Miscellaneous Mechanical Components
Steam traps are installed in steam lines to drain condensate from the lines without
allowing the escape of steam. There are many designs of steam traps for high
and low pressure use.
STATE the purpose and general operation of a steam trap.
IDENTIFY the following types of steam traps:
Ball float steam trap
Bucket steam trap
Bellow steam trap
Impulse steam trap
In general, a steam trap consists of a
Figure 16 Ball Float Steam Trap
valve and a device or arrangement that
causes the valve to open and close as
necessary to drain the condensate from
piping without allowing the escape of
steam. Steam traps are installed at low
points in the system or machinery to be
drained. Some types of steam traps that
are used in DOE facilities are described
in this chapter.
Ball Float Steam Trap
A ball float steam trap is illustrated in
The valve of this trap is
connected to the float in such a way that
the valve opens when the float rises.
When the trap is in operation, the steam
and any water that may be mixed with it
flows into the float chamber. The water,
being heavier than the steam, falls to the bottom of the trap, causing the water level to rise. As
the water level rises, it lifts the float; thus lifting the valve plug and opening the valve. The
condensate drains out and the float moves down to a lower position, closing the valve before the
condensate level gets low enough to allow steam to escape. The condensate that passes out of
the trap is returned to the feed system.