Thoma's cavitation factor Solution

STEP 0: Pre-Calculation Summary
Formula Used
Thoma's Cavitation Factor = (Atmospheric Pressure Head for Pump-Suction head of centrifugal pump-Vapour Pressure Head)/Manometric Head of Centrifugal Pump
σ = (Ha-hs-Hv)/Hm
This formula uses 5 Variables
Variables Used
Thoma's Cavitation Factor - Thoma's Cavitation Factor is used to indicate the onset of cavitation.
Atmospheric Pressure Head for Pump - (Measured in Meter) - The Atmospheric Pressure Head for Pump is the height of a liquid column that corresponds to the atmospheric pressure.
Suction head of centrifugal pump - (Measured in Meter) - Suction head of centrifugal pump is the vertical height of the center line of the pump shaft above the liquid surface in the sump from which the liquid is being raised.
Vapour Pressure Head - (Measured in Meter) - The Vapour Pressure Head is the head corresponding to the vapour pressure of the liquid.
Manometric Head of Centrifugal Pump - (Measured in Meter) - The Manometric Head of Centrifugal Pump is the head against which the centrifugal pump has to work.
STEP 1: Convert Input(s) to Base Unit
Atmospheric Pressure Head for Pump: 28.7 Meter --> 28.7 Meter No Conversion Required
Suction head of centrifugal pump: 7.3 Meter --> 7.3 Meter No Conversion Required
Vapour Pressure Head: 2.2 Meter --> 2.2 Meter No Conversion Required
Manometric Head of Centrifugal Pump: 25.3 Meter --> 25.3 Meter No Conversion Required
STEP 2: Evaluate Formula
Substituting Input Values in Formula
σ = (Ha-hs-Hv)/Hm --> (28.7-7.3-2.2)/25.3
Evaluating ... ...
σ = 0.758893280632411
STEP 3: Convert Result to Output's Unit
0.758893280632411 --> No Conversion Required
FINAL ANSWER
0.758893280632411 0.758893 <-- Thoma's Cavitation Factor
(Calculation completed in 00.020 seconds)

Credits

Created by Sagar S Kulkarni
Dayananda Sagar College of Engineering (DSCE), Bengaluru
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Shri Madhwa Vadiraja Institute of Technology and Management (SMVITM), Udupi
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19 Geometric and Flow Parameters Calculators

Mechanical efficiency given Specific Weight of Liquid
Go Mechanical efficiency of centrifugal pump = (Specific weight of fluid in pump*(Actual discharge at centrifugal pump outlet+Leakage of Liquid from Impeller)*(Velocity of Whirl at Outlet*Tangential Velocity of Impeller at Outlet/[g]))/Input power to centrifugal pump
Overall efficiency
Go Overall efficiency of centrifugal pump = (Specific weight of fluid in pump*Actual discharge at centrifugal pump outlet*Manometric Head of Centrifugal Pump)/Input power to centrifugal pump
Flow velocity at outlet given volume of liquid
Go Flow velocity at outlet of centrifugal pump = Actual discharge at centrifugal pump outlet/(pi*Diameter of centrifugal pump impeller at outlet*Width of Impeller at Outlet)
Volume of liquid at outlet
Go Actual discharge at centrifugal pump outlet = pi*Diameter of centrifugal pump impeller at outlet*Width of Impeller at Outlet*Flow velocity at outlet of centrifugal pump
Flow velocity at inlet given volume of liquid
Go Flow velocity at inlet of centrifugal pump = Actual discharge at centrifugal pump outlet/(pi*Diameter of centrifugal pump impeller at inlet*Width of Impeller at Inlet)
Volume of liquid at inlet
Go Actual discharge at centrifugal pump outlet = pi*Diameter of centrifugal pump impeller at inlet*Width of Impeller at Inlet*Flow velocity at inlet of centrifugal pump
Thoma's cavitation factor
Go Thoma's Cavitation Factor = (Atmospheric Pressure Head for Pump-Suction head of centrifugal pump-Vapour Pressure Head)/Manometric Head of Centrifugal Pump
Leakage of Liquid given Volumetric Efficiency and Discharge
Go Leakage of Liquid from Impeller = (Actual discharge at centrifugal pump outlet/Volumetric efficiency of centrifugal pump)-Actual discharge at centrifugal pump outlet
Torque at outlet
Go Torque at Centrifugal Pump Outlet = (Weight of liquid in pump/[g])*Velocity of Whirl at Outlet*Radius of Impeller at Outlet
Flow velocity given flow ratio
Go Flow velocity at outlet of centrifugal pump = Flow ratio centrifugal pump*sqrt(2*[g]*Manometric Head of Centrifugal Pump)
Flow ratio
Go Flow ratio centrifugal pump = Flow velocity at outlet of centrifugal pump/sqrt(2*[g]*Manometric Head of Centrifugal Pump)
Diameter of delivery pipe
Go Diameter of delivery pipe of pump = sqrt((4*Actual discharge at centrifugal pump outlet)/(pi*Velocity in Delivery Pipe))
Speed ratio
Go Speed ratio centrifugal pump = Tangential Velocity of Impeller at Outlet/sqrt(2*[g]*Manometric Head of Centrifugal Pump)
Diameter of suction pipe
Go Diameter of suction pipe of pump = sqrt((4*Actual discharge at centrifugal pump outlet)/(pi*Velocity in Suction Pipe))
Net positive suction head
Go Net Positive Suction Head of Centrifugal Pump = Atmospheric Pressure Head for Pump-Static Head of Centrifugal Pump-Vapour Pressure Head
Thoma's Cavitation factor given Net Positive Suction Head
Go Thoma's Cavitation Factor = Net Positive Suction Head of Centrifugal Pump/Manometric Head of Centrifugal Pump
Weight of liquid
Go Weight of liquid in pump = Specific Weight of Liquid*Actual discharge at centrifugal pump outlet
Static head
Go Static Head of Centrifugal Pump = Suction head of centrifugal pump+Delivery head of pump
Vane efficiency
Go Vane Efficiency = Actual Head of Pump/Euler Head of Pump

