Net Positive Suction Head

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