1. Wide measuring pressure range: 105 to 10-14 Pa.
2. Most vacuum gauges make indirect measurements. When the pressure is 105 to 10 Pa, the force per unit area can be directly measured. However, most vacuum pressures need to be measured are smaller than those described above and cannot be measured directly. Indirect measurements should be made using certain characteristics (such as heat conduction, viscosity, and ionization) of gases at low pressure.
3. Non-electricity quantity measurement technology is adopted mostly. Since non-electricity quantity measurement technology has the advantages of high sensitivity, rapid response, automatic and long-distance measurement, etc., most vacuum gauges use this method. The electronic vacuum gauge is composed of two parts, vacuum gauge control and electronic measurement circuit (control and indication unit). Gauge is a sensitive element. It utilizes certain characteristics of the gas under low pressure to convert the non-electrical gas pressure into an electrical signal. The measuring circuit then amplifies and displays the output electrical signal. When necessary, the output signal will be sent to the automatic recorder and automatic control equipment to achieve vacuum equipment automation. The conditions required to regulate the conversion of non-electrical pressure into electricity are provided by the control unit of the measurement circuit.
4. The reading of the partial vacuum gauge is related to the type and composition of the gas. Therefore, special attention must be paid to the type and composition of the gas during measurement, otherwise it will cause a great error.
5. The measurement accuracy is not high. Indirect measurement of pressure often requires additional energy to assist. The added energy may be thermal energy, electrical energy, mechanical energy, and radioactive energy. In this way, measurement errors are inevitably introduced at the same time as the introduction of additional energy. Therefore, vacuum gauges are less accurate than other physical gauges. For example, if the uncertainty of the vacuum measurement reference meter and the standard instrument is (2~10) ×10-2, the measurement error of the working instrument is within ±20×10-2.