Minimum speed for starting centrifugal pump Solution

STEP 0: Pre-Calculation Summary
Formula Used
Minimum Speed for Starting Centrifugal Pump = (120*Manometric Efficiency of Centrifugal Pump*Velocity of Whirl at Outlet*Diameter of centrifugal pump impeller at outlet)/(pi*(Diameter of centrifugal pump impeller at outlet^2-Diameter of centrifugal pump impeller at inlet^2))*((2*pi)/60)
Nmin = (120*ηm*Vw2*D2)/(pi*(D2^2-D1^2))*((2*pi)/60)
This formula uses 1 Constants, 5 Variables
Constants Used
pi - Archimedes' constant Value Taken As 3.14159265358979323846264338327950288
Variables Used
Minimum Speed for Starting Centrifugal Pump - (Measured in Revolution per Minute) - Minimum Speed for Starting Centrifugal Pump is the minimum required speed at which the pump impeller should rotate for starting of suction for the pump.
Manometric Efficiency of Centrifugal Pump - Manometric Efficiency of Centrifugal Pump is the ratio of manometric head and head imparted by the impeller.
Velocity of Whirl at Outlet - (Measured in Meter per Second) - The Velocity of Whirl at Outlet is the tangential component of absolute velocity at the blade outlet.
Diameter of centrifugal pump impeller at outlet - (Measured in Meter) - Diameter of centrifugal pump impeller at outlet is the diameter of the impeller at the outlet of the centrifugal pump.
Diameter of centrifugal pump impeller at inlet - (Measured in Meter) - Diameter of centrifugal pump impeller at inlet is the diameter of the impeller at the inlet of the centrifugal pump.
STEP 1: Convert Input(s) to Base Unit
Manometric Efficiency of Centrifugal Pump: 0.82 --> No Conversion Required
Velocity of Whirl at Outlet: 16 Meter per Second --> 16 Meter per Second No Conversion Required
Diameter of centrifugal pump impeller at outlet: 0.28 Meter --> 0.28 Meter No Conversion Required
Diameter of centrifugal pump impeller at inlet: 0.19 Meter --> 0.19 Meter No Conversion Required
STEP 2: Evaluate Formula
Substituting Input Values in Formula
Nmin = (120*ηm*Vw2*D2)/(pi*(D2^2-D1^2))*((2*pi)/60) --> (120*0.82*16*0.28)/(pi*(0.28^2-0.19^2))*((2*pi)/60)
Evaluating ... ...
Nmin = 347.385342789598
STEP 3: Convert Result to Output's Unit
36.3781080272333 Radian per Second --> No Conversion Required
FINAL ANSWER
36.3781080272333 36.37811 Radian per Second <-- Minimum Speed for Starting Centrifugal Pump
(Calculation completed in 00.004 seconds)

Credits

Created by Sagar S Kulkarni
Dayananda Sagar College of Engineering (DSCE), Bengaluru
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Institute of Aeronautical Engineering (IARE), Hyderabad
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15 Pump Parameters Calculators

Minimum speed for starting centrifugal pump
Go Minimum Speed for Starting Centrifugal Pump = (120*Manometric Efficiency of Centrifugal Pump*Velocity of Whirl at Outlet*Diameter of centrifugal pump impeller at outlet)/(pi*(Diameter of centrifugal pump impeller at outlet^2-Diameter of centrifugal pump impeller at inlet^2))*((2*pi)/60)
Work done per second when Flow at Inlet is not Radial
Go Work Done by Pump per Second = (Weight of liquid in pump/[g])*((Velocity of Whirl at Outlet*Tangential Velocity of Impeller at Outlet)-(Velocity of Whirl at Inlet*Tangential Velocity of Impeller at Inlet))
Work done per second per unit weight of liquid if flow at inlet is not radial
Go Work Done by Centrifugal Pump = ((Velocity of Whirl at Outlet*Tangential Velocity of Impeller at Outlet)-(Velocity of Whirl at Inlet*Tangential Velocity of Impeller at Inlet))/[g]
Angular Speed given Specific Speed of Pump
Go Angular velocity of centrifugal pump = (Specific Speed of Centrifugal Pump*(Manometric Head of Centrifugal Pump^(3/4)))/(sqrt(Actual discharge at centrifugal pump outlet))
Specific Speed of Pump
Go Specific Speed of Centrifugal Pump = (Angular velocity of centrifugal pump*sqrt(Actual discharge at centrifugal pump outlet))/(Manometric Head of Centrifugal Pump^(3/4))
Suction specific speed
Go Suction Specific Speed = (Angular velocity of centrifugal pump*sqrt(Actual discharge at centrifugal pump outlet))/((Net Positive Suction Head of Centrifugal Pump)^(3/4))
Head of Pump given Specific Speed
Go Manometric Head of Centrifugal Pump = (Angular velocity of centrifugal pump*sqrt(Actual discharge at centrifugal pump outlet)/Specific Speed of Centrifugal Pump)^(4/3)
Volumetric Efficiency of Pump given Discharge and Leakage of Liquid
Go Volumetric efficiency of centrifugal pump = Actual discharge at centrifugal pump outlet/(Actual discharge at centrifugal pump outlet+Leakage of Liquid from Impeller)
Discharge of pump given specific speed
Go Actual discharge at centrifugal pump outlet = (Specific Speed of Centrifugal Pump*(Manometric Head of Centrifugal Pump^(3/4))/Angular velocity of centrifugal pump)^2
Work done per second for Centrifugal pumps
Go Work Done by Pump per Second = (Weight of liquid in pump/[g])*Velocity of Whirl at Outlet*Tangential Velocity of Impeller at Outlet
Output power
Go Output Power of Centrifugal Pump = (Specific weight of fluid in pump*Actual discharge at centrifugal pump outlet*Manometric Head of Centrifugal Pump)/1000
Static power
Go Static power of centrifugal pump = (Specific weight of fluid in pump*Actual discharge at centrifugal pump outlet*Static Head of Centrifugal Pump)/1000
Work done per second per unit weight of liquid
Go Work Done by Centrifugal Pump = (Velocity of Whirl at Outlet*Tangential Velocity of Impeller at Outlet)/[g]
Work done per second given Torque
Go Work Done by Pump per Second = Torque at Centrifugal Pump Outlet*Angular velocity of centrifugal pump
Angular Velocity of Centrifugal Pump
Go Angular Velocity = (2*pi*Speed of Impeller in RPM)/60

