The venturi injector's nozzle exit forms a low pressure due to the entrainment effect of high-speed gas flow. The working steam and the suctioned gas mix in the mixing chamber, where energy exchange occurs. The mixed gas is decelerated and pressurized within the diffuser. Depending on the user's vacuum requirement, each steam jet vacuum pump can be configured with a single stage or multiple stages in series. The more stages, the higher the vacuum degree (the lower the residual pressure). The general relationship between the suction pressure and the number of stages is as follows:

To reduce the workload and steam consumption of the first and second-stage ejectors, an intermediate condenser is installed between the first and second-stage ejectors.
To reduce the exhaust noise of the first-stage jet, a silencer condenser is installed after the first-stage jet.
The intermediate condensers and silencer condensers can be divided into direct cooling or indirect cooling types.
Direct-cooled condensers, also known as mixed condensers, are divided into spray and sieve plate types.
Shell and tube condenser, also known as a tubular condenser.