### U.S. Code of Federal Regulations

Regulations most recently checked for updates: Feb 17, 2020

(a) *Detailed filling requirements.* Liquefied gases (except gas in solution) must be offered for transportation, subject to the requirements in this section and §§ 173.301 and 173.304, in specification cylinders, as follows:

(1) DOT 3, 3A, 3AA, 3AL, 3B, 3BN, 3E, 4B, 4BA, 4B240ET, 4BW, 4E, 39, except that no DOT 4E or 39 packaging may be filled and shipped with a mixture containing a pyrophoric liquid, carbon bisulfide (disulfide), ethyl chloride, ethylene oxide, nickel carbonyl, spirits of nitroglycerin, or toxic material (Division 6.1 or 2.3), unless specifically authorized in this part.

(2) For the gases named, the following requirements apply (for cryogenic liquids, see § 173.316):

Kind of gas | Maximum permitted filling density (percent)
(see Note 1) | Packaging marked as shown in this column or of the same type with higher service pressure must be used, except as provided in §§ 173.301(l), 173.301a(e), and 180.205(a)
(see notes following table) |
---|---|---|

Anhydrous ammonia | 54 | DOT-3A480; DOT-3AA480; DOT-3A480X; DOT-4AA480; DOT-3; DOT-3E1800; DOT-3AL480. |

Bromotrifluoromethane (R-13B1 or H-1301) | 124 | DOT-3A400; DOT-3AA400; DOT-3B400; DOT-4AA480; DOT-4B400; DOT-4BA400; DOT-4BW400; DOT-3E1800; DOT-39; DOT-3AL400. |

Carbon dioxide ( | 68 | DOT-3A1800; DOT-3AX1800; DOT-3AA1800; DOT-3AAX1800; DOT-3; DOT-3E1800; DOT-3T1800; DOT-3HT2000; DOT-39; DOT-3AL1800. |

Carbon dioxide (see Notes 4, 7, and 8) | 70.3 | DOT-3A2000, DOT-3AA2000, DOT-3AX2000, DOT-3AAX2000, DOT-3T2000. |

Carbon dioxide (see Notes 4, 7, and 8) | 73.2 | DOT-3A2265, DOT-3AA2265, DOT-3AX2265, DOT-3AAX2265, DOT-3T2265. |

Carbon dioxide (see Notes 4, 7, and 8) | 74.5 | DOT-3A2400, DOT-3AA2400, DOT-3AX2400, DOT-3AAX2400, DOT-3T2400. |

Carbon dioxide, refrigerated liquid ( | DOT-4L. | |

Chlorine ( | 125 | DOT-3A480; DOT-3AA480; DOT-3; DOT-3BN480; DOT-3E1800. |

Chlorodifluroethane or 1-Chloro-1, 1-difluoroethane (R-142b) | 100 | DOT-3A150; DOT-3AA150; DOT-3B150; DOT-4B150; DOT-4BA225; DOT-4BW225; DOT-3E1800; DOT-39; DOT-3AL150. |

Chlorodifluoromethane (R-22) ( | 105 | DOT-3A240; DOT-3AA240; DOT-3B240; DOT-4B240; DOT-4BA240; DOT-4BW240; DOT-4B240ET; DOT-4E240; DOT-39; DOT-3E1800; DOT-3AL240. |

Chloropentafluorethane (R-115) | 110 | DOT-3A225; DOT-3AA225; DOT-3B225; DOT-4BA225; DOT-4B225; DOT-4BW225; DOT-3E1800; DOT-39; DOT-3AL225. |

Chlorotrifluoromethane (R-13) ( | 100 | DOT-3A1800; DOT-3AA1800; DOT-3; DOT-3E1800; DOT-39; DOT-3AL1800. |

Cyclopropane ( | 55 | DOT-3A225; DOT-3A480X; DOT-3AA225; DOT-3B225; DOT-4AA480; DOT4B225; DOT-4BA225; DOT-4BW225; DOT-4B240ET; DOT-3; DOT-3E1800; DOT-39; DOT-3AL225. |

