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<br />953• CAPACITY ATID LOCATION OF ABOVE GROUND TANKS.
<br />(a) The location of a tank with respect to distance from tank shell to line
<br />of adjoining property or nearest building shall depend upon the construction, contents,
<br />equipment,'and greatest dimension (diameter, length, er height) of the tank and shall
<br />be in accord~~with the following provisions:
<br />Groups A Tanks. Any all-steel, gas-tight tank constructed in compliance
<br />with these or equivalent standards and equipped either with (1) and approved permanent-
<br />ly attached extinguishing system or (2) an approved floating roof, which is to be used
<br />only for the storage of refined petroleum products or other flammable liquids not
<br />subject to boil over, shall be so located that the distance between shell of tank and
<br />property line or nearest building shall be not less than the greatest dimension
<br />(diameter, length or height) of the tank, except that such distance need not exceed.
<br />I20 feet.
<br />Group B Tanks. Any all-steel, gas-tight tank constructed in comz~liance with
<br />these or equivalent standards but not equipped either with (1) and approved permanently
<br />attached extinguishing system or (2) an approved floating roof,. which is to be used:
<br />only for the storage of refined petroleum products or other flammable liquids not sub-
<br />ject.to boil-over, shall be so located that the distance between shell of tank and
<br />property line or nearest building shall be not less than 12 times the greatest dimension
<br />(diameter, length,=or height) of the tank, except that such distance need not exceed
<br />175 feet.
<br />Group C Tanks. Any all-steel, gas-tight tank constructed in compliance with
<br />these or equivalent standards and equipped either with (1) an approved permanently at-
<br />tached extinguishing system or (2) an approved floating roof, which is to be used for
<br />the storage of crude petroleum or other flammable liquid subject to boil-over, shall be
<br />so located that the distance be~reen shell of tank and property line or nearest build-
<br />ing shall be not less than twice the greatest dimension (diameter, length, or height)
<br />of the tank except that such distance shall be not less than 20 feet ar.d need not exceed
<br />175 feet.
<br />Groups D Tanks. Any all-steel, gas-tight tank constructed in compliance with
<br />these or equivalent standards and not equipped either with (1) and approved permanently
<br />attached extinguishing system or (2) an approved floating roof, which is to be used
<br />for the storage of crude petroleum or other flammable liquid subject to boil-over, shall
<br />be so located that ttie distance between shell .of tank and property line or nearest build-
<br />ing shall be not less than three times the greatest dimension (diameter, length, or
<br />height) of the tank except that such distance shall be not less than 20 feet and need
<br />not exceed 350 feet.
<br />(b)The Minimum distance between shells of any two all-steel, gas-tight tanks
<br />shall be not less than one-half of the greatest dimension (diameter, Length, or height)
<br />of smaller tank except that such distance shall not be less than 3 feet, and for tank
<br />of 18,000 gallons or less the distance need not exceed 3 feet.
<br />EMERGENCY RELIEF OF EXCESSIVE I1ITTERNAL PRESSURES IN ABOVE (MOUND TAi~I~S
<br /> Minimum Approximate diametercf free circular opening (unobstructed by
<br /> Emergency valve discs, etc.) required to discharge petroleum vapors at
<br /> Relief Capa-' the given rates for the following allowable internal pressures.
<br />Capacity city Required
<br />of Tank Cubic Feet Per 3 inches 1 Lb. per 25 Lbs per
<br />Gallons Hour. of water Sq. In. 5 Lbs,, per
<br /> Sq. in.
<br /> (Based upon an orifice coefficient of 0.7 and
<br /> vapor specific gravity of 2.5.)
<br />1, 000 16, 000 1.4" 2g ~ ` ~ 11" 1"
<br />!~, o00 1.~, o00 6 ~/~." 3 3/~" ~" 1 3/~+"
<br />18, o00 88, 004 9?"
<br />~ 52" 3 3/~+" ~"
<br />25,000 105,000 10~
<br />-" 6" "
<br />~+ "
<br />2 3/4
<br />56,000 160,000 ~ 12 3/~+" 74" a 5" 34"
<br />1a4, 400 230, o00 15'~"
<br />~ s 3/!~"
<br />~ 6" 1~"
<br />155,000 290,000 17
<br />m 9 3/~+" ~" ~"
<br />222, 000 330, 004 = . 18~" 10~" 7" ~ 3/1~"
<br />475, 000 395, 000 = 20" 111tt 7 3/fit" 5" -
<br />735,000
<br />li
<br />it
<br />U
<br />d t~lo,oo0
<br />x
<br />10
<br />000 20~"
<br />20
<br />" zl~'f
<br />ll
<br />" 7 3/~+"
<br />!
<br />" 5~",
<br />"
<br />n
<br />e
<br />m .
<br />, ~ ti 7 3/
<br />a. 5~
<br />956. MATERIAL OF URTDERGROUND TANKS.
<br />Tanks shall be constructed of galvanized steel, open hearth_steel or wrought iron
<br />of a thickness not less than specified in Table 3. For liquids heavier than 35° A.P.I.
<br />tanks may be constructed of concrete in acccrdanee with the Standards of the National
<br />Board of Fire Underwriters.
<br />
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