Abstract: A control system for a diffusion pump is provided which serves to protect the pump from loss of the pumping fluid, from loss of water cooling, as well as from overheating of the heater. The protective system includes a thermally responsive switch mounted on a heat-conductive bracket, and which responds to the temperature of the cooling water as well as to heat radiated from the heater to turn off the electric current to the heater when either the temperature of the cooling water or the heat radiated from the heater rises above a predetermined value. The control system also includes a heater block surrounding the heater, and which is composed of a material having a relatively low melting point as compared with the melting point of the material forming the containment vessel of the pump, so that overheating of the heater will cause the block to melt and to be displaced from the bottom of the containment vessel to reduce heat transfer to the pump.

Abstract: A metering and control system is provided which in one embodiment provides a continuous reading vacuum gage and a controller for activating relays when the vacuum pressures indicated by the gage pass through one or more set points. The controller comprises solid state electrical control circuitry which is separate from the meter, and which may be switched into the meter circuit for calibration purposes. The control circuitry is made up of individual circuits which may be individually adjusted to selected set points, as indicated on the meter. For this purpose, the meter is selectively switched to the various individual circuits. Then, the meter is switched back to indicate the vacuum pressures encountered in the particular system in which it is installed. As the vacuum pressures pass the various set points, the corresponding relays are activated.

Abstract: A valve is provided which includes a poppet enclosed in a plug of plastic material, such as Teflon, and which is biased against a seat by a compression spring so that a positive seal is provided even in the presence of cold flow in the plastic plug. A valve stem engages the poppet, and it serves to pull the poppet and plug away from the seat against the force of the spring when the valve is opened, and to force the poppet and plug against the seat when the valve is closed. The valve may be hand operated, or it may be operated by a pressurized fluid, such as air. An indicator is included in the assembly which provides a readily visible indication of any leakage within the valve housing.

Abstract: A gate valve is provided for use in conjunction with vacuum equipment in which a gate assembly is opened and closed, for example, by a pneumatic cylinder. The gate assembly is enclosed in a valve housing, and aligned openings are provided in the opposite walls of the housing. The gate assembly is moved by the pneumatic cylinder between an open and closed position with respect to the openings. The gate assembly includes a gate which is mounted on a carriage, and the carriage is moved by the pneumatic cylinder between a first position in which the gate is open, and a second position in which the gate is closed. A feature of the gate valve of the invention is that when the gate is open, a smooth bore is provided through the valve aperture with electrical surface conductivity for short-circuiting stray radio frequency electric currents.

Abstract: A valve is provided which includes a poppet enclosed in a plug of plastic material, such as Teflon, and which is biased against a seat by a compression spring so that a positive seal is provided even in the presence of cold flow in the plastic plug. A valve stem engages the poppet, and it serves to pull the poppet and plug away from the seat against the force of the spring when the valve is opened, and to force the poppet and plug against the seat when the valve is closed. The valve is closed by a pressurized fluid, such as air, and is opened by means of a spring when the air pressure is removed. The Teflon plug is provided with a sharp corner which contacts a conical seat creating a seal when the valve is closed. The sharp corner of the plug wipes the seat of the debris as the valve is opened and closed.