Question

Difference between orifice and mouthpiece

Answer 1

Actually both orifice and mouthpiece are openings of different types but both are used to measure the discharge of water or liquid.
But the basic difference is that:

Orifice is actually a small opening which may be located at top or bottom or on the sides of tanks. The openings are made such that the discharge of the fluid can be take place.

While the mouthpiece is also the opening, but it is small tube that can be fitted in the tanks according to requirement, this tube is usually projected

Answer 2

An Orifice is a small opening of cross-section that is present on the side at the bottom of the tank.

A mouthpiece is a short length of a pipe which is 2-3 times its diameter in length and is fitted in a tank or vessel that contains the fluid.

In fluid mechanics, both the Orifices and mouthpieces are used for measuring the rate of flow of fluid.