all directed towards the intersection of the x and y axes shown in fig6 . one could have a variant on this where the angles of the cone are compounded such that one could , if one wished , promote swirl by arranging the valves in a conical pattern , but aimed at some point off the centre of the container when viewed in plan . since all dispensing valves are present over the container it is not necessary to move either the valves or the container in order to direct a number of paint streams to the container . this represents a very considerable advantage over other machines which are currently on the market . since the rate of discharge is related to the size of the container it is perfectly possible to scale up this design such that if the container was 1 tonne size than 1 liter size then the valves would be larger in diameter but the arrangement would be the same and simply on a larger scale . in the above described system , the valves 6 can open by anchoring the stem 18 and allowing the valve body to move downwards relative to the valve stem . alternatively one can choose to anchor the valve body and permit the stem to move . one of the most significant features of the above described system is that the dispensing valves do not need mechanical actuation at all . the valves are designed to be actuated by the hydraulic pressure of the paint . thus there are very few moving parts in the valve and very little to go wrong . since it is so simple it is very cheap to make . a particular feature of the system described above is that the valve is very unlikely to leak when it is supposed to be closed . in most commercially available valves the pressure is still on the valve after the valve has closed and any small imperfections in the seating face will cause a leak . in the present system , however , the closing mechanism is simply one of falling pressure . in other words when the end of the dispense is reached the actuated three way valve is positioned so that paint flows back to the tank , the pressure drops in the line leading to the valve and the valve closes . thereafter there is very little that can happen to cause the valve to leak . there is no pressure transmitted across the actuated three - way valve , hence the route back to the tank has been made easy and there is a considerable sealing force generated by the spring in the dispensing valve and nothing being supplied to overcome the force of that spring . in fact , with this particular design where the pressure is removed upstream of the valve when the valve is not required to operate , one has a situation where the valve is very unlikely to leak even if the valve seating became damaged a little by the odd paint particle or any other foreign body . a further feature of the design of dispensing valve is that when closed the valve has the absolute minimum possible surface area available for paint to dry upon . secondly as the valve closes it tries to expel the remaining drops of paint which is different to the other valves where the closing of the valves tends to splash paint on to the body of the valve . if paint is allowed to collect on the bottom of the valve it can build up and eventually form stalactites and in any case it is a nuisance since it can cause contamination . the most practical way to limit contamination is firstly to prevent the paint sticking there in the first place and then to limit the surface area such that if paint does stick there it is very small and minimal amount .