CENTRIFUGAL PUMPS Fluid Flow where: n     =  speed of pump impeller (rpm) =  volumetric flow rate of pump (gpm or ft³/hr) V H_p   =  head developed by pump (psid or feet) p     =  pump power (kW) Using  these  proportionalities,  it  is  possible  to  develop  equations  relating  the  condition  at  one speed to those at a different speed. (3-23) V₁ n₂ n₁ V₂ (3-24) H_p 1 n₂ n₁ 2 H_p 2 (3-25) p₁ n₂ n₁ 3 p₂ Example: Pump Laws A cooling water pump is operating at a speed of 1800 rpm.   Its flow rate is 400 gpm at a head of 48 ft.  The power of the pump is 45 kW.  Determine the pump flow rate, head, and power requirements if the pump speed is increased to 3600 rpm. Solution: Flow rate V₂ V₁ n₂ n₁ (400  gpm) 3600  rpm 1800  rpm 800  gpm HT-03 Page 50 Rev. 0