Marine eductor is a special water jet pump used for bilge and ballast which doesn’t have a motor and drived by a pressuered working fluid to achieve suction and delivery. As it’s simple structure, maintenance and repair are simple.

Performance Analysis
(1) The influence of the working fluid pressure.
If the other working conditions of the water jet pump remain the same, when the pressure of the working fluid increases, the head ratio decreases, the ejection coefficient increases, and the suction flow increases; conversely, when the working fluid pressure decreases, the head ratio increases and the ejection coefficient decreases. , the suction flow decreases.
(2) The influence of suction pressure.
If the other working conditions of the water jet pump remain the same, when the suction pressure increases, the head ratio decreases, the injection coefficient increases, and the suction flow increases; conversely, when the suction pressure decreases, the head ratio increases, and the injection coefficient decreases , the suction flow decreases.
(3) The influence of the discharge pressure.
If the other working conditions of the jet pump remain the same, when the discharge pressure increases, the head ratio increases, the injection coefficient decreases, and the suction flow decreases; conversely, when the discharge pressure decreases, the head ratio decreases, the injection coefficient increases, and the suction flow decreases.

Maintenance of marine eductor
(1) Features of water jet pump:
① Low efficiency, usually below 25%.
②Small size, simple structure and low price.
③No moving parts, reliable operation, convenient maintenance and long service life.
④ Strong self-priming ability, can create a higher degree of vacuum.
⑤ It can transport any fluid including solid impurities, and it can work normally even if it is submerged in water; water jet pumps are often used exhaust pumps or vacuum pumps for condensing devices and seawater desalination devices, bilge pumps and ballast pumps etc. in ship.
(2) Maintenance of water jet pump:
① Keep the pressure of the working fluid within an appropriate range.
②The discharge stop valve should be fully opened to prevent the discharge pressure from increasing due to discharge check valve jamming or other reasons. It is also necessary to prevent the suction check valve from jamming or reducing the suction pressure due to other reasons.
③The temperature of the working fluid or the ejected fluid should not be too high, otherwise cavitation may occur at the low pressure.
④Keep an appropriate throat-mouth distance.
⑤ Pay attention to check the concentricity of the nozzle, mixing chamber and diffuser. Otherwise, it is easy to increase the hydraulic loss and reduce the efficiency.
⑥Regularly check the condition of the nozzle, and pay attention to prevent corrosion and wear. If the wear is serious, it should be replaced with a new one.