Research and Application of Critical Nozzles in Vacuum Pump Speed Testing and Measurement

There are various methods for measuring the pumping speed of vacuum pumps, and their accuracy is affected by methods, instrument accuracy, and other factors. The constant flow method, as one of the methods, is based on the theory of compressible fluids in one element. The article combines the basic theory of one-dimensional compressible fluids with existing testing methods, proposing to use the critical state of the nozzle as the basis for measuring the constant flow rate method. By the appearance of the critical state of the nozzle and the calculation of the critical value, as the benchmark value for measuring the flow rate of the vacuum pump, only environmental parameters need to be measured during the measurement process to determine the flow rate of the vacuum pump, and then determine the pumping speed of the vacuum pump at a specified pressure. This measurement method has a simple device and process, is easy to operate, and the influence of external factors is naturally minimized. It is a reliable and green measurement method. As the most important parameter of vacuum pumps, digital and intelligent measurement is the development direction. Accurate pumping speed measurement is the basis for optimizing vacuum pumps and systems, which will promote the development of vacuum technology.