When the medium flows into the valve body as indicated by the arrow on the valve body, the pressure of the medium exerts an upward thrust on the valve disc. When the medium thrust exceeds the gravity of the valve disc, the valve opens. When the force exerted by the pressure of the medium behind the valve on the valve disc plus the gravity of the valve disc itself is greater than the force exerted by the pressure before the valve on the valve disc, the valve closes to prevent the medium from flowing back. Suitable for one-way opening and closing on medium pipelines such as water, steam, and petroleum products.
