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Vents for Underground Flammable Liquid Storage Tanks.
(a) Every underground storage tank containing flammable liquids at atmospheric pressure and having a capacity of more than 100 gallons, shall have a galvanized vent opening so located that the discharge point is outside of any building higher than the fill pipe. Vent pipes from tanks storing Class I, II flammable liquids, and for Class III flammable liquids in tanks containing heaters or hot wells shall be so located that the discharge point is outside of the building, higher than the fill pipe opening, and not less than 12 feet above the adjacent ground level. Vent pipes shall terminate in a weatherproof hood. Vent pipes two inches or less in nominal inside diameter shall not be obstructed by devices that will cause a back pressure exceeding working pressure of the tank, and outlets shall be three feet measured horizontally or vertically from any window or door opening or any other building opening and shall not be trapped under eaves or other obstructions. If the vent pipe is less than ten feet in length or greater than two inches in nominal inside diameter, the outlet shall be provided with an Underwriters' Laboratories, Inc. listed vacuum and pressure-relief device, or there shall be an approved flame arrester located in the vent line at the outlet. In no case shall the flame arrester be located more than 15 feet from the outlet end of the vent line, except any underground gasoline tank installed after the passage of this ordinance shall be piped and equipped for vapor recovery. The vent terminal shall be a minimum of 12 feet or higher above the adjacent ground level and in no case less than three feet higher than the transport truck or tank that will supply such tank. The size of the vent shall be in accordance with paragraph (d) of this section. The outlet shall be provided with an Underwriters' Laboratories, Inc. listed vacuum and pressure-relief device. In no case shall the static head, including the relief device pressure-imposed on the tank, be greater than the working pressure of the tank. The fill pipe shall be of the tight seal type and piped below the suction pipe or pump inlet. No manifolding of vents, syphons, equalizers or other connection to any other tank shall be permitted. Overflow protection shall be provided by piping an extension into the tank to enable the contents of the delivery hose and the vapor recovery hose to flow right back into the storage tank. A dry break adapter and lock-type cap shall be provided with every tank and the recovery hose shall be full sized to the tank truck. No gauging opening shall be permitted, and the fill pipe may be utilized as a gauging opening and shall be kept locked when said tank is not being filled or gauged.
(b) When wire screen is used as a flame arrester, it shall be of noncorrosive wire screen not less than 30 mesh per inch. The screens on such openings shall be at the outer end of vent pipe and so arranged that it can be removed for cleaning purposes.
(c) Where a pump is used with a tight seal fill, the vent shall not terminate on or above any roof.
(d) Vent openings and vent pipes for underground Class I, II and III flammable liquid tanks shall be of ample size to prevent pressure in the tank during filling but not smaller than the pipe size as specified below:
Capacity of Tank U.S.Gallons | Diameter of Vent, Iron Pipe Size (inches) |
500 or less | 1-1/4 |
501 to 3,000 | 1-1/2 |
3,001 to 10,000 | 2 |
10,001 to 20,000 | 2-1/2 |
20,001 to 35,000 | 3 |
35,001 to 50,000 | 4 |
Tanks over 50,000 gallons shall have, in addition to the four-inch vent required for the first 50,000 gallons, an additional vent or vents installed as required by the capacity in the above table.
(Prior code § 129.1-15)
(a) Vent pipes for enclosed storage tanks for fuel oil in connection with oil-burning equipment, and diesel oil in connection with emergency diesel-driven equipment shall be located so that the discharge point is outside of the building, and terminate in a weatherproof hood higher than the fill pipe opening. When such tanks contain heaters or hot wells, the opening of the vent pipe shall not be less than 12 feet above the adjacent ground level. Flame arresters shall be required for two and one-half inch and three inch vent pipes. Where a pump is used with a tight seal fill, the vent shall not terminate on or above any roof.
(b) Vent openings and vent pipes shall be of ample size to prevent pressure in the tank during filling but not smaller than the pipe size as specified below:
Capacity of Tank U.S.Gallons | Diameter of Vent, Iron Pipe Size (inches) |
500 or less | 1-1/4 |
501 to 3,000 | 1-1/2 |
3,001 to 10,000 | 2 |
10,001 to 20,000 | 2-1/2 |
20,001 to 25,000 | 3 |
Vents for Aboveground Flammable Liquid Tanks. Every aboveground flammable liquid tank shall have a vent opening for emergency and normal venting capacity not less than specified in Table 15-24-190(b).
