Page 458 - 2018_IFC

FLAMMABLE AND COMBUSTIBLE LIQUIDS

be stored. Only those liquids tested for compatibility for visual inspection and maintenance of the tank and
with the lining material are allowed to be stored in lined its appurtenances. Dispensing devices are allowed to be
tanks. installed on tops of vaults.
5704.2.8 Vaults. Vaults shall be allowed to be either 5704.2.8.5 Anchoring. Vaults and their tanks shall be
above or below grade and shall comply with Sections suitably anchored to withstand uplifting by ground
5704.2.8.1 through 5704.2.8.18. water or flooding, including when the tank is empty.
5704.2.8.1 Listing required. Vaults shall be listed in 5704.2.8.6 Vehicle impact protection. Vaults shall be
accordance with UL 2245. resistant to damage from the impact of a motor vehicle,
or vehicle impact protection shall be provided in accor-
Exception: Where approved by the fire code offi-
cial, below-grade vaults are allowed to be con- dance with Section 312.
structed on site, provided that the design is in 5704.2.8.7 Arrangement. Tanks shall be listed for
accordance with the International Building Code above-ground use, and each tank shall be in its own
and that special inspections are conducted to verify vault. Compartmentalized tanks shall be allowed and
structural strength and compliance of the installation shall be considered as a single tank. Adjacent vaults
with the approved design in accordance with Sec- shall be allowed to share a common wall. The common
tion 1707 of the International Building Code. Instal- wall shall be liquid and vapor tight and shall be
lation plans for below-grade vaults that are designed to withstand the load imposed when the vault
constructed on site shall be prepared by, and the on either side of the wall is filled with water.
design shall bear the stamp of, a professional engi-
neer. Consideration shall be given to soil and hydro- 5704.2.8.8 Connections. Connections shall be pro-
static loading on the floors, walls and lid; anticipated vided to permit venting of each vault to dilute, disperse
seismic forces; uplifting by groundwater or flood- and remove vapors prior to personnel entering the
ing; and to loads imposed from above such as traffic vault.
and equipment loading on the vault lid. 5704.2.8.9 Ventilation. Vaults that contain tanks of
5704.2.8.2 Design and construction. The vault shall Class I liquids shall be provided with an exhaust venti-
completely enclose each tank. There shall not be open- lation system installed in accordance with Section
ings in the vault enclosure except those necessary for 5004.3. The ventilation system shall operate continu-
access to, inspection of, and filling, emptying and vent- ously or be designed to operate upon activation of the
ing of the tank. The walls and floor of the vault shall be vapor or liquid detection system. The system shall pro-
constructed of reinforced concrete not less than 6 vide ventilation at a rate of not less than 1 cubic foot
inches (152 mm) thick. The top of an above-grade vault per minute (cfm) per square foot of floor area [0.00508
3
3
2
shall be constructed of noncombustible material and m /(s • m )], but not less than 150 cfm (4 m /min). The
shall be designed to be weaker than the walls of the exhaust system shall be designed to provide air move-
vault, to ensure that the thrust of an explosion occurring ment across all parts of the vault floor. Supply and
inside the vault is directed upward before significantly exhaust ducts shall extend to within 3 inches (76 mm),
high pressure can develop within the vault. but not more than 12 inches (305 mm), of the floor. The
exhaust system shall be installed in accordance with the
The top of an at-grade or below-grade vault shall be International Mechanical Code.
designed to relieve safely or contain the force of an
explosion occurring inside the vault. The top and floor 5704.2.8.10 Liquid detection. Vaults shall be
of the vault and the tank foundation shall be designed to equipped with a detection system capable of detecting
withstand the anticipated loading, including loading liquids, including water, and activating an alarm.
from vehicular traffic, where applicable. The walls and 5704.2.8.11 Monitoring and detection. Vaults shall be
floor of a vault installed below grade shall be designed provided with approved vapor and liquid detection sys-
to withstand anticipated soil and hydrostatic loading.
tems and equipped with on-site audible and visual
Vaults shall be designed to be wind and earthquake warning devices with battery backup. Vapor detection
resistant, in accordance with the International Building systems shall sound an alarm when the system detects
Code. vapors that reach or exceed 25 percent of the lower
explosive limit (LEL) of the liquid stored. Vapor detec-
5704.2.8.3 Secondary containment. Vaults shall be
substantially liquid tight and there shall not be backfill tors shall be located not higher than 12 inches (305
around the tank or within the vault. The vault floor mm) above the lowest point in the vault. Liquid detec-
shall drain to a sump. For premanufactured vaults, liq- tion systems shall sound an alarm upon detection of any
uid tightness shall be certified as part of the listing pro- liquid, including water. Liquid detectors shall be
vided by a nationally recognized testing laboratory. For located in accordance with the manufacturer’s instruc-
field-erected vaults, liquid tightness shall be certified in tions. Activation of either vapor or liquid detection sys-
an approved manner. tems shall cause a signal to be sounded at an approved,
constantly attended location within the facility serving
5704.2.8.4 Internal clearance. There shall be suffi- the tanks or at an approved location. Activation of
cient clearance between the tank and the vault to allow vapor detection systems shall shut off dispenser pumps.

2018 INTERNATIONAL FIRE CODE ® 425
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