Section 76.15-5 - Quantity, pipe sizes, and discharge rate(a)General. The amount of carbon dioxide required for each space shall be as determined by the following paragraphs in this section.(b)Total available supply. A separate supply of carbon dioxide need not be provided for each space protected. The total available supply shall be at least sufficient for the space requiring the greatest amount.(c)Cargo spaces.(1) The number of pounds of carbon dioxide required for each space in cubic feet shall be equal to the gross volume of the space in cubic feet divided by 30.(2) Although separate piping shall be led to each cargo hold and 'tween deck, for the purpose of determining the amount of carbon dioxide required, a cargo compartment will be considered as the space between adjacent watertight or firescreen bulkheads and from the tank top or lowest deck to the deck head of the uppermost space on which cargo may be carried. If a trunk extends beyond such deck, the trunk volume shall be included. Tonnage openings shall be considered as sealed for this purpose.(3) Branch lines to the various cargo holds and 'tween decks shall not be less than 3/4 inch standard pipe size.(4) No specific discharge rate need be applied to such systems.(d)Machinery spaces, paint lockers, tanks, and similar spaces.(1) Except as provided in paragraph (d)(3) of this section, the number of pounds of carbon dioxide required for each space shall be equal to the gross volume of the space divided by the appropriate factor noted in table 76.15-5(d)(1). If fuel can drain from the compartment being protected to an adjacent compartment, or if the compartments are not entirely separate, the requirements for both compartments shall be used to determine the amount of carbon dioxide to be provided. The carbon dioxide shall be arranged to discharge into both such compartments simultaneously. Table 76.15-5(d)(1)
| Gross volume of compartment, cubic feet | Factor |
| Over | Not over |
| 500 | 15 |
| 500 | 1,600 | 16 |
| 1,600 | 4,500 | 18 |
| 4,500 | 50,000 | 20 |
| 50,000 | | 22 |
(2) For the purpose of the above requirement of this paragraph, the volume of a machinery space shall be taken as exclusive of the normal machinery casing unless the boiler, internal combustion machinery, or fuel oil installations extend into such space in which case the volume shall be taken to the top of the casing or the next material reduction in casing area, whichever is lower. For installations contracted for on or after October 1, 1959, "normal machinery casing" and "material reduction in casing area" shall be defined as follows:(i) By "normal machinery casing" shall be meant a casing the area of which is not more than 40 percent of the maximum area of the machinery space.(ii) By "material reduction in casing area" shall be meant a reduction to at least 40 percent of the casing area.(3) For vessels on an international voyage contracted for on or after May 26, 1965, the amount of carbon dioxide required for a space containing propulsion boilers or internal combustion propulsion machinery shall be as given by paragraphs (d) (1) and (2) of this section or by dividing the entire volume, including the casing, by a factor of 25, whichever is the larger.(4) Branch lines to the various spaces shall be as noted in table 76.15-5(d)(4). Table 76.15-5(d)(4)
| Maximum quantity of carbon dioxide required, pounds | Minimum nominal pipe size, inches | Maximum quantity of carbon dioxide required, pounds | Minimum nominal pipe size, inches |
| 100 | 1/2 | 2,500 | 21/2 |
| 225 | 3/4 | 4,450 | 3 |
| 300 | 1 | 7,100 | 31/2 |
| 600 | 11/4 | 10,450 | 4 |
| 1,000 | 11/2 | 15,000 | 41/2 |
| 2,450 | 2 | | |
(5) Distribution piping within the space shall be proportioned from the supply line to give proper distribution to the outlets without throttling.(6) The number, type, and location of discharge outlets shall be such as to give a uniform distribution throughout the space.(7) The total area of all discharge outlets shall not exceed 85 percent nor be less than 35 percent of the nominal cylinder outlet area or the area of the supply pipe, whichever is smaller. The nominal cylinder outlet area in square inches shall be determined by multiplying the factor 0.0022 by the number of pounds of carbon dioxide required, except that in no case shall this outlet area be less than 0.110 square inch.(8) The discharge of at least 85 percent of the required amount of carbon dioxide shall be complete within 2 minutes.(e)Spaces specially suitable for vehicles.(1) The number of pounds of carbon dioxide required shall be equal to the gross volume of the largest "tight" space divided by 22. In no case, however, shall it be less than that required by paragraph (c) of this section.(2) The arrangement of valves and piping shall be such that the required quantity of carbon dioxide may be discharged into any "tight" space. The discharge of the required quantity of carbon dioxide shall be completed within 2 minutes.(3) Except as noted in paragraphs (e) (1) and (2) of this section, the requirements of paragraph (d) of this section shall apply.CGFR 65-50, 30 FR 16940, Dec. 30, 1965, as amended by CGFR 66-33, 31 FR 15283, Dec. 6, 1966; CGD 95-028, 62 FR 51204, Sept. 30, 1997; USCG-1999-6216, 64 FR 53225, 53226, Oct. 1, 1999; USCG-2010-0759, 75 FR 60003 , Sept. 29, 2010