Air eliminators are used in liquid systems to aid in the removal of air
and other gases. Many systems designed for liquid service do not operate
well when air is present. One example would be flow metering. Most
flow meters are designed around volumetric measurement principles. Air
passing through a flow meter gets measured just as if it were a liquid, causing
large flow measurement errors. An air eliminator, mounted to the top of a
stilling chamber and installed upstream of the flow meter, will vent this air,
and only liquid will be presented to the flow meter.
Liquid heat transfer systems are another application where air vents are
commonly used. Air will tend to adhere to the tubes in the heat exchanger,
in effect insulating the tubes from the liquid. This will significantly
reduce the amount of heat transfer and can also promote corrosion as the oxygen
in the air provides a key ingredient for oxidation. Again, a properly
installed air eliminator will rid the system of air or other gases, ensuring
superior heat transfer.
Watson McDaniel manufactures air eliminators that sense the density
difference between liquids and gases - the buoyant force acting on a float
actuates the valve plug. Both soft seated and metal seated products are
available.
