U-tube Manometer

Figure 2.11 : U tube Manometer

 

Although the piezometer tube is simple in structure, it has a few practical disadvantages. In this regard U-tube Manometer (Fig. 2.11) seems to be a better alternative. It is a U-tube filled with what is called a gauge fluid. As before one end of the tube is exposed to the pressure to be measured while the other end is open to atmosphere. We have,

$$p_A~+~\gamma_1 h_1~ =~p_2~=~p_3~=~p_{atm}+\gamma_2 h_2$$

$$p_A~ =~\gamma_2 h_2 - \gamma_1 h_1$$ (2.28)

Considerable simplification is possible if the fluid A is a gas when $\rho_1 g h_1$ is negligible, giving

$$p_A~=~\gamma_2 h_2$$

(c) Aerospace, Mechanical & Mechatronic Engg. 2005
University of Sydney