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4. Support the vent piping, use a
flexible connection to avoid
placing stress on the rupture disc.
(Stress can alter rupture pressure
and cause the disc to break
prematurely.)
The flexible connector used to
isolate the rupture disc 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.
Table 8 - "C" Value Used to Determine Rupture Disc Vent Line Size CDHF & CDHG
Evaporator
NTON
Shell
Compressor
Size
Size
EVSZ
1250-2000
210D
1250-2150
210D
2100-2500
250D
3000
250M
3500
250X
Notes:
1. Use the Total "C" Value for Each Circuit to determine the vent line diameter needed to handle the flow, refer to
Figure 21.
2. If piping multiple rupture discs to a common vent line, first determine the total "C" value for each rupture disc, then
add all "C" values together and apply the result to the "Vent Pipe Sizing Chart" Figure 21.
3. EVSZ = Evaporator Shell Size
D = Duplex
4. CDSZ = Condenser Shell Size
D = Duplex
36
Vent Line Piping
See Figure 20C for a recommended
relief piping arrangement.
Important! Vent pipe size must
conform to ANSI/ASHRAE Standard
15, which discusses vent pipe sizing.
Use Table 8 and then Figure 21 to
determine proper vent pipe size.
Note: To determine the total "C"
value for a specific unit, add the
appropriate "C" values for the
evaporator, condenser and
economizer. With this sum, refer to
Figure 21 to determine the vent line
pipe diameter needed to handle
flow.
Condenser
Shell
Rupture
Size
Disc
CDSZ
Diameter
210D
3"
210D
3"
250D
3"
250M
3"
250X
3"
5. If the two vent lines are piped
together, size the common line
appropriately to handle the total
flow. (See Note 2, Table 8).
6. Normally, where multiple chillers
are used, install a separate rupture
disc vent line for each unit.
7. Consult local regulations for any
special relief line requirements
and refer to CFC-GUIDE-2
published by The Trane Company.
8. The discharge of the vent line
outside should not be in the
general vicinity of any fresh air
intakes to the building. Any gas
venting from the vent line should
not be allowed to re-enter the
building.
"C" Value for Each Component for
Each Duplex Side
Evaporator Condenser
53.6
40.4
53.6
40.4
59.1
43.9
72.2
53.8
83.3
62.0
Total
"C" Value for
Each Duplex
Economizer
Side
17.4
111.4
17.4
111.4
17.4
120.4
19.5
145.5
19.5
164.8
CDHF-SVN01B-EN
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