Inventors:
Howard B. Pritz - Columbus OH
Sherwood G. Talbert - Columbus OH
Assignee:
SmithKline Corporation - Philadelphia PA
International Classification:
A61M 530
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.