Ocean-going ships are basically small, stand-alone, self-propelled cities. There are many different types and needs for filtration systems in cities that are on land and the same applies to ships as well. In order to have safe and problem-free operation of filtration systems on ships, proper maintenance is a must. Impurities must be kept from entering various systems by using proper industrial filters and strainers. Additionally, there are various systems onboard ships that use filters, strainers, or both to keep the environment safe and free of contaminants the ship engines can create.
Before we get into the different types of filters and strainers that are used onboard ships, let’s take a look at some of the different filtration systems that must be maintained.
Fuel Systems
Fuel on ships is used to provide propulsive and electrical power. You’ll typically see ships use diesel or heavy fuel oil. Treatment for diesel fuel powered watercraft includes simple water and solid exclusion filtering while heavy fuel oils use a more complex system of settlers, strainers, filters and centrifuges.
Water Systems
Typically, ships have to generate their own water. In the past, this was done by evaporation and the filters were used for saltwater intake. However, reverse osmosis (RO) is seen more and more aboard ships for this process these days. This requires the use of the RO membrane along with pre and post filters and post water treatment to provide fresh water for the vessel.
Filters and Strainers on Ships
A filter is a fine mesh screen that is used to remove impurities from oil, air, and water onboard the ship. A strainer is a type of filter that is used to remove large contamination particles from the system. These two products do have quite a bit in common. They are both used to remove unwanted or contaminated particles from liquids or gasses. They provide similar benefits by protecting equipment that is downstream from impurities. Some filters and strainers are required by regulations or law for safety and environmental reasons.
Differences between Filters and Strainers
The main difference between strainers and filters is the size of the particulates that they are designed to remove. Strainers are designed to remove particulates that are bigger than 40 microns, while filters are designed to remove particulates that are smaller than 40 microns.
Filters in the Fuel System Aboard Ships
The filters that are used in the lube or fuel oil systems on ships fall into the category of hydraulic filters. This type of filter keeps internal parts of machinery from becoming damaged and not functioning properly. Some examples of hydraulic filters are:
- Fine Mesh Screen Filter - This is the most common type of filter used in the ship’s lube and fuel oil systems. It is used in the main engine and auxiliary engine fuel oil line and diesel oil line, cylinder lube oil line, boiler fuel oil line and various other lube oil systems.
- Magnetic Filter - This type of filter has magnetic parts that are useful in attracting and capturing ferrous particles that may be in the system.
- Auto Backwash Filter - With this type of filter, when it begins to clog up, a backflushing process is automatically initiated so the filter cleans itself. The backflushing oil with the sediment from the filter is drained into the fuel oil drain tank from which it can be recovered and purified.
- Centrifugal Filter - These filters work using centrifugal force to remove high density fluids and impurity from the oil system.
Filters in the Water Systems Aboard Ships
- Sea Chest Strainer - The sea chest is an enclosure that is attached to the inside of the underwater shell of the vessel and opens to the sea. It is fitted with a strainer that helps ensure that the flow of water in the line is maintained.
- Fire Line Suction Filter - This type of filter is used in the fire pump to protect the fire line from impurities. It’s very important that water flow in the fire pump is unobstructed so that it can be used to put out any fires on the ship.
- Bilge Line Filter - The bilge well suctions have a strainer because the wells contain solid contamination. The filter may have a bucket screen or a plate screen to trap solid impurities.
Hopefully This Helps
As you can tell, there are many types and applications for filters and strainers on ships. Hopefully, this article helps you understand where filters and strainers are used to ensure ships’ machinery works properly. Check out our cartridge filter product page or strainer product page for more information regarding filter and strainer product options.