Vacuum Ejectors: How they Work

Vacuum ejectors, in simple words, work on a principle known as the venturi principle. Venturi principle basically states that you can change the pressure of the liquid or gas by making it travel through a constricted area during its flow/travel time. And this is how this type of vacuum generators work. Yes, this is their basic principle. Now when it comes to their design and actual construction, it just depends on the requirements and their specification as to how much the liquid or air should be constricted to achieve the desired pressure and vacuum.

A typical vacuum ejector will have an input and output area for inserting pressurized air. The input area is usually referred to as the Chest area. Chest area will usually have another opening named as the Suction. This is the area that will output the suction created by the whole machine. The area where the air will discharge/output is commonly known as the Discharge. The Discharge and Chest areas are connected with an area named throat. Throat is the main area and it is used to restrict the flow of the air. Since the Throat’s goal is to restrict the flow of the air, it usually is a bit narrower than the other parts.

Notice how the design is really simple and doesn’t require any mechanical or moving parts. Once the vacuum pump is built, you just have to insert the air from one end and it will simply create the vacuum for you. has written great article about what vacuum ejectors to buy and what not.