Ejectors are pumps without moving parts, driven by pressurized water.

Simplified Explanation:

The ejector pump is based on the fact that a water-jet entrains the surrounding liquid. When this jet is placed incide a duct it can be used to create a substantial vacuum, and with proper design of the duct most of the energy in the mixing jet can be regained as static pressure on the discharge side.

Usage:

Bilge; For all sorts of bilge, e.g. chain lockers, cargo hold bilge and sludge tanks, sewage tanks and other compartments.

Stripping; For stripping of water ballast tanks and cargo oil tanks, and for stripping during cargo tank cleaning.

Vacuum Generation; For evacuating tanks and for priming of centrifugal pumps.

Adventages:

When a motive pump is avaliable the initial and operating cost of ejector are very low. Installation is simple, and since they contain no moving parts reliability is high.

Ejectors may be installed close to the fluid to the pumped, so that long and suction pipes are not needed.

Ejectors have no moving parts and need no maintanance or lubrications.