VACUUM SYSTEM

A single ejector element is limited at the sometime by the ratio between discharge and suction pressure (dependent from the motive steam pressure and the back pressure) and the maximum load capacity.
Ejectors are utilized in series or in parallel, with or without intermediate condensers, to operate in a very large range of conditions and at lower absolute suction pressures than a single stageunit. The figure below suggests a few of the many type of ejector arrangements that are used in industry.

1.1 Single stage ejector
1.2 3 stage ejector with intercondenser between 2nd and 3rd stage
1.3 3 stage ejector system with intercondensers (3rd stage to the

atmosphere)
1.4 2 stage ejector system with intercondensers (2nd stage to the atmosphere)
1.5 4 stages ejector system (1st stage of non condensing type)
1.6 2 stages ejector system (non condensing type)
1.7 5 stages ejector system (1st and 2nd stages of non condensing type)