Pitot readings are very small for the common range of air velocities. Ordinary U-tube manometers are not useful for measurement of gas velocities below 12 rn/s. For this,use of inclined tube manometer is suggested. These manometers are well-type with single limb indication. “NMC” Inclined Manometer can be swivelled in 4 positions- 1 in 20, 1 in 10, 1 in 5 & vertical (Approx) Maximum limit of pressure measurement is 250 mm wg.