# How can I calculate the maximum flow rate through a pipe when the velocity is not known?

How I can calculate the maximum mass flow rate through a circular pipe with a inner radius equals 8.5 mm when the velocity is not known? The working fluid is pure water.

## All Answers (12)

Andi Petculescu· University of Louisiana at LafayetteAmin Ebrahimi· Ferdowsi University Of MashhadIn attached image the friction factor versus Reynolds number is presented. Friction factor equation is defined as follow: f=(di/L)*(2Dp/(rho*u^2)) where di is the inner diameter, L is the tube length, Dp is the pressure drop, rho is the fluid density, and u is the mean flow velocity.

Tunç Koray Palazoğlu· Mersin UniversityAmin Ebrahimi· Ferdowsi University Of MashhadMichael Clark· New Mexico State UniversityRajeev Kumar Pundir· Indus International UniversityAbrar Saeed· University of New BrunswickV2/2g = velocity head (from table) then find V

then use G = VA rho G = mass flow rate, v= velocity, rho= density. This flow should be approximately equal to the flow for a pump that will operate at a pressure to maintain the same velocity head that we have calculated above.

Keep in mind velocity heads are calculated based on fluid type (table), pipe dia and roughness. higher flows needs higher diameter and vice versa. we cannot intall a high capacity pump with pipe dia very little. Hence these table helps when velociy is not known to deal with the pump capacity

Juan Francisco Briceño· Universidad Politécnica Antonio José de Sucre, UNEXPOJeremy Goldbloom· Highpower SystemsJuan Francisco Briceño· Universidad Politécnica Antonio José de Sucre, UNEXPOJeremy Goldbloom· Highpower SystemsJuan Francisco Briceño· Universidad Politécnica Antonio José de Sucre, UNEXPOCan you help by adding an answer?