- From: Duff, A. Wilmer, A Text-Book of Physics,
5th ed., P. Blakiston's Son & Co., Philadelphia (1921) pp.
- © Copyright 1998 R. Paselk
- 225. Manometers.
- A manometer is an apparatus for measuring the pressure of a
fluid. In the simplest form the pressure to be measured is balanced
against the pressure of a column of liquid in a tube. This is
called the open tube manometer or siphon gauge. The pressure
is found from the difference of level of the liquid in the two
arms and the density, p, of the liquid. In absolute units
of force P = gph + atmospheric pressure, while in the
weight of unit mass as unit of force P = ph + atmospheric
pressure (Fig. 126).
- In another manometer the pressure to be measured
is balanced against that of a gas (usually air) in a uniform
closed tube. By Boyle's Law the pressure in the gas is inversely
as the volume, that is, inversely as the length of the air column.
The pressure in the gas plus that indicated by the difference
of level of the liquid is the pressure to be measured (Fig. 127).
- © R. Paselk
- Last modified 22 July 2000