Diesel Engine has the advantage of high heat efficiency, good economic efficiency and easy to start, so it is easy to suit different kinds of marine and it is used to propel power and supply electricity. In the newly built marine, the diesel engine almost takes place the steam engine totally. The marine diesel engine is the main power of civil ship, middle and small naval vessel and regular vessel.

 Marine diesel engine is usually divided to high speed, middle speed, and low speed diesel engine, Air filter belongs to the air inflow system of the engine, it is made up of one or several filter parts and it is one of the most important parts of the engine

 As the ship is working on the water or sea and the condition is bad, so the air filter that used in on has high rate of damage, which need to be replaced for several months. At present the air filter used now has the following problems, which is summarized from the practice

1.  The housing parts of the Air filter welding uses the spot welding instead of slit bonding. It cannot guarantee the sealing and will cause short out.

2.  The filter, filter element cap, central tube, housing and some other metal parts, without doing rust protection and it cause the metal be rusted and cause impurities, which makes the filter become pollution origin.

3.  The sealing device of the filter upper cover lid cannot be took down, once the sealing ring is aging, the whole filter will be destroyed, which will cause the energy and material waste and it will also cause pollution.