the commissioners. No oil-burning system which permits gravity flow of oll to the burner in excess of 1 gallon, which is not equipped with an automatic oil cut-off, shall be used or sold in the District of Columbia. Only oil-burning equipment which has been installed by properly qualified mechanics, has been inspected under the supervision of the District of Columbia fire marshal, and has been approved by him shall be used in the District of Columbia. Where such equipment is used its hazards shall be recognized and the following rules and precautions shall be rigidly observed:

UNDERGROUND STORAGE TANKS

SEO. 2. Storage tanks for fuel oil in excess of 275 gallons shall be located underground. The provisions of Part I, sections 2 to 10, inclusive, shall apply to underground storage tanks installed for domestic use under the provisions of this article.

TANKS INSIDE OF BUILDINGS

SEC. 3. Definition of terms.-The term "supply tank" is used to designate the tank, tanks, or compartment so connected as to permit gravity or pressure flow of fuel oil therefrom to the burner. Gravity or pressure flow shall be employed only when suitable automatic safeguards to prevent abnormal discharge of oil at the burner are provided. The term " storage tank" is used to designate the tank, tanks, or compartment used to store fuel oil in excess of that permitted gravity or pressure flow to the burner.

SEC. 4. Location.-No gravity tank shall be placed within 5 feet, nor any pressure tank within 10 feet, measured horizontally, from any fire or flame. All tanks shall be substantially and rigidly installed on incombustible supports in such manner as to insure protection against mechanical injury. In no case shall the top of the supply tank be placed at a lower level than the top of the storage tank.

SEC. 5. Capacity.—The aggregate capacity of supply and storage tanks located inside of a building and above ground shall not exceed 275 gallons. Oil in excess of 275 gallons shall be placed in underground storage tank or tanks. Gravity or pressure supply from the tank to the burner may be utilized, provided the total capacity of the gravity supply tank shall not

exceed 275 gallons nor the total capacity of pressure supply tank 10 gallons: Provided further, That proper automatic safeguards to prevent abnormal discharge of oil at the burner are provided, and that all such gravity and pressure supply tanks, whether individual storage or combination storage and gravity tank systems, bear the approval of the United States Bureau of Standards or the Underwriters' Laboratories, and that the same be constructed and installed in accordance with the following specifications:

SEO. 6. Tank specifications.-Group 1-Individual tanks:

(a) Size Tanks of this class shall not have capacities exceed 275 United States gallons.

(b) Form-These tanks may be cylindrical or of special forms. Special designs shall require special tests for strength and tightness to determine acceptability.

(c) Material-Open-hearth steel or wrought iron shall be used as material for these tanks.

(d) Thickness-The shell and heads of tanks up to and including 60 United States gallons shall not be less than No. 14 United States standard gage (0.078 inch) in thickness: Provided, That tanks having capacity not in excess of 10 gallons may be constructed of brass, copper, or galvanized-iron plate of not less than No. 18 United States standard gage, except as required for pressure tanks. Tanks of larger than 60 United States gallons capacity shall be made of metal not less than 12 United States standard gage (0.109 inch).

(e) Joints-The joints of these tanks shall be welded, brazed, or riveted and welded.

(f) Pipe connections-Pipe connections shall be made by welding or riveting standard pipe couplings, flanges, or spuds to the tanks. Riveted flanges shall be secured by not less than four rivets on a pitch not to exceed 2 inches. There shall be only one pipe connection provided in or near the bottom of the tank, and at least two in or near the top to permit the necessary supply, overflow, and vent connections. The vent pipe should be of ample size to prevent abnormal pressure in case of fire or when filling, and in no case to be less than 1-inch pipe size. Means shall be provided for removing water and sediment from the bottoms of both gravity and storage tanks. The

threaded portions of pipe connections shall not be less than shown in the following table:

(g) Gauges: Each tank shall be provided with a proper liquid level gauge or equivalent.

(h) Supports: Each tank shall be provided with substantial iron or steel supports. These supports shall be furnished with the tank and shall have provisions for anchoring them to the basement floor. The supports shall not elevate the bottom of the tank more than 4 feet above the floor. They shall be arranged to give maximum stability for the tank in the position in which it is to be used and strong enough to safely support the maximum load to which they may be subjected. The tank shall be firmly anchored to its supports to avoid strains on connecting piping.

(i) Coating: Each tank shall be galvanized or coated outside with a suitable rust-resisting paint.

