A toilet diaphragm washer works primarily as a seal to shut off the water supply to the cistern once it has filled to the correct level.
Understanding the Diaphragm Washer's Role
The diaphragm washer is a crucial component, often found within the fill valve (also known as the ballcock or inlet valve) of a toilet cistern. Its main function is to prevent water from continuously flowing into the tank after a flush.
The Mechanism of Action
The process is directly linked to the water level in the cistern and the action of the float:
- Cistern Filling: After a flush, the fill valve opens, allowing water to flow into the cistern.
- Float Rises: As the water level in the cistern increases, a float (which might be a ball or a plastic cup) connected to the fill valve is lifted by the rising water.
- Float Activates Shut-off: The rising float mechanism is designed to interact with the fill valve. According to one reference, "As the cistern fills up the float will be pushed up by the water and will shut off the water coming in by pressing the rubber diaphragm washer."
- Diaphragm Creates Seal: The mechanical linkage from the float presses down on the flexible rubber diaphragm washer inside the valve. This pressure creates a watertight seal against a valve seat, effectively stopping the flow of water into the cistern.
Step-by-Step Water Shut-off
Here's a simplified breakdown of the process:
- Water enters cistern.
- Float rises with water level.
- Rising float mechanism presses on diaphragm washer.
- Diaphragm washer creates a seal.
- Water flow stops.
This mechanism ensures that the cistern fills efficiently and prevents overflow, making the toilet ready for the next flush. The diaphragm washer acts as the final barrier that is activated by the rising water level via the float system.
