Draining Condensate To Overhead Returns - Xylem Bell & Gossett Hoffman Speciality Series Engineering Data Manual

Draining
Condensate to
Overhead
Returns
28
Draining Condensate to Overhead
Returns or into Pressurized Return Lines
When a positive pressure is assured across
the steam trap, 1 psi will raise condensate
2 feet. When a positive pressure is not
assured, such as the case when using a
steam control valve, provision must be made
to drain condensate at reduced pressure
loads and during initial start-up. The use of a
second trap installed at a higher elevation
and connected to a drain may be used as
shown below. The normal trap is connected to
the overhead return line with a check valve to
prevent backflow. The second trap may be a
low pressure trap. When condensate backs
up 4 inches it will drain into the second trap
which will drain condensate into a floor drain
or sump.
When a trap drains into an overhead return
line or pressurized return line, water hammer
may occur due to high temperature conden-
sate flashing as it drains through the trap into
a lower pressure. The check valve after the
trap protects it from the forces created by
water hammer. It also prevents backflow
through the trap when the steam is off.
Draining condensate to overhead return lines
TEMPERATURE
REGULATOR
OVERHEAD RETURN
STEAM LINE
DRIP
TRAP
4" MIN.
TRAP
TRAP
MAX. LIFT
2 FOOT
PER PSI