Consultation on the use of submarine floor drain?

The submarine floor drain uses a valve to control water leakage, that is, when drainage is needed, the valve automatically opens and then closes, only a part of water is reserved in the floor drain to play the role of water seal. There are magnetic direct-acting valves and gravity flap valves. If the sewer has been changed, gravity type is usually used because the depth becomes shallow.

Because of the valve, the water leakage is sometimes intermittent, so there is noise. The plastic in the floor drain has been shrinking, which means you are using magnetic force. When draining water, the valve opens the drain due to the gravity drop of water, and then the valve is attracted, closed and opened by magnetic force, and so on until the water is discharged, that is, gravity is less than magnetic force.