A. Normal venting capacity requirements shall be obtained without exceeding the operating pressure or vacuum which may be applied regularly to a tank without causing physical damage or permanent deformation to the tank.
Inbreathing (vacuum relief) venting capacity requirement for maximum movement out of a tank shall be equivalent to 560 cubic feet of free air per hour for each 4,200 gallons per hour of maximum emptying rate, including gravity flow rate to other tanks, for flammable liquids of any flashpoint. Venting capacity requirement for thermal inbreathing for a given tank capacity for flammable liquids of any flashpoint shall be as shown in Column 2 of Table 15-24-190(a) of this section.
Outbreathing (pressure relief) venting capacity requirement for maximum flammable liquids movement into a tank and resulting evaporation:
(a) Class II and III flammable liquids shall be equivalent to 600 cubic feet of free air per hour for each 4,200 gallons per hour of maximum filling rate.
(b) Class I flammable liquids shall be equivalent to 1,200 cubic feet of free air per hour for each 4,200 gallons per hour of maximum filling rate.
Venting capacity requirement for thermal outbreathing, including thermal evaporation, for a given tank capacity:
(a) Class II and III flammable liquids shall be as shown in Column 3 of Table 15-24-190(a) and in no case shall be less than one and one-fourth inch nominal inside diameter.
(b) Class I flammable liquids shall be as shown in Column 4 of Table 15-24-190(a) and in no case shall be less than one and one-half inch nominal inside diameter. (See Table 15-24-190(a).)
B. Emergency Venting Capacity Requirements. Every aboveground storage tank shall have some form of construction or device that will relieve excessive internal pressure caused by exposure fires, as follows:
In a vertical tank the construction referred to above may take the form of a floating raft, lifter roof, or a weak roof-to-shell seam. The weak roof-to-shell seam (maximum three-sixteenths-inch single fillet weld) shall be constructed to fail preferential to any other seam. Where entire dependence for emergency relief is placed upon pressure-relieving devices, the total venting capacity of both normal and emergency vents shall not be enough to prevent rupture of the shell or bottom of the tank if vertical, or of the shell or heads if horizontal. The total capacity of both normal and emergency venting devices shall not be less than that derived from Table 15-24-190(b). Such device may be a self-closing manhole cover, or one using long bolts that may permit the cover to lift under internal pressure, or a self-closing gauge hatch, or an additional or large relief valve or pressure vacuum valve or valves, or an open vent. The wetted area of the tank shall be calculated on the basis of 55 percent of the total exposed area of a sphere or spheroid, 75 percent of the total exposed area of a horizontal tank and the first 30 feet above grade of the exposed shell area of a vertical tank.
Tank Capacity* | Inbreathing (Vacuum) All Stocks | Outbreathing (Pressure) | |||
(Barrels) | (Gallons) | Flashpoint 100° For Above | Flashpoint Below100°F | ||
Tank Capacity* | Inbreathing (Vacuum) All Stocks | Outbreathing (Pressure) | |||
(Barrels) | (Gallons) | Flashpoint 100° For Above | Flashpoint Below100°F | ||
1 | 2 | 3 | 4 | ||
60 | 2,500 | 60 | 40 | 60 | |
100 | 4,200 | 100 | 60 | 100 | |
500 | 21,000 | 500 | 300 | 500 | |
1,000 | 42,000 | 1,000 | 600 | 1,000 | |
2,000 | 84,000 | 2,000 | 1,200 | 2,000 | |
3,000 | 126,000 | 3,000 | 1,800 | 3,000 | |
4,000 | 168,000 | 4,000 | 2,400 | 4,000 | |
5,000 | 210,000 | 5,000 | 3,000 | 5,000 | |
10,000 | 420,000 | 10,000 | 6,000 | 10,000 | |
15,000 | 630,000 | 15,000 | 9,000 | 15,000 | |
20,000 | 840,000 | 20,000 | 12,000 | 20,000 | |
25,000 | 1,050,000 | 24,000 | 15,000 | 24,000 | |
30,000 | 28,000 | 17,000 | 28,000 | ||
35,000 | 31,000 | 19,000 | 31,000 | ||
40,000 | 34,000 | 21,000 | 34,000 | ||
45,000 | 37,000 | 23,000 | 37,000 | ||
50,000 | 40,000 | 24,000 | 40,000 | ||
60,000 | 44,000 | 27,000 | 44,000 | ||
70,000 | 48,000 | 29,000 | 48,000 | ||
80,000 | 52,000 | 31,000 | 52,000 | ||