Dichlorodifluoromethane (R-12) ( | 119 | DOT-3A225; DOT-3AA225; DOT-3B225; DOT-4B225; DOT-4BA225; DOT-4BW225; DOT-4B240ET; DOT-4E225; DOT-39; DOT-3E1800; DOT-3AL225. |

Dichlorodifluoromethane and difluoroethane mixture (constant boiling mixture) (R-500) ( | Not liquid full at 131 °F | DOT-3A240; DOT-3AA240; DOT-3B240; DOT-3E1800; DOT-4B240; DOT-4BA240; DOT-4BW240; DOT-4E240; DOT-39. |

1,1-Difluoroethane (R-152a) ( | 79 | DOT-3A150; DOT-3AA150; DOT-3B150; DOT-4B150; DOT-4BA225; DOT-4BW225; DOT-3E1800; DOT-3AL150. |

1,1-Difluoroethylene (R-1132A) | 73 | DOT-3A2200; DOT-3AA2200; DOT-3AX2200; DOT-3AAX2200; DOT-3T2200; DOT-39. |

Dimethylamine, anhydrous | 59 | DOT-3A150; DOT-3AA150; DOT-3B150; DOT-4B150; DOT-4BA225; DOT-4BW225; ICC-3E1800. |

Ethane ( | 35.8 | DOT-3A1800; DOT-3AX1800; DOT-3AA1800; DOT-3AAX1800; DOT-3; DOT-3E1800; DOT-3T1800; DOT-39; DOT-3AL1800. |

Ethane ( | 36.8 | DOT-3A2000; DOT-3AX2000; DOT-3AA2000; DOT-3AAX2000; DOT-3T2000; DOT-39; DOT-3AL2000. |

Ethylene ( | 31.0 | DOT-3A1800; DOT-3AX1800; DOT-3AA1800; DOT-3AAX1800; DOT-3; DOT-3E1800; DOT-3T1800; DOT-39; DOT-3AL1800. |

Ethylene ( | 32.5 | DOT-3A2000; DOT-3AX2000; DOT-3AA2000; DOT-3AAX2000; DOT-3T2000; DOT-39; DOT-3AL2000. |

Ethylene ( | 35.5 | DOT-3A2400; DOT-3AX2400; DOT-3AA2400; DOT-3AAX2400; DOT-3T2400; DOT-39; DOT-3AL2400. |

Hydrogen chloride, anhydrous | 65 | DOT-3A1800; DOT-3AA1800; DOT-3AX1800; DOT-3AAX1800; DOT-3; DOT-3T1800; DOT-3E1800. |

Hydrogen sulfide ( | 62.5 | DOT-3A; DOT-3AA; DOT-3B; DOT-4A; DOT-4B; DOT-4BA; DOT-4BW; DOT-3E1800; DOT-3AL. |

Insecticide, gases liquefied ( | Not liquid full at 131 °F | DOT-3A300; DOT-3AA300; DOT-3B300; DOT-4B300; DOT-4BA300; DOT-4BW300; DOT-3E1800. |

Liquefied nonflammable gases, other than classified flammable, corrosive, toxic & mixtures or solution thereof filled w/nitrogen, carbon dioxide, or air ( | Not liquid full at 131 °F | Specification packaging authorized in paragraph (a)(1) of this section and DOT-3HT; DOT 4D; DOT-4DA; DOT-4DS. |

Methyl acetylene-propadiene, mixtures, stabilized; ( | Not liquid at 131 °F | DOT-4B240 without brazed seams; DOT-4BA240 without brazed seams; DOT-3A240; DOT-3AA240; DOT-3B240; DOT-3E1800; DOT-4BW240; DOT-4E240; DOT-4B240ET; DOT-3AL240. |

