To convert cubic foot per second to gallons per minute, we multiply by 444.8: Multiply the velocity by the cross-sectional area of the pipe:Īrea = 3.14 * (0.20833 / 2) 2 = 0.03409 ft 2 Taking the square root of the above value: Both pitot tubes and static ports are needed in order to derive air speed, as this incident sadly illustrates. It is done so at a separate location, using a static port. Static pressure must be measured, not calculated. Now we multiply the difference in pressure by 2 and divide the result by the density of water ( 62.4 lbs/ft 3). The pitot tube is pointed into the airstream and measures the total pressure. To convert from pounds per square inch to pounds per square foot we will multiply the result by 144: The pressure at the exit point will be equal to the atmospheric pressure, i.e., 14.7 psi.įirst we calculate the difference between the pressure inside the tank ( P 1) and at the exit point ( P 2): Let the pressure inside the tank be 72.0 psi. Let us see how we can calculate the flow rate of water as it exits from a tank through a pipe of diameter 2.5 inches. Step 1: Take a pressure reading at rotor with pitot tube and gauge.
In the next section, we will see how to calculate GPM from pressure. In other words, as the speed of a moving fluid increases, its pressure drops and vice-versa.
P 1 + 1/2 * ρ * v 1 2 = P 2 + 1/2 * ρ * v 2 2 inch schedule 40 pvc plastic pipe is 75 gpm, air from pitot blade and gauge using the bleeder valve the pitot reading in psi and its correlation to the corresponding straight bore discharge data chart will give you the flow in gallons per minute of your apparatus at that rpm after use open bleeder valve to drain pitot tube and gauge this is. (Source: )įor a fluid flowing at a constant depth/height, the above equation changes to: P 1 + 1/2 * ρ * v 1 2 + ρ * g * h 1 = P 2 + 1/2 * ρ * v 2 2 + ρ * g * h 2 A typical geometry used for the derivation of Bernoulli's equation. When the fluid flows through a pipe that has varying diameter and height, the pressure and energy densities at two locations along the pipe are related as: The potential energy density is calculated with the use of a modified potential energy equation, with density instead of mass of the fluid. Bernoulli's equation states that for an incompressible, frictionless fluid, the sum of pressure ( P), kinetic energy density, and potential energy density is constant, i.e.: