FROM SEMERATOR
(LEFT END)
MACHINE Sizes 16J8077 THRU IZA
Fig. 3 — Typical Atmospheric (Vented) Condensate Return System
outlet, and trap outlet pressure. A vacuum breaker
is factory installed to ensure that operating steam
pressure in the generator does not fall below
atmospheric pressure. Use the following formulas
to determine available trap pressure drop:
Trap pressure drop = trap inlet ~ trap outlet
psig.
Trap inlet pressure = 0 psig + hydrostatic
head to trap inlet -- condensate leg pressure
drop.
Trap design outlet pressure receiver pres
sure + line pressure drop from trap outlet to
receiver.
In determining trap outlet pressure, discount
any liquid head drop to the receiver. This line may
not run full. If there is liquid lift from trap outlet
to the receiver, it must be added to trap outlet
pressure.
Either float-and-thermostat or inverted-bucket
traps may be used, provided the trap is recom
mended by the manufacturer for rapid handhng of
noncondensables. For fast start-up with inverted-
bucket traps, install an external thermostatic air
vent around the trap.
Traps should be sized for capacity to handle
more condensate than twice the design full-load
steam rate. See steam trap manufacturer’s recom
mendations. Maximum load on the trap will occur
during start-up when generator pressure falls to
atmospheric (0 psig) and steam condenses rapidly.
