The inlet screen on a fire pump's suction inlet does more than just keep debris from entering the pump. The inlet screen can provide cathodic protection by serving as a sacrificial anode in an effort to reduce galvanic corrosion. Galvanic corrosion occurs when dissimilar metals contact each other. In a fire pump, the dissimilar metals are also affected by the water that is present which electrically connects the metal allowing charged ions to transfer - with one metal becoming the anode (often the pump body) and the other metal the cathode. All of this transferring of ions causes an accelerated corrosion process.

Suction inlet screens that are NOT made of plastic often provide sacrificial anode protection by being coated in zinc. These type of inlet screens will "catch" those bad ions and corrode first, before other more important pump components. Therefore, it is very important to check a pump's suction inlet screens for corrosion and damage and replace them accordingly.

One last note, when installing a suction inlet screen, make sure to clean out any dirt and grease around the contact area of the inlet so that a "good" metal on metal contact is made. All of the major pump manufacturers have maintenance manuals - be sure to read them and follow the recommend inspection and service guidelines.