Filter is an equipment used for fine separating suspended solid impurities from a fluid on ship.

it is used to filter full oil ( remove oil Impurity of bigger size) lube oil (remove metal particle, unburnt carbon ) bilge water ( remove dirt, rags, cotton waste ) sea water ( remove barnacle,small fish,se a growth) and air line( remove dirt)

it can we simply made up of with a single pair of course gauge, a very course wire mesh or drilled /perforated plate.


it is a filter install to hold/ separate large foreign suspended object to prevent blockage of a fluid system.

It is made up a box with removable lid in which a flat perforated plate is inserted, so that fluid can pass through the perforation on the plate and solid impurities larger than the perforations size get obstructured and remain inside the strainer.

Difference between strainer and filter

1.separate particles of microscopic level finer than 74 Microns.

fitted on pump discharge side .
(small in size compared to strainer)

3.normally used in fuel and lubricating oil lines (AC plates, control ait system)


1. separate particles of macroscopic Level, more than 200 mesh or 74 microns.

2.normally,fitted on pump suction side to protect pump from damage caused by hard solid particles.

3. normally in Bilge lines and bigger in size.

Note :-If the Section condition is critical then external can be fitted on the discharge side.

Types of filter

1.Hydraulic Filter: Hydraulic filters are useful to remove solid contamination from marine equipment lube and fuel oil systems. The inner machine components, bearings, piston, rings, liners, etc. can be harmed without filters in the lube or fuel oil system, resulting in inefficient machine operation. Different hydraulic filter are:

A)Fine mesh screen filter

B)Magnetic filter

C)Auto back wash filter

D)Centrifugal filter

2.Water filter :- On board ship,sea water and fresh water systems are equipped with line filters to trap the system’s strong impurities.

The various water filter applications are:
A)sea chest strainer

B)fire line suction filter

C)Bilge line filter

D)fresh water system filter

3.Air filter :-These filters are used on board to ensure that the compressed air provided to distinct equipment and systems is provided with pure air for effective operation of the same.

The various water filter applications are:

A)control air filter

B)T/c filter

C)compressor filter

D)IG System scrubber filter

4.Special filter :-Some unique filters on board the vessel are as follows:

A)OWS 1st & 2 nd stage filter

B) oxygen analyzer filter

C) cartridge filter