I have three rectangular diesel tanks. The three vents use a single, three
into one T so there is only one actual vent.
I know I need to re-do it as the T is below the level of the fuel fill. Fuel
entering tank A begins to fill tank B and C.
Does anyone have this part of the rules as I need to know if I will need 1
or 3 vents when I re-do it all.

On Oct 12, 5:36*pm, "Jimjamie" wrote:
I have three rectangular diesel tanks. The three vents use a single, three
into one T so there is only one actual vent.
I know I need to re-do it as the T is below the level of the fuel fill. Fuel
entering tank A begins to fill tank B and C.
Does anyone have this part of the rules as I need to know if I will need 1
or 3 vents when I re-do it all.

33.13 TANK VENT SYSTEMS
33.13.1 The fuel vent system shall be designed to prevent
spilling liquid fuel into the boat, or the environment, when
tested in accordance with H-33.17.4 while fueling the boat
in accordance with the boat manufacturer's instructions.
33.13.2 Minimum inside diameter of vent line shall be
7/16 inch (11.11mm).
33.13.2.1 The minimum inside diameter of vent
openings in the fuel tank shall be 5/16 inch (7.93mm).
33.13.3 Each vent shall have a flame arrester that can be
cleaned, unless the vent system is itself a flame arrester.
NOTE: Vent fittings that are removable are considered
cleanable.
33.13.4 Fuel vent lines shall be metallic or hose.
33.13.4.1 Flexible fuel vent hose, if used, shall comply
with H-33.6.
33.13.5 Separation between compartment ventilation
openings and fuel tank vent line terminations shall be at
least 15 inches (381mm).
33.13.6 The tank vent pipe shall have provision to
minimize the intake of water without restricting the
continuous release of vapor.
33.13.7 The vent system shall be self draining, and
33.13.7.1 shall connect to the highest point of the fuel
tank as installed in the boat under conditions of normal
operation and normal trim.
NOTES:
1. In sailing auxiliaries, it may be necessary to have dual
vents, each equal in size to the specification in H-33.13.2.
2. This does not require separate lines from the tank for
vent and fill systems.
33.13.7.2 All fittings and connections of the tank vent
system shall be readily accessible, or accessible through an
access panel, port or hatch.

Peter Eikenberry
newboatbuilders.com

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