Abstract: A programmable circuit detects drop in pressure of a supplied pressurized gas below a predetermined threshold pressure and automatically switches to a different supply of pressurized gas and automatically contacts a remotely located host computer. The circuit sends status data to the host computer and enters a server mode in which the circuit performs commands issued by the host computer. The commands include commands to change data of the programmable circuit and to download new programming. The predetermined threshold pressure is established by manually setting the supplied pressurized gas to a desired pressure and causing the programmable circuit to measure the pressure of supplied gas and to store the measured pressure as the threshold pressure.

Abstract: A programmable circuit detects drop in pressure of a supplied pressurized gas below a predetermined threshold pressure and automatically switches to a different supply of pressurized gas and automatically contacts a remotely located host computer. The circuit sends status data to the host computer and enters a server mode in which the circuit performs commands issued by the host computer. The commands include commands to change data of the programmable circuit and to download new programming. The predetermined threshold pressure is established by manually setting the supplied pressurized gas to a desired pressure and causing the programmable circuit to measure the pressure of supplied gas and to store the measured pressure as the threshold pressure.

Abstract: An automatically switching valve measures pressure at an outlet line using an electric, pressure-sensitive switch which can be set to close at a predetermined pressure threshold within relatively narrow tolerances such that a pressure regulator can be placed between the pressurized gas supply tanks and the switching valve. Closing of the pressure-sensitive switch in response to the drop in pressure below the predetermined threshold sends an electric signal to a relay. In response to the electric signal, the relay causes a different inlet line to be selected, thus changing the particular pressurized gas supply from which the outlet line receives pressurized gas. When gas is supplied through a first inlet line, an electric signal from the pressure-sensitive switch causes the relay to toggle to supply gas through a second inlet line. A subsequent signal from the pressure-sensitive switch causes the relay to toggle back to again supply gas through the first inlet line.