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 Section 3.
SYSTEM UPGRADE
1 PURPOSE OF SYSTEM UPGRADE. The maintenance of a steam distribution system
m a y occasionally require the installation of additional sections of lines and
traps for system upgrade. D o n o t s a c r i f i c e e f f i c i e n t t r a p p i n g s o l e l y f o r t h e
s a k e of standardization with fewer types, but rather determine the advantages
a g a i n s t easier maintenance and greater longevity.
2 TRAP LIMITATIONS. F e d e r a l Specification WW-T-696 (Latest Revision), Traps,
Steam. and Air, covers a number of commonly used steam traps. The following
l i m i t a t i o n s are provided for consideration when selecting the type of trap to
use.
(a) Bucket trap.
q Trap will not operate where a continuous water seal cannot be
maintained.
q Must
be
protected
from
freezing.
q Air
handling
capacity
not
as
great
as
other
type
traps.
(b) Ball float trap.
q Must
be
protected f r o m freezing.
q Operation of some models may be affected by water hammer.
(c) Disk trap.
q Not
suitable
for
pressures
below
10
psi.
q Not recommended for back pressures greater than 50 percent of
inlet pressure.
q Freeze proof when installed as recommended by manufacturer.
(d) Impulse or orifice trap.
q Not recommended for systems having back pressure greater than 50
p e r c e n t of the inlet pressure.
q Not recommended where subcooling condensate 30F below the
s a t u r a t e d steam pressure is not permitted.
(e) Thermostatic trap.
q Limited to applications where condensate can be held back and
subcooled before being discharged.
q Operation of some models may be affected by water hammer.
q Diaphragm and bellows types are limited to applications of
300 psi and 425F maximum.
8-21
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