Product Overview
The process of air formation
The amount of air which can remain dissolved in a water solution is a
function of pressure and temperature. This relationship is governed by
Henry’s law and the graph demonstrates the physical phenomenon of
the air release from water. As an example, at a constant absolute pressure
of 30 psi (2 bar), if the water is heated from 65ºF (18ºC) to 170ºF (75ºC),
the amount of air released by the solution is equal to 1.8 gallons of air
per 100 gallons of water. According to this law it can be seen that the
amount of air released increases with temperature rise and pressure
reduction. The air comes in the form of micro-bubbles of diameters in
the order of tenths of a millmeter.
In heating and cooling systems there are specific points where this process
of formation of micro-bubbles takes place continuously in the boiler and
in any device which operates under conditions of cavitation.
Cavitation and micro-bubbles
Micro-bubbles develop
where the fluid velocity is
very high with the corre-
sponding reduction in pres-
sure. These points are typi-
cally pump impellers and
valve ports.
These air and vapor
micro-bubbles, the
formation of which is
enhanced in the case of non-
deaerated water, may sub-
sequently implode due to
the cavitation phenomenon.
Boiler micro-bubbles
Micro-bubbles are formed
continuously on the surface
separating the water from
the combustion chamber
due to the fluid tempera-
ture. Thisair, carried by the
water, collects in the critical
points of the circuit from
where it must be removed.
Some of this air is reabsorbed
in the presence of colder
surfaces.
Solubility of air in water