90,000 | 56,000 | 34,000 | 56,000 | ||
100,000 | 60,000 | 36,000 | 60,000 | ||
120,000 | 68,000 | 41,000 | 68,000 | ||
140,000 | 75,000 | 45,000 | 75,000 | ||
160,000 | 82,000 | 50,000 | 82,000 | ||
180,000 | 90,000 | 54,000 | 90,000 | ||
* Interpolate for intermediate sizes. | |||||
Wetted Surface, Square Feet (a) | Venting Capacity Cubic Feet Per Hour | Minimum Opening, Iron Pipe Size, Inches (b) |
Wetted Surface, Square Feet (a) | Venting Capacity Cubic Feet Per Hour | Minimum Opening, Iron Pipe Size, Inches (b) |
20 | 21,000 | 2 |
30 | 31,600 | 2 |
40 | 42,100 | 3 |
50 | 52,700 | 3 |
60 | 63,200 | 3 |
70 | 73,700 | 4 |
80 | 84,200 | 4 |
90 | 94,800 | 4 |
100 | 105,000 | 4 |
120 | 126,000 | 6 |
140 | 147,000 | 6 |
160 | 168,000 | 6 |
180 | 190,000 | 6 |
200 | 211,000 | 6 |
250 | 239,000 | 6 |
300 | 265,000 | 6 |
350 | 288,000 | 8 |
400 | 312,000 | 8 |
500 | 354,000 | 8 |
600 | 392,000 | 8 |
700 | 428,000 | 8 |
800 | 462,000 | 8 |
900 | 493,000 | 8 |
1,000 | 524,000 | 10 |
1,200 | 557,000 | 10 |
1,400 | 587,000 | 10 |
1,600 | 614,000 | 10 |
1,800 | 639,000 | 10 |
2,000 | 662,000 | 10 |
2,400 | 704,000 | 10 |
2,800 and over | 742,000 | 10 |
(a) Interpolate for intermediate values.
(b) These pipe sizes apply only to open vent pipes of the indicated diameter not more than 12 inches long and a pressure in tank of not more than 2.5 pounds per square inch. If tank is to be equipped with venting device or flame arrester, the vent opening must accommodate the venting device or flame arrester sized in accordance with Column 2 of Table 15-24-190(b).
(Prior code § 129.1-16)
Gravity Feed Prohibited. No tanks, drums or other containers holding flammable liquids within a building or discharging within a building, shall be provided with any faucet or other bottom-drawing device. Pipes shall not terminate at any point lower than the level of the source of supply. Nothing in this chapter shall be construed as prohibiting the storage or gravity flow or both storage and gravity flow of flammable liquids when such liquids are used in connection with oil-burning equipment installed in accordance with Section 13-180 -160*, or in refineries, or in manufacturing and jobbing plants and in stores, plants, and establishments; provided, however, that tanks holding Class I flammable liquids shall be in a room constructed and arranged as provided by Section 15-24-410 for a special room for flammable liquids.
* Editor's note – Repealed by Coun. J. 7-9-03, p. 3609, § 1.
Fuel oil gravity feed tanks shall not exceed 550 gallons capacity. No gravity supply to a fuel oil-burning appliance shall exceed three psi. Any oil-fired appliance manufactured with a self-contained supply tank shall not be piped to any other source of supply.
(Prior code § 129.1-17)
Notes
| 13-180 | The hyper-linked material is not part of the Chicago Building Code infobase and therefore is not included herein. The material is included in other provisions of the Chicago Municipal Code. The complete Chicago Municipal Code is available for purchase from American Legal Publishing in both print and Folio® versions. Please click here for the appropriate American Legal order form in printable Adobe® PDF format. For additional information, you may visit American Legal's website by clicking here. |
All flammable liquids, except motor fuels, shall be dispensed through gauging or vending devices which shall be of substantial construction and firmly secured to concrete or masonry foundations, which shall be so located and designed as to prevent motor vehicles damaging such systems, except as permitted under Section 15-24-360. Systems wherein continuous pressure is maintained on the flammable liquid storage tank in connection with gauging or vending devices shall not be permitted unless the hazard of the material is such that no other method of dispensing through gauging or vending devices is possible. The use of aboveground flammable liquid storage tanks, or tank cars or tank trucks, in connection with flammable liquid vending or gauging devices, shall not be permitted except as provided in Section 15-24-221. Tank trucks or tank cars shall not be used to store flammable liquids while the liquid is being used.