Thoma's cavitation factor Formula

Thoma's Cavitation Factor = (Atmospheric Pressure Head for Pump-Suction head of centrifugal pump-Vapour Pressure Head)/Manometric Head of Centrifugal Pump
σ = (Ha-hs-Hv)/Hm

When does cavitation occur in centrifugal pumps?

Cavitation begins to appear in centrifugal pumps when the pressure at the suction falls below the vapour pressure of the liquid. Thoma’s cavitation factor is used to indicate the onset of cavitation.

How to Calculate Thoma's cavitation factor?

Thoma's cavitation factor calculator uses Thoma's Cavitation Factor = (Atmospheric Pressure Head for Pump-Suction head of centrifugal pump-Vapour Pressure Head)/Manometric Head of Centrifugal Pump to calculate the Thoma's Cavitation Factor, Thoma's cavitation factor formula is defined as the ratio of difference between atmospheric pressure head, suction head, and vapour pressure head to the manometric head. Thoma's Cavitation Factor is denoted by σ symbol.

How to calculate Thoma's cavitation factor using this online calculator? To use this online calculator for Thoma's cavitation factor, enter Atmospheric Pressure Head for Pump (Ha), Suction head of centrifugal pump (hs), Vapour Pressure Head (Hv) & Manometric Head of Centrifugal Pump (Hm) and hit the calculate button. Here is how the Thoma's cavitation factor calculation can be explained with given input values -> 0.758893 = (28.7-7.3-2.2)/25.3.

FAQ

What is Thoma's cavitation factor?
Thoma's cavitation factor formula is defined as the ratio of difference between atmospheric pressure head, suction head, and vapour pressure head to the manometric head and is represented as σ = (Ha-hs-Hv)/Hm or Thoma's Cavitation Factor = (Atmospheric Pressure Head for Pump-Suction head of centrifugal pump-Vapour Pressure Head)/Manometric Head of Centrifugal Pump. The Atmospheric Pressure Head for Pump is the height of a liquid column that corresponds to the atmospheric pressure, Suction head of centrifugal pump is the vertical height of the center line of the pump shaft above the liquid surface in the sump from which the liquid is being raised, The Vapour Pressure Head is the head corresponding to the vapour pressure of the liquid & The Manometric Head of Centrifugal Pump is the head against which the centrifugal pump has to work.
How to calculate Thoma's cavitation factor?
Thoma's cavitation factor formula is defined as the ratio of difference between atmospheric pressure head, suction head, and vapour pressure head to the manometric head is calculated using Thoma's Cavitation Factor = (Atmospheric Pressure Head for Pump-Suction head of centrifugal pump-Vapour Pressure Head)/Manometric Head of Centrifugal Pump. To calculate Thoma's cavitation factor, you need Atmospheric Pressure Head for Pump (Ha), Suction head of centrifugal pump (hs), Vapour Pressure Head (Hv) & Manometric Head of Centrifugal Pump (Hm). With our tool, you need to enter the respective value for Atmospheric Pressure Head for Pump, Suction head of centrifugal pump, Vapour Pressure Head & Manometric Head of Centrifugal Pump and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.
How many ways are there to calculate Thoma's Cavitation Factor?
In this formula, Thoma's Cavitation Factor uses Atmospheric Pressure Head for Pump, Suction head of centrifugal pump, Vapour Pressure Head & Manometric Head of Centrifugal Pump. We can use 1 other way(s) to calculate the same, which is/are as follows -
  • Thoma's Cavitation Factor = Net Positive Suction Head of Centrifugal Pump/Manometric Head of Centrifugal Pump
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