Which pump is used in OWS?

A common type of positive displacement pump in OWS systems is a progressive cavity pump and is also known as an (eccentric) screw pump or even just cavity pump. It transfers fluid by means of the progress, through the pump, of a sequence of small, fixed shape, discrete cavities, as its rotor is turned.

Where are centrifugal pumps used on ship?

They are used on shore for boiler feed applications, irrigation, waste management, as a booster pump, refineries, mining, air conditioning, fire fighting, food production and power generation. These pumps are used on ship’s for bildge, boiler feed, fire fighting, sea water suction and general service pump.

Why positive displacement pumps are preferred to be used on OWS operation?

They are preferred in any application where accurate dosing or high pressure output is required. Unlike centrifugal pumps, the output of a positive displacement pump is not affected by pressure so they also tend to be preferred in any situation where the supply is irregular. Most are self priming.

How do OWS work on ships?

Operating Procedure

1. OWS overboard manual discharge valve is to be kept locked and keys are to be kept with the chief engineer.
2. Open the desired bilge tank valve from which the oily water mixture is to be discharged from OWS.
3. Open air if the control valves are air operated.

What will happen if the operation of OWS fails?

Your vessel may be detained, the owners/operators fined and placed on probation and the involved crew member may be imprisoned and/or fined. Many companies have been fined millions in US Dollars for MARPOL violations worldwide.

What is the difference between centrifugal pump and reciprocating pump?

The main differences between Centrifugal Pump and Reciprocating Pump are the Centrifugal pump works low medium pressure head and Reciprocating Pump works high medium pressure head.

Why centrifugal pump is not a positive displacement pump?

A centrifugal pump is categorised as a non-positive displacement pump. Traps a certain amount of liquid and forces it from the suction to the discharge port. Flow rate remains constant as change in pressure. Standard centrifugal pumps cannot create suction lift.

What are the disadvantages of centrifugal pumps over positive displacement pumps?

Shearing of Liquids The speed of the spinning impeller found within the centrifugal pump design makes it less than ideal for handling shear sensitive mediums. Positive displacement pumps are not designed with any high-speed components, which means these pumps will not apply a great deal of shear to mediums.