Dungs FRM-NOC 100025 HD, Instruction Manual, Page: 25 / 76

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MC • Edition 2022.08 • No
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Mounting position
9.3 Vent Lines (Only U.S.A and Canada)
In addition to the requirements below, vent lines shall
be installed in accordance with the applicable instal-
lation code (e.g. NFPA 86, NFPA 37, NFPA 54, B149.3,
B1491) and shall terminate to an approved and safe
location.
Requirements for Vent line Installation
• Keep elbows to an absolute minimum, and when a
90 deg needs to be made, do as follows:
• If using rigid pipe, use long radius elbows (not short).
Long radius elbows have a bending radius of
1.5 times the pipe diameter. Short elbows have a
bending radius of 1 times the pipe diameter.
• If using tubing and permitted by code, use a minimum
bending radius of 2 x the vent line outside diameter.
• Do not reduce along the entire run of the vent line the
pipe size that is established at the regulator’s threaded
vent connection.
• Do not apply a bending moment on the vent line, if rigid
pipe is used. This can apply a large bending force (a se -
vere stress) to the vent connection of the regulator and
damage the housing, which will bypass of the vent line.
• Apply proper pipe hangers and supports so that the vent
line does not load or strain due to the regulator vent line
connection due weight of the vent piping or due to a
bending moment at the vent connection.
Manifolding of vent lines
• Do not manifold the FRM vent with the SAV vent or a
relief valve vent.
• Do not manifold the SAV vent with a relief valve vent.
• Do not manifold other vents of similar devices (regula -
tor to regulator, relief valve to relief valve, etc), unless
permitted by and manifolded in accordance with the
applicable installation code.
Requirements for Vent Line Length and Size for
FRM and SAV vents
• The diameter of vent line shall be the same size at the
vent connection.
• The vent line from the SAV vent connection to the point
of termination shall be the same size.
• The vent line from the FRM vent connection to the point
of termination shall be the same size if
1. downstream equipment is an industrial application
covered by NFPA 37, NFPA 85, NFPA 86, or NFPA
87, or
2. a relief valve (or token relief valve) is mounted down -
stream of the FRM.
Otherwise, the following apply:
• Use schedule 40, 1/2 " pipe or minimum 15mm OD tub -
ing.
• After a length of 15 ft: schedule 40, 3/4 " pipe or minimum
20 mm OD tubing.
• After additional 15 ft, increase pipe to schedule 40,
1 " pipe or minimum 26 mm OD tubing until the point of
termination.
Requirements for the Vent Line’s Point of Termination
• Considerations depending on the gas type:
• For Natural Gas and lighter than air combustible gas -
es, the gas will eventually leave the area of discharge.
• However, for heavier than air combustible or even
non-combustible gases, they could accumulate at the
point of discharge or even accumulate underneath
the point of discharge which can create areas of re -
tained combustible or non-breathable gases. Specific
attention must be taken for such cases.