Apparatus and method for producing and dispensing a reaction mixture

An apparatus for producing and dispensing a reaction mixture starting from at least a first reaction component and a second reaction component that are under a first pressure in a first container and a second pressure in a second container respectively, the apparatus comprising:

• a mixing head configured for mutually mixing said first reaction component and said second reaction component, wherein the mixing head comprises an outlet configured for the mixture of first and second reaction components;
• a first supply line configured for feeding the first reaction component from said first container under the first pressure prevailing therein to the mixing head;
• a second supply line configured for feeding the second reaction component from said second container under the second pressure prevailing therein to the mixing head;
• a first shut-off valve in said first supply line and a second shut-off valve in said second supply line, the first shut-off valve and the second shut-off valve each having an open position and a closed position;
• a third shut-off valve configured for shutting off the first supply line in said mixing head and a fourth shut-off valve configured for shutting off the second supply line in said mixing head, the third shut-off valve and the fourth shut-off valve comprising a common plunger configured to slide, for opening and closing the third shut-off valve and the fourth shut-off valve simultaneously;
• a first expansion chamber connected to the first supply line between said first shut-off valve and said third shut-off valve;
• a second expansion chamber connected to the second supply line between said second shut-off valve and said fourth shut-off valve;
• a pneumatic system configured for the pressurization and pressure-relief of the first expansion chamber and of said first supply line as from said first shut-off valve to said third shut-off valve, and for the pressurization and pressure-relief of the second expansion chamber and of said second supply line as from said second shut-off valve to said fourth shut-off valve;
• and
• a control system configured for operating said pneumatic system and said first, second, third and fourth shut-off valves for starting and stopping production and dispensing of said reaction mixture,
• wherein said first expansion chamber and said second expansion chamber, respectively, are formed by a first pressure vessel and a second pressure vessel having each two sides separated from each other by a membrane, of which a first side forms the first expansion chamber and respectively the second expansion chamber, configured to be filled with said first reaction component and respectively said second reaction component, and of which a second side is connected to said pneumatic system and configured to be filled with a gas, which gas is in contact through said membrane with the respective first reaction component and the second reaction component in the first side;
• wherein said pneumatic system is provided to bring the first expansion chamber under a third pressure which is higher than said pressure in the first container and to bring the second expansion chamber under a fourth pressure which is higher than said pressure in the second container;
• wherein said membrane is convex, the convex side of the membrane being directed respectively towards the first and the second expansion chamber, and the first and the second pressure vessel being provided with a support surface for limiting the movement of said membrane in the direction of respectively said first and said second expansion chamber, with the membrane being pressed against the support surface when the first reaction component is fed from said first container under the pressure prevailing in the first container to the mixing head and when the second reaction component is fed from said second container under the pressure prevailing in the second container to the mixing head;
• and
• wherein said first pressure vessel and said second pressure vessel are detachably connected to said pneumatic system and to the first supply line and the second supply line respectively.