TITLE 41: FIRE PROTECTION
CHAPTER I: OFFICE OF THE STATE FIRE MARSHAL
PART 175 TECHNICAL REQUIREMENTS FOR UNDERGROUND STORAGE TANKS AND THE STORAGE, TRANSPORTATION, SALE AND USE OF PETROLEUM AND OTHER REGULATED SUBSTANCES
SECTION 175.440 VENTING OF TANKS
Section 175.440 Venting of Tanks
a) Normal Venting
1) Each tank shall be provided with a separate normal working vent pipe, connected with the top of the tank and carried up to the outer air. Underground manifolding of normal working vents is prohibited. The pipe shall be arranged for proper drainage to the storage tank, and its lower end shall not extend through the top of the tank for a distance of more than one inch; it shall have no traps or pockets. Float vent valve overfill devices are not considered an extension of the standard vent. Manifolded normal vents existing and previously approved by OSFM prior to April 1, 1995 may be left in place, provided that the vents can be shown, by field verification, to comply with OSFM rules at the time of approval.
2) The upper end of the pipe shall be provided with an updraft vent device only, with 40 gauge screening, unless alterations are required by Stage II Vapor Recovery requirements. A pressure vacuum vent will meet this requirement.
3) The vent pipe shall be of sufficient cross-sectional area to permit escape of air and vapor during the filling operation and in compliance with NFPA 30, incorporated by reference in 41 Ill. Adm. Code 174.210, and in no case less than 1¼" in diameter. If a power pump is used in filling the storage tank, and a tight connection is made to the fill pipe, the vent pipe shall not be smaller than the fill pipe.
4) The vent pipe shall terminate outside buildings at a point at least one foot above the level of the highest remote fill or any fill from which the tank may be filled, not less than 12 feet above the adjacent ground level and not less than 5 feet, measured vertically and horizontally, from any window or other building opening, such as a basement, cellar, pit, ventilated soffit or air intake of any building, and in a location that will not permit pocketing of vapor or liquid. The vent piping shall project above any canopy facia no less than 4 feet.
5) No vent piping is allowed inside buildings. Existing vent piping inside buildings may remain if approved, in writing, by OSFM.
6) Adequate collision protection to protect against physical damage shall be provided for vent piping.
7) Hazardous substance tanks shall be vented in accordance with a nationally recognized standard for the substance contained within the tank or as approved by OSFM to be no less protective of human health or the environment.
b) Special Purpose Vents
1) Manifolding of special purpose vents, such as for vapor recovery, is allowed in accordance with NFPA 30.
2) Manifolding of normal working vents aboveground, for the purpose of being tied into a Stage II Recovery System, is allowed providing the following steps are followed:
A) Manifolding will be installed no less than 3 feet above grade and no more than 5 feet aboveground.
B) Each vent shall be capable of being separated and isolated from the manifold.
C) Class II and III products cannot be attached to a manifold that includes Class I products.
D) Final riser shall be of adequate sizing as specified by NFPA 30.