What is the structural principle of a vacuum pump?

Piston reciprocating vacuum pumps, dry screw vacuum pumps, claw vacuum pumps, rotary vane vacuum pumps, water ring vacuum pumps, etc., create a vacuum by using mechanical mechanisms to extract gas, whereas steam jet pumps and water jet pumps extract gas through jets.

Based on the working principle of vacuum pumps, they can basically be divided into two types: gas transfer pumps and gas capture pumps. A gas transfer pump is a type of vacuum pump that continuously draws in and expels gas in order to achieve pumping purposes. A gas capture pump is a type of vacuum pump that adsorbs or condenses gas molecules on the inner surface of the pump, thereby reducing the number of gas molecules in the container and achieving the purpose of evacuation. 　　A vacuum pump is a device that uses various methods to create, improve, and maintain a vacuum in a closed space. A vacuum pump can be defined as a device or apparatus that uses mechanical, physical, chemical, or physicochemical methods to evacuate a container in order to create a vacuum. With the development of vacuum applications, a wide variety of vacuum pumps has been developed, with pumping speeds ranging from a few tenths of a liter per second to hundreds of thousands or even millions of liters per second. Based on the working principle of vacuum pumps, they can basically be divided into two types: gas transfer pumps and gas capture pumps. As the requirements for the pressure range in which vacuum application technologies are used in production and scientific research become increasingly broader, it is often necessary to use vacuum pumping systems composed of several types of vacuum pumps working together in order to meet the needs of these processes. Given the wide range of working pressures encountered in vacuum applications, no single type of vacuum pump can be suitable for all such pressure ranges; instead, different types of vacuum pumps must be used depending on the specific working pressure range and the requirements of the task at hand. For ease of use and to meet the requirements of various vacuum processing processes, different vacuum pumps are sometimes combined based on their performance characteristics and used in the form of units.

1. Reciprocating vacuum pump: It functions like a syringe connected to a T-shaped tube, with two check valves – one for suction and one for discharge – that move the plunger back and forth to create a vacuum at the suction end. 2. Rotary vane vacuum pumps draw in air, and the centrifugal force generated by the rotating vanes expels the air (gas) through the exhaust port; common vacuum cleaners fall into this category. 3. Water ring vacuum pump: It utilizes high-speed water flow passing through a nozzle-shaped outlet pipe; the high-speed water flow creates negative pressure, which draws out gases and thus generates a vacuum. Since water is used, the degree of vacuum is limited by the vapor pressure of water; in other words, water vapor is present in the resulting vacuum.

Under normal circumstances, the liquid ring vacuum pump is the most commonly used type; in this pump, the gas drawn in at the inlet is mixed with the liquid ring, and the gas is then extracted under the action of the liquid. Thereby achieving the purpose of vacuuming.