(Prior code § 129.1-18; Amend Coun. J. 2-16-89, p. 24942; 5-2-95, p. 73)
All flammable liquid gauging, vending and dispensing devices used for motor vehicle fuel shall be of substantial construction, and firmly secured to a concrete foundation, which shall be so located and designed as to prevent motor vehicles from damaging such devices. Systems wherein continuous pressure is maintained, or water is used to displace liquid from storage tanks, shall not be permitted. The use of aboveground storage tanks, tank cars, tank trucks or portable tanks in connection with gauging, vending and dispensing devices, shall not be permitted except for such equipment installed on tank vehicles complying with Section 15-24-1080 and tanks complying with Section 15-24-221 of this Code.
Every remote fuel system shall be equipped with a fuel leak detector valve or device located as close as possible to or within the pumping unit. An impact valve shall be provided at the base of each dispenser. Such devices and valves shall be listed by a testing laboratory which has as its primary purpose the testing and evaluation of equipment and materials to meet appropriate standards.
Automatic hose nozzle valves with latch-open devices shall not be permitted unless equipped with an automatic shut-off device to stop the flow of liquid when the valve is released from a fill opening or upon impact with pavement. All dispensing devices shall be located so that all parts of the vehicles being served will be on private property. In no case shall the dispensing hose be longer than 16 feet for filling stations and private locations. Where dispensing equipment is used exclusively for trucks or other large vehicles, automatic hose retrievers may be used, and shall not exceed 40 feet of hose.
Dispensing devices for motor vehicle fuel, except devices used exclusively for dispensing Class II or Class III flammable liquids within occupancy Class H3 buildings, shall not be permitted in buildings hereafter erected, altered or converted.
The dispensing of motor fuels which are Class I flammable liquids directly from tank vehicles shall be permitted only from tank vehicles complying with Section 15-24-1080 and tanks complying with Section 15-24-221 of this Code. Retail sales of motor fuel to motor vehicles from tank vehicles shall not be permitted. The filling of fuel tanks from tank vehicles shall not be permitted within buildings.
(Prior code § 129.1-18.1; Amend Coun. J. 2-16-89, p. 24942; Amend Coun. J. 10-31-90, p. 22573; Amend Coun. J. 5-2-95, p. 73; Amend Coun. J. 3-19-97, p. 41391)
The use of aboveground storage tanks, tank cars, tank trucks, or portable tanks in connection with vending, gauging, or dispensing of flammable liquids, other than for equipment installed on tank vehicles complying with Section 15-24-1080, shall be permitted only under the following limited circumstances:
(A) The construction and installation of the tanks must satisfy each of the following conditions and restrictions:
(1) Tanks shall be enclosed within a two- hour fire-rated assembly.
(2) The tank assembly shall provide 100 percent secondary containment of the flammable liquid. Dikes as required in Section 15-24-170 need not be provided.
(3) Tanks shall be limited to a capacity of 1,000 gallons.
(4) No more than two such aboveground tanks shall be installed or located at any one site.
(5) The tank shall be completely surrounded by a protective guardrail which is located a minimum of two feet away from the tank.
(6) Dispensing of the flammable liquid shall be by means of a pump which is permanently attached to the top of the enclosing assembly described in subsection (A)(1) above and which is equipped with an anti-syphon valve.
(7) Such tanks shall be located a minimum of ten feet away from any building or property line, except that tanks containing Class II or Class III liquids, as defined in Section 15-24-020, may be located within three feet of a fire-resistive wall without openings.
(8) Each tank shall bear the words, “Flammable – Keep Fire Away”, conspicuously on each side of the tank. The coloring of the letters shall be a color which contrasts with the color of the tank and the letters each must be a minimum of four inches high.
(9) A lockable fill cap shall be provided.
(10) Tanks shall be electrically grounded.
(11) Emergency vents conforming with Section 15-24-190B shall be provided for both the primary tank and the secondary containment space.
(B) Aboveground tanks used pursuant to this section shall not be used for any retail sales.
(Added Coun. J. 5-2-95, p. 73)
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