Float flow meter

The flow sensing element of a float flow meter consists of a vertically conical tube that expands from bottom to top, and a float assembly that moves up and down along the axis of the conical tube. As the fluid under test flows from bottom to top through the annular gap 3 formed by cone tube 1 and float 2, a pressure difference is created between the upper and lower ends of the float, generating a force that causes it to rise. When this upward force exceeds the weight of the float submerged in the fluid, the float rises; as a result, the area of the annular gap increases, the flow velocity of the fluid in that gap drops immediately, the pressure difference between the upper and lower ends of the float decreases, and the upward force acting on the float also diminishes. Eventually, when this upward force equals the weight of the float submerged in the fluid, the float stabilizes at a certain height. There is a relationship between the height of the float in the conical tube and the flow rate passing through it.