Ventilation
Natural Ventilation
FEDERAL LAW
183.620 - Natural ventilation system
(a) Except for compartments open to the
atmosphere, a natural ventilation system that meets
the requirements of Sec. 183.630
must be provided for each compartment in a boat that:
(3) Contains a permanently installed
fuel tank and an electrical component that is not
ignition protected in accordance with Sec. 183.410(a).
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OPEN TO THE ATMOSPHERE
Compartments that are open to the atmosphere
do not require additional ventilation.
FUEL TANK COMPARTMENTS
A compartment containing a fuel tank that is
permanently installed, as opposed to a portable tank or container,
does not require natural ventilation unless the compartment
contains an electrical component that is not ignition protected.
Ignition protection is defined in Title 33 CFR
Subpart I - Electrical Systems,
183.410(a) as follows:
“(a) Each electrical component must
not ignite a propane gas and air mixture that is 4.25 to
5.25 percent propane gas by volume surrounding the electrical
component when it is operated at each of its manufacturer
rated voltages and current loadings, unless it is isolated
from gasoline fuel sources, such as engines, valves, connections,
or other fittings in vent lines, fill lines, distribution
lines or on fuel tanks, in accordance with paragraph (b)
of this section.”
Another definition is:
“The design and construction of a device
such that under design operating conditions:
- it will not ignite a flammable hydrocarbon
mixture surrounding the device when an ignition source causes
an internal explosion, or
- it is incapable of releasing sufficient
electrical or thermal energy to ignite a hydrocarbon mixture,
or
- the source of ignition is hermetically
sealed.”
"Ignition protected” devices are
not necessarily “explosion proof “or “intrinsically
safe” as those terms are defined by the National Electrical
Code and Title 46 CFR Part 111, sections 105-9 and 105-11.
If, however, a device does meet the definition of either “explosion
proof” or “intrinsically safe”, as referenced
above, then it is also “ignition protected” as
defined in Title 33 CFR Subpart I - Electrical Systems.
Test standards to determine ignition protection
may be found in SAE J1171, External Ignition Protection of
Marine Electrical Devices, and in UL 1500, Ignition Protection
Test for Marine Products.
Usually fuel level senders and the associated
wiring are not sources of ignition and therefore would not
normally require natural ventilation.
TO COMPLY WITH THE LAW
- Does the compartment contain
a permanently installed fuel tank and an electricalcomponent
that is not ignition protected?
If YES, then one of the following must
be answered YES.
- Is the compartment open to the atmosphere
as defined in 183.605, or
- Is natural ventilation provided? See
183.630 for requirement.
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