Methyl chloride | 84 | DOT-3A225; DOT-3AA225; DOT-3B225; DOT-4B225; DOT-4BA225; DOT-4BW225; DOT-3; DOT-3E1800; DOT-4B240ET. Cylinders complying with DOT-3A150; DOT-3B150; and DOT-4B150 manufactured prior to Dec. 7, 1936 are also authorized. |

Methyl mercaptan | 80 | DOT-3A240; DOT-3AA240; DOT-3B240; OT-4B240; DOT-4B240ET; DOT-3E1800; DOT-4BA240; DOT-4BW240. |

Nitrosyl chloride | 110 | DOT-3BN400 only. |

Nitrous oxide ( | 68 | DOT-3A1800; DOT-3AX1800; DOT-3AA1800; DOT-3AAX1800; DOT-3; DOT-3E1800; DOT-3T1800; DOT-3HT2000; DOT-39; DOT- 3AL1800. |

Nitrous oxide ( | 70.3 | DOT-3A2000, DOT-3AA2000, DOT-3AX2000, DOT-3AAX2000, DOT-3T2000. |

Nitrous oxide ( | 73.2 | DOT-3A2265, DOT-3AA2265, DOT-3AX2265, DOT-3AAX2265, DOT-3T2265. |

Nitrous oxide ( | 74.5 | DOT-3A2400, DOT-3AA2400, DOT-3AX2400, DOT-3AAX2400, DOT-3T2400. |

Nitrous oxide, refrigerated liquid ( | DOT-4L. | |

Refrigerant gas, n.o.s. or Dispersant gas, n.o.s. ( | Not liquid full at 130 °F | DOT-3A240; DOT-3AA240; DOT-3B240; DOT-3E1800; DOT-4B240; DOT-4BA240; DOT-4BW240; DOT-4E240; DOT-39; DOT-3AL240. |

Sulfur dioxide ( | 125 | DOT-3A225; DOT-3AA225; DOT-3B225; DOT-4B225; DOT-4BA225; DOT-4BW225; DOT-4B240ET; DOT-3; DOT-39; DOT-3E1800; DOT-3AL225. |

Sulfur hexafluoride | 120 | DOT-3A1000; DOT-3AA1000; DOT-AAX2400; DOT-3; DOT-3AL1000; DOT-3E1800; DOT-3T1800. |

Sulfuryl fluoride | 106 | DOT-3A480; DOT-3AA480; DOT-3E1800; DOT-4B480; DOT-4BA480; DOT-4BW480. |

Tetrafluoroethylene, stabilized | 90 | DOT-3A1200; DOT-3AA1200; DOT-3E1800. |

Trifluorochloroethylene, stabilized | 115 | DOT-3A300; DOT-3AA300; DOT-3B300; DOT-4B300; DOT-4BA300; DOT-4BW300; DOT-3E1800. |

Trimethylamine, anhydrous | 57 | DOT-3A150; DOT-3AA150; DOT-3B150; DOT-4B150; DOT-4BA225; DOT-4BW225; DOT-3E1800. |

Vinyl chloride ( | 84 | DOT-4B150 without brazed seams; DOT-4BA225 without brazed seams; DOT-4BW225; DOT-3A150; DOT-3AA150; DOT-3E1800; DOT-3AL150. |

Vinyl fluoride, stabilized | 62 | DOT-3A1800; DOT-3AA1800; DOT-3E1800; DOT-3AL1800. |

Vinyl methyl ether, stabilized( | 68 | DOT-4B150, without brazed seams; DOT-4BA225 without brazed seams; DOT-4BW225; DOT-3A150; DOT-3AA150; DOT-3B1800; DOT-3E1800. |

^{3} at 60 °F.).

