Question

A venturi meter is 37.5 cm in diameter in mains and 15 cm diameter in throat. The difference between the pressure of water in the mains and the throat is 23 cm of Hg. Find the discharge in litres per minute. Sp.gravity of Hg=13.56

Answer 1

Answer:

The answer will be 8.401.4 lit/min

Explanation:

According to the problem the difference between the pressure in the main and the throat is 23 cm og Hg , The Specific gravity of Hg= 13.56

Therefore the height will be 23 x 13.56 cm water column

Now the diameter of mains is 37.5 cm and throat is of 15 cm

therefore the radius of mains r1= 37.5/2

    and the radius of throat r2= 15/2

Now the cross sectional area of mains , a1= πr1^2  = π(37.5/2)^2

           the cross sectional area of throat , a2= πr2^2 = π(15/2)^2

Now we need to calculate the discharge ,

therefore volume of flow  per minute,

V = a1a2√2gh/√a1^2-a2^2 x 60  cm^2/min

   =  π(37.5/2)^2 x π(15/2)^2 √2 x 980 x  23 x 13.56/√( π(37.5/2)^2)^2- (π(15/2)^2)^2

=  8401.4 litres/min