Abstract: A flue restrictor for installation in the flue piping of a heating system to reduce its effective cross sectional area comprises sheet metal inlet and outlet sections having flanges secured together in a joint that has a guideway in it for a sheet metal gate valve that may be transversely positioned to produce the desired cross-sectional area and riveted in place to provide a substantially tamper-proof assembly.

Abstract: A method of forming an ampul comprises drawing an aluminosilicate glass tube containing alkali metal ions and having the inner and outer diameter desired for the body of the ampul to reduce the diameter and provide a portion having an inner diameter in the range of from about 0.007 to about 0.03 cm. Advantageously the transition shoulder portion extending from the full diameter to the reduced diameter is heated while rotating and then subjected to axial compression to partially collapse it. The reduced diameter portion of the tube is then severed to form an ampul with a body having the inner and outer diameters of the original tube and a discharge passage which has a discharge opening with a diameter in the range of from about 0.007 to about 0.03 cm. and which has a length at least ten times the diameter of the discharge opening. The drawing provides for a small taper in the discharge passage which preferably will have a diameter equal to from about 2 to about 1 times the diameter of the discharge opening.

Abstract: A pressure operated injection device supports an ampul containing a plunger. A ram which actuates the plunger is spring biased to a retracted position and is advanced by a gas under pressure. A source of gas under pressure is connected by a passage to a gas accumulating chamber which in turn is connected by a passage to the ram with a valve being provided in each passage. The valves admit gas to the ram from the accumulating chamber at a predetermined pressure and simultaneously prevent the admission of any further gas from the source of gas and, at a substantially lower pressure, close the passage connecting the accumulating chamber and the ram. The device is constructed to exhaust gas to the atmosphere from the ram as it retracts and a manually controlled valve controlling the flow of gas from the source to control the operation of the device.

Abstract: A unit dose ampul for a jet injector has a tube open at one end and an integral nozzle at the other end with a piston in the tube to seal the open end of the tube and to advance liquid in the tube through the nozzle. A sealing cap encompasses the nozzle and the forward end of the tube and is secured to the tube, the cap having a peripheral area of weakness adjacent the nozzle of the ampul whereby a portion of the cap can be broken off to expose the end of the nozzle. The cap has an interlocking portion for removably securing the cartridge to a jet injector.