Minimum speed for starting centrifugal pump Formula

Minimum Speed for Starting Centrifugal Pump = (120*Manometric Efficiency of Centrifugal Pump*Velocity of Whirl at Outlet*Diameter of centrifugal pump impeller at outlet)/(pi*(Diameter of centrifugal pump impeller at outlet^2-Diameter of centrifugal pump impeller at inlet^2))*((2*pi)/60)
Nmin = (120*ηm*Vw2*D2)/(pi*(D2^2-D1^2))*((2*pi)/60)

What is the significance of minimum starting speed?

If the pressure rise in the impeller is more than or equal to manometric head (Hm) the centrifugal pump will start delivering water, otherwise, the pump will not discharge any water, though the impeller is rotating. Hence the minimum starting speed is determined.

How to Calculate Minimum speed for starting centrifugal pump?

Minimum speed for starting centrifugal pump calculator uses Minimum Speed for Starting Centrifugal Pump = (120*Manometric Efficiency of Centrifugal Pump*Velocity of Whirl at Outlet*Diameter of centrifugal pump impeller at outlet)/(pi*(Diameter of centrifugal pump impeller at outlet^2-Diameter of centrifugal pump impeller at inlet^2))*((2*pi)/60) to calculate the Minimum Speed for Starting Centrifugal Pump, The Minimum speed for starting centrifugal pump formula is defined as the ratio of product of manometric efficiency, velocity of whirl and diameter of impeller at outlet to the product of pi and difference between the squares of impeller diameter at outlet and inlet. Minimum Speed for Starting Centrifugal Pump is denoted by Nmin symbol.

How to calculate Minimum speed for starting centrifugal pump using this online calculator? To use this online calculator for Minimum speed for starting centrifugal pump, enter Manometric Efficiency of Centrifugal Pump m), Velocity of Whirl at Outlet (Vw2), Diameter of centrifugal pump impeller at outlet (D2) & Diameter of centrifugal pump impeller at inlet (D1) and hit the calculate button. Here is how the Minimum speed for starting centrifugal pump calculation can be explained with given input values -> 36.37811 = (120*0.82*16*0.28)/(pi*(0.28^2-0.19^2))*((2*pi)/60).

FAQ

What is Minimum speed for starting centrifugal pump?
The Minimum speed for starting centrifugal pump formula is defined as the ratio of product of manometric efficiency, velocity of whirl and diameter of impeller at outlet to the product of pi and difference between the squares of impeller diameter at outlet and inlet and is represented as Nmin = (120*ηm*Vw2*D2)/(pi*(D2^2-D1^2))*((2*pi)/60) or Minimum Speed for Starting Centrifugal Pump = (120*Manometric Efficiency of Centrifugal Pump*Velocity of Whirl at Outlet*Diameter of centrifugal pump impeller at outlet)/(pi*(Diameter of centrifugal pump impeller at outlet^2-Diameter of centrifugal pump impeller at inlet^2))*((2*pi)/60). Manometric Efficiency of Centrifugal Pump is the ratio of manometric head and head imparted by the impeller, The Velocity of Whirl at Outlet is the tangential component of absolute velocity at the blade outlet, Diameter of centrifugal pump impeller at outlet is the diameter of the impeller at the outlet of the centrifugal pump & Diameter of centrifugal pump impeller at inlet is the diameter of the impeller at the inlet of the centrifugal pump.
How to calculate Minimum speed for starting centrifugal pump?
The Minimum speed for starting centrifugal pump formula is defined as the ratio of product of manometric efficiency, velocity of whirl and diameter of impeller at outlet to the product of pi and difference between the squares of impeller diameter at outlet and inlet is calculated using Minimum Speed for Starting Centrifugal Pump = (120*Manometric Efficiency of Centrifugal Pump*Velocity of Whirl at Outlet*Diameter of centrifugal pump impeller at outlet)/(pi*(Diameter of centrifugal pump impeller at outlet^2-Diameter of centrifugal pump impeller at inlet^2))*((2*pi)/60). To calculate Minimum speed for starting centrifugal pump, you need Manometric Efficiency of Centrifugal Pump m), Velocity of Whirl at Outlet (Vw2), Diameter of centrifugal pump impeller at outlet (D2) & Diameter of centrifugal pump impeller at inlet (D1). With our tool, you need to enter the respective value for Manometric Efficiency of Centrifugal Pump, Velocity of Whirl at Outlet, Diameter of centrifugal pump impeller at outlet & Diameter of centrifugal pump impeller at inlet and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.
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