Steam Basics - What is a Steam Trap?
A steam trap is a device which distinguishes between water and steam and
automatically opens a valve to allow water to pass out but which closes to
steam and traps it.
Traps are of three broad kinds. Those which distinguish water from
steam owing to the difference in density of the two – these are mechanical
types; those which distinguish by means of temperature – these are thermostatic
types; and those which use velocity differences between steam and water – these
are thermodynamic types.
The steam pressures at which steam traps must operate may be anywhere from
vacuum to the highest in practical use.
The quantity of condensate which steam traps have to discharge on different
jobs may vary from a trickle to a flood. They may have to be suitable
for saturated steam or for superheated steam. They may have to discharge
condensate at steam temperature, as soon as it forms in the steam
space: or they may have to discharge it below steam temperature, after it
has given up some of its sensible heat units.
There are about 40 steam trap
manufacturers in the world today, but only few recognize the principles
of operating, and out of the 40 manufacturers, probably ten share the greatest
percentage of total sales volume. It
is, therefore, obvious that many steam trap manufacturers produce the same
type of product with slight design variations that, they claim, have exclusive
advantages over others. The purpose of this website is not to identify
particular manufacturers, but rather, identify the basic operating principles to
help educate the marketplace.