The operation of the pressure-reducing valve is based on the balance between two opposing forces:
1. The thrust of the spring to open the flow passage cross section.
2. The thrust of the diaphragm to close the flow passage cross section.
Operation with water flow
When opening the draw-off outlet, the force of the spring prevails over that of the diaphragm. The obturator moves downwards, thereby opening the valve to the flow of water.
The greater the demand for water, the lower the pressure under the diaphragm. This results in a greater flow of water through the passage cross section.
Operation without water flow
When closing the draw-off outlet, the downstream pressure rises and pushes the diaphragm upwards. This closes off the passage cross-section from the flow of water and keeps the pressure constant at the setting value. The slightest difference in favor of the force exercised by the diaphragm over that of the spring causes the device to close.