Abstract: An apparatus for blending two gases together in precisely adjustable proportions. The apparatus includes a mechanically adjustable, blending subassembly adapted to receive the first gas at a predetermined pressure and a one-to-one force balanced pneumatic relay which is operated by the first gas and which meters the flow of the second gas to the blending subassembly at a pressure substantially equal to the pressure of the first gas being supplied to the blending subassembly. Check valves are strategically located to prevent back flow of either of the gases being mixed when the device is being operated in the low-flow mode, thereby eliminating the requirement for time consuming balancing of the gas flow pressures.

Abstract: A safety flow control device for use in a beverage distribution system of the character using pressurized gas to dispense the beverage from its containers for ensuring that the containers are not accidentally overpressurized. The device of the invention is adapted to be placed in the line which connects the pressure source to the containers for the beverage. The device embodies a rupture disc having a first side exposed to the gas used in pressurizing the containers and a second side exposed to atmosphere. Strategically positioned between the pressure inlet of the device and the pressure side of the rupture disc is a valving mechanism which is maintained in an open configuration by the rupture disc. In the open configuration the valving mechanism permits the gas to flow from the inlet into a first sub-chamber defined by the first side of the rupture disc and then outwardly through the outlet of the device.