3. A venturimeter is inserted in a 150 mm diameter pipe carrying an oil of sp. gr. 0-85. If the differential head indicated by the mercury manometer is 0.25 m, and the rate of flow is 80 litres/s, find the diameter of the venturimeter at its throat. Take coefficient for the venturimeter as 0-97.[Ans. 92 mm] In a laboratory, a 100 mm x 50 mm venturimeter was used, which recorded a discharge of 18 litres of water per second, when the mercury reading was 300 mm. What is the value of yenturimeter 4