Ejector (Eductor) Theory

A Liquid Jet Ejector (Eductor) provides higher discharge pressures and higher suction flow capacities than other standard ejectors.

In operation, pressurized liquid enters the ejector through the pressure nozzle and produces a high-velocity jet. This jet action creates a vacuum in the line which causes the suction liquid to flow up into the body of the ejector where it is entrained by the pressurized liquid.

Both liquids are thoroughly mixed in the throat of the ejector and are discharged against back pressure. The streamlined body permits the pressure liquid to move straight through the ejector and reduces the possibility of solids in the suction material collecting and clogging. In addition, the pressure drop in the suction chamber is held to a minimum.

Ejectors of this type have streamlined investment cast bodies with threaded NPT male pipe connections. PRIMUS steam sterilizers use stainless steel ejectors.


While Liquid Jet Ejectors have no moving parts and are extremely reliable in all types of operating conditions, they are not totally immune to problems and can require periodic inspection and maintenance.

The ejector contains a removable converging nozzle at the inlet of the pressurized water. This nozzle is constructed with 6 small vanes to improve flow through the nozzle. If these vanes become clogged with foreign material, the efficiency of the ejector will be adversely affected.

Simply clean out or remove the foreign material and normal vacuum capability should be restored. In extreme cases, remove the converging nozzle to clean out any debris.

Have a question or having difficulties? Talk to Dave Schall, our PRIMUS sterilizer expert who is here to assist you anytime at 877.679.7800 extension 1212 or email at dschall@spire-is.com.

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