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N N o o t t e e : : To determine the total C C value for a specific
unit, add the appropriate C C values for the
evaporator, standard condenser, and
economizer. If the unit is equipped with any
options (e.g., heat recovery, free cooling, or
an auxiliary condenser), add the applicable C C
value(s) for those options to the total as well.
N N o o t t e e : : The table and figure in
Reference," p. 38
are applicable only for non-
manifolded vent-line runs connected to a 15 psig
(103.4 kPaG) rupture disk relief device. The pipe
length provided by the table is in "equivalent
feet." The vent-line length in equivalent feet is
the sum of the linear pipe length plus the
equivalent length of the fittings (e.g., elbows).
Vent Line Installation
I I m m p p o o r r t t a a n n t t : : Before constructing the rupture disk vent
line, consult local codes for applicable
guidelines and constraints.
All CenTraVac™ centrifugal chillers are equipped with
rupture disks. If refrigerant pressure within the
evaporator exceeds 15 psig (103.4 kPaG), the rupture
disk breaks and shell pressure is relieved as refrigerant
escapes from the chiller.
There are two rupture disks on CDHF chillers, one per
refrigerant circuit. Refer to the following figure (rupture
disk location and cross section) for locations.
A cross-section of the rupture disk assembly appears
inthe following figure (rupture disk location and cross
section), along with an illustration indicating the
location of the rupture disk on the suction elbow.
I I m m p p o o r r t t a a n n t t : : If a RuptureGuard™ is to be installed,
remove and discard the factory-installed
rupture disk; for more information, refer to
Installation, Operation, and Maintenance:
RuptureGuard Pressure Relief System
Option (CTV-SVX06*-EN).
Several general recommendations for rupture disk vent
line installation are outlined as follows.
N N o o t t e e : : If the rupture disk was removed for service or
vent-line piping installation, the rupture disk
must be reinstalled (as shown in the following
figure [rupture disk location and cross section]).
Refer to the following procedure and contact
CenTraVac™ Chiller Technical Service when
reinstalling the rupture disk.
•
Verify that the vacuum support side of the rupture
disk is positioned as shown in the cross-section
view that appears in the following figure (rupture
disk location and cross section).
–
Install the two bottom hex head screws though
the pipe flanges.
–
Install the rupture disk with a gasket on each
side between the pipe flanges. Orient the disk
with the reference arrow or vacuum support bar
CDHF-SVX01N-EN
"Vent Line Sizing
facing the chiller side as shown in the following
figure (rupture disk location and cross section).
–
Install the two top hex head screws.
–
Center the disk and gaskets to the flange bore.
–
Hand-tighten all screws, assuring equal
pressure.
–
Use a torque wrench set to 240 in·lb (27.1 N·m)
with a 9/16-in. socket.
–
Tighten screws in a star pattern, one half turn
each, to maintain even pressure on the disk.
–
Final torque on all screws should be 240 in·lb
(27.1 N·m).
•
When attaching the vent line to the chiller, do NOT
apply threading torque to the outside pipe of the
rupture disk assembly.
N N O O T T I I C C E E
R R u u p p t t u u r r e e D D i i s s k k D D a a m m a a g g e e ! !
F F a a i i l l u u r r e e t t o o f f o o l l l l o o w w i i n n s s t t r r u u c c t t i i o o n n c c o o u u l l d d r r e e s s u u l l t t i i n n
d d a a m m a a g g e e t t o o t t h h e e r r u u p p t t u u r r e e d d i i s s k k a a s s s s e e m m b b l l y y . .
D D o o n n o o t t a a p p p p l l y y t t h h r r e e a a d d i i n n g g t t o o r r q q u u e e t t o o t t h h e e o o u u t t s s i i d d e e p p i i p p e e . .
•
Provide support as needed for the vent line. Do
NOT use the rupture disk assembly to support the
vent-line piping.
•
Use a flexible connection between the vent line and
the rupture disk assembly to avoid placing stress on
the rupture disk. (Stress can alter rupture pressure
and cause the disk to break prematurely.) The
flexible connector used to isolate the rupture disk
from excessive vent line vibration must be
compatible with the refrigerant in use. Use a
flexible, steel connector (such as the stainless-steel
type MFP, style HNE, flexible pump connector from
Vibration Mounting and Control, Inc.), or
equivalent. Refer to the following figure
(arrangement for rupture disk relief piping) for a
recommended relief piping arrangement.
•
An individual vent line is normally installed for each
relief device. It is permissible to manifold the
rupture disks of several machines into a common
vent line provided that the appropriate ASHRAE
Standards and local code requirements for
manifolded relief devices are followed.
N N o o t t e e : : The following figure (arrangement for
rupture disk relief piping) does NOT apply for
manifolded vent lines.
V V e e n n t t P P i i p p i i n n g g
35
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