(j) Test: Each tank, after assembly and before being painted, shall be tested and proven tight against leakage under a test pressure of not less than 5 nor more than 10 pounds per square inch.

(k) Strength: These tanks shall be so designed and constructed that a strength test of 25 pounds per square inch will not rupture them or cause leakage.

(1) Marking: Each tank shall bear the name of the manufacturer.

(m) Shipping: Each tank, before shipping, shall have all pipe-connection openings closed with suitable wood or metal plugs or caps to protect them and keep out foreign matter during shipping.

(n) Systems under pressure: Tanks for systems under preseure shall be designed for six times the maximum working

pressure and shall be tested and proven tight at twice the maximum working pressure; maximum working pressure shall not exceed 50 pounds. Tanks shall be provided with a reliable pressure gauge and an automatic relief valve piped to discharge outside the building. Joints shall be made as specified for underground tanks in section 5 of part 1 of this article.

Group 2.-Combination gravity and storage tanks with pumps: (a) Size: The combined capacity of both gravity and storage tanks shall not exceed 275 United States gallons.

(b) Form: Each tank may be either cylindrical or of special form. Special shapes shall require special tests for strength and tightness to determine acceptability.

(c) Material: Open-hearth steel or wrought iron shall be used as material for these tanks.

(d) Thickness: The shell and heads of tanks not over 60 United States gallons capacity shall not be less than No. 14 United States standard gage (0.078-inch) material. Tanks larger than 60 United States gallons capacity shall be made of metal not lighter than No. 12 United States standard gage (0.109 inch).

(e) Joints: Shall be welded, brazed, or riveted, and welded joints.

(1) Two-compartment tanks: Single combination tanks having gravity and storage sections separated by a compartment head shall have the overflow opening in the head located as near the top as possible and provided with a threaded fitting which can be tightly closed for testing.

(g) Pipe connections: All pipe connections to storage tanks shall be in the top. All connections to gravity tank, except one, the connection for supply to the burner, shall be through or near the top of the gravity tank. Method of attachment and length shall be as specified in paragraph (f) of Group 1. Means shall be provided for removing water and sediment from both the storage and gravity tanks.

(h) Gauges: The storage tank of the combination shall be provided with a proper liquid-level gauge or equivalent, and if a gauge is used on the gravity, it shall be similar to the gauge on the storage tank.

(i) Support and attachment: Supports for storage tank shall be provided as specified for Group 1 tanks. The gravity tank shall be securely attached to the storage tank by substantial metal supports, special attention being given to the load required to be sustained and to the manner in which it is supported. The

supports shall be of ample size and design to safely carry the maximum load sustained.

(j) Pump: A proper hand-operated oil pump or its equivalent shall be provided for transferring oil from storage to gravity tank.

(k) Piping: An overflow pipe shall be provided connecting the gravity tank with the top of the storage tank for returning excess oil pumped. This pipe shall be one pipe size larger than discharge pipe from hand pump. Standard wrought-iron pipe shall be used.

(1) Coating: Each tank shall be galvanized or coated outside with a suitable rust-resisting paint.

(m) Test: After assembly and before painting, each tank shall be tested and proven tight against leakage under a test pressure of not less than 5 nor more than 10 pounds per square inch. Each section of compartment tanks shall be tested as required for separate tanks.

(n) Strength: Each tank shall be so designed and constructed that a strength test of 25 pounds per square inch will not rupture it or cause leakage.

(0) Marking: The manufacturer's name shall appear on at least one tank.

(p) Shipping: Each tank, before shipping, shall have all pipe connection openings closed with suitable wood or metal plugs or caps to protect them and keep out foreign matter during shipment.

(q) Systems under pressure: Tanks for systems under pressure shall be designed for six times the maximum working pressure and shall be tested and proven tight at twice the maximum working pressure; maximum working pressure shall not exceed 50 pounds. Tanks shall be provided with a reliable pressure gauge and an automatic relief valve piped to discharge outside the building. Joints shall be made as specified for underground tanks in section 5 of part 1 of this article.

SEC. 7. Venting of tanks. (a) An independent, permanently open, galvanized-iron vent pipe terminating outside of building shall be provided for every tank. The lower end of the vent pipe shall not extend through the top into the tank for a distance of more than 1 inch.

(b) Vent openings shall be screened (40 by 40 noncorrodible wire mesh or its equivalent, preferably cone shaped), and shall be of sufficient area to permit proper inflow of liquid during the filling operation, and in no case less than 1 inch in diameter.