Gauge, vacuum capacitance manometer

The steam feeding of the chamber is under the full control of the programmable logic controller (PLC) and data acquisition is achieved by the SCADA system during sterilization cycle control. Vacuum gauges are adapted to function in saturated steam and ambient conditions (MKS capacitance manometer 621). 

The mechanical phenomena gauges measure the actual force exerted by the gas. They include a U-tube, a capsule dial, a strain, a capacitance manometer, a McLeod gauge, etc. Vacuum is measured according to the displacement of an elastic material or by measuring the force required to compensate its displacement. The measurement ranges from atmospheric pressure to 102 Pa in rough vacuum conditions. 

For many applications, gas-phase samples can be prepared using a routine vacuum line consisting of mechanical and diffusion pumps, a cold trap, thermocouple and capacitance manometer gauges and a manifold with attachments for sample tubes and gas inlets. NMR sample tubes are either sealed with a glass torch or constructed with self-sealing top assemblies. Preparation of samples at elevated pressures requires quantitative transfer operations. With few exceptions, gas-phase NMR samples used to study conformational processes contained a volatile bath gas in addition to the sample molecule, which usually has a low vapour pressure. Molecules with low vapour pressures tend to behave nonideally even at very low pressures and this factor must be taken into consideration when converting measured gas pressures into densities. 

Capacitance manometer (vacuum technology) A vacuum gauge that uses the deflection of a diaphragm, as measured by the changing capacitance (distance) between surfaces, as an indicator of the pressure differential across the diaphragm, the pressure on one side being a known value. See also Vacuum gauge. 

Figure I. A typical high-vacuum setup for Li. 22(NHj),TiS5- " synthesis. The manometer pressure gauge (either a capacitance manometer or a Hg manometer, preferably with a thin layer of ultra-low-vapor-pressure oil on top of the Hg column to suppress Hg volatility) is used to monitor the gas pressure and ensure the NH3 pressure does not exceed ambient pressure at any time.

Medium vacuum (25-1 x 10 Torr) is vacuum that can be achieved with a single pump, but the pressure cannot be measured by liquid or mechanical manometer. The pressure can be measured with a thermal gauge or a capacitive gauge. 

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