Installation And Calculating Differential Pressure - Xylem Bell & Gossett Hoffman Speciality Series Engineering Data Manual

Installation
and
Calculating
Differential
Pressure
Trap Installation
Trap draining to gravity return line
EQUIPMENT DRAIN POINT
STATIC
HEAD
SHUT-OFF VALVE
"Y"
STRAINER
DIRT
POCKET
18
Trap Installation
Steam traps should be installed in an acces-
sible location at least 15 inches below the
condensate outlet of equipment or steam
mains being drained. A 15 inch static head at
the trap will provide approximately
ential across the trap when it drains into a
vented gravity return system. During start-up,
before a positive steam pressure is achieved,
the static head is the only differential pres-
sure across the trap. When the steam equip-
ment is controlled by a temperature regulator,
the steam pressure will be reduced as the
valve modulates toward the closed position.
When the pressure drops to O psi, the static
head is the only differential pressure across
the trap. The differential pressure across the
trap can be increased by lowering the trap be-
low the steam equipment. A 2.4 ft. static head
will provide 1 psig. A greater differential pres-
sure will reduce the size of the trap required.
TRAP
TO RETURN LINE
TEST &
PRESSURE
RELIEF
TO DRAIN
GRAVITY RETURN TO
VENTED RECEIVER
Piping Details
A dirt pocket should be provided ahead of the
steam trap to collect scale and dirt. A shut-off
valve should be provided ahead of the trap to
permit service.
1 ⁄
psi differ-
2
Strainers should be provided ahead of the
steam trap to prevent dirt from entering the
trap. Dirt entering the trap can deposit on the
seat and prevent tight closing. A blow-off valve
on the strainer will permit strainer screen
cleaning. Unions or flanges should be provid-
ed to allow removal of the trap for testing,
repair or replacement.
A test and relief valve installed after the trap
permits visual indication of the trap operation,
and assures that internal pressures are
relieved prior to servicing.
A shut-off valve in the trap outlet to the return
line isolates the trap from the return line for
service.
Trap Installation
Trap draining to open drain
STATIC
HEAD
EQUIPMENT DRAIN POINT
SHUT-OFF VALVE
"Y"
STRAINER
DIRT
TO DRAIN
POCKET
TRAP