A venturi meter in an oil (sp. gr. 0.8) pipe is connected to a differential manometer in which the gauge liquid is mercury (sp. gr. 13.6). For a flow rate of 0.16 m3/s, the manometer registers a gauge differential of 20 cm. The oil-mercury manometer being unavailable, an air-oil differential manometer is connected to the same venturi meter. Neglecting variation of discharge coefficient for the venturi meter, what is the new gauge differential for a flow rate of 0.08 m3/s?

• A. 64 cm
• B. 68 cm
• C. 80 cm
• D. 85 cm