Two homologous pumps A and B are to run at the same speed. Pump Ahas an impeller diameter of 50 cm and discharge 0.4 m³/s under the head of 50 m. What will be the diameter of pump B, if its discharge is 0.2 m³/s? (Assuming 2^(1/3)= 1.26)

Concept:

Head coefficient

Discharge coefficient

Calculation:

Given:

For Pump A, D_A = 50 cm, Q _A = 0.4 m³/s, H_A = 50 m

For Pump B, Q_B = 0.2 m³/s, D_B = ?

Also, N_A = N_B

We know that

D_B = 39.68 cm

Unit Quantities: (First Preference)

Model Studies: (Second Preference)

Specific Speed: (Third Preference)

 where ‘P’ in kW, ‘N’ in rpm