1. Pressure measurement range：105~10-14 Pa.
2. Most of the vacuum gauge is indirect measurement, and the force of the unit area can be measured directly only when the pressure is 105 to 10Pa. However, most vacuum measurement pressure is small than the above mentioned, cannot be measured directly, should be used some characteristics of the gas under low pressure (such as heat conduction, viscosity and ionization, etc.) for indirect measurement.
3. Non-electric measurement technology is adopted. Due to the non-electrical measurement technology with high sensitivity, fast response, automatic and long-range measurements can be achieved, most of the vacuum gauge using this method. An electronic vacuum gauge is composed of two parts of a vacuum gauge and an electronic measuring circuit (control and indicator unit). The gauge is a sensitive element. It transforms the gas pressure of non electric quantity into electrical signal by using some characteristics of the gas under low pressure, and then amplifies and displays the output electrical signal of gauge by the measuring circuit. When necessary, the output signal is sent to the automatic recorder and automatic control equipment to realize the automation of the vacuum equipment. The requirements for converting non-electric pressure into electric charge are provided by the control unit of the measurement circuit.
4. The readings of some vacuum gauges are related to the type and composition of the gas. Therefore, measurement should pay special attention to the type and composition of the gas while measuring; otherwise it will cause a great error.
5. Measurement accuracy is not high. In the process of indirect measurement of pressure, additional energy is often needed to assist. The external energy may be thermal energy, electrical energy, mechanical energy and radiological energy. In this way, the measurement error is inevitably introduced at the same time as the applied energy is introduced. Therefore, the precision of the vacuum measuring instrument is lower than that of other physical measurement instruments.