(b) [Reserved]

(c) *Verification of content in cylinder.* Except as noted in paragraph (d)(4) of this section, the amount of liquefied gas filled into a cylinder must be by weight or, when the gas is lower in pressure than required for liquefaction, a pressure-temperature chart for the specific gas may be used to ensure that the service pressure at 55 °C (131 °F) will not exceed

(d) Requirements for liquefied petroleum gas. (1) Filling density limits are as follows:

Minimum specific gravity of liquid material at 60 °F | Maximum the filling density in percent of the water-weight capacity of the cylinder |
---|---|

0.271 to 0.289 | 26 |

0.290 to 0.306 | 27 |

0.307 to 0.322 | 28 |

0.323 to 0.338 | 29 |

0.339 to 0.354 | 30 |

0.355 to 0.371 | 31 |

0.372 to 0.398 | 32 |

0.399 to 0.425 | 33 |

0.426 to 0.440 | 34 |

0.441 to 0.452 | 35 |

0.453 to 0.462 | 36 |

0.463 to 0.472 | 37 |

0.473 to 0.480 | 38 |

0.481 to 0.488 | 39 |

0.489 to 0.495 | 40 |

0.496 to 0.503 | 41 |

0.504 to 0.510 | 42 |

0.511 to 0.519 | 43 |

0.520 to 0.527 | 44 |

0.528 to 0.536 | 45 |

0.537 to 0.544 | 46 |

0.545 to 0.552 | 47 |

0.553 to 0.560 | 48 |

0.561 to 0.568 | 49 |

0.569 to 0.576 | 50 |

0.577 to 0.584 | 51 |

0.585 to 0.592 | 52 |

0.593 to 0.600 | 53 |

0.601 to 0.608 | 54 |

0.609 to 0.617 | 55 |

0.618 to 0.626 | 56 |

0.627 to 0.634 | 57 |

(2) Subject to § 173.301a(d), any filling density percentage prescribed in this section is authorized to be increased by a factor of 2 for liquefied petroleum gas in DOT 3 cylinders or in DOT 3A cylinders marked for 1800 psig, or higher, service pressure.

(3) Liquefied petroleum gas must be shipped in specification cylinders as follows:

(i) DOT 3, 3A, 3AA, 3B, 3E, 3AL, 4B, 4BA, 4B240ET, 4BW, 4E, or 39 cylinders. Shipments of flammable gases in DOT 3AL cylinders are authorized only when transported by motor vehicle, rail car, or cargo-only aircraft.

(ii) Additional containers may be used within the limits of quantity and pressure as follows:

Type of container | Maximum capacity (cubic inches) | Maximum filling pressure
(psig) |
---|---|---|

DOT-2P or DOT-2Q (see Note 1) | 31.83 | 45 psig at 70 °F and 105 psig at 130 °F (see Note 2). |

DOT-2P or DOT-2Q (see Note 1) | 31.83 | 35 psig at 70 °F and 100 psig at 130 °F. |

(4) *Verification of content.* A cylinder with a water capacity of 90.72 kg (200 lb) or more and for use with a liquefied petroleum gas with a specific gravity of 0.504 or greater at 16 °C (60 °F) may have the quantity of its contents determined by using a fixed length dip tube gauging device. The length of the dip tube must be such that when a liquefied petroleum gas, with a specific volume of 0.03051 cu. ft./lb. at a temperature of 40 °F, is filled into the container, the liquid just reaches the bottom of the tube. The weight of this liquid may not exceed 42 percent of the water capacity of the container, which must be stamped on the cylinder. The length of the dip tube, expressed in inches carried out to one decimal place and prefixed with the letters “DT”, must be stamped on the container and on the exterior of removable type dip tube. For the purpose of this requirement, the marked length must be expressed as the distance measured along the axis of a straight tube from the top of the boss through which the tube is inserted to the proper level of the liquid in the container. The length of each dip tube must be checked when installed by weighing each container after filling except when installed in groups of substantially identical containers, in which case one of each 25 containers must be weighed. The quantity of liquefied gas in each container must be checked by means of the dip tube after disconnecting from the filling line. The outlet from the dip tube may not be larger than 0.1016 centimeters (0.040 inch; No. 54 drill bit size orifice). A container representative of each day's filling at each filling plant must have its contents checked by weighing after disconnecting from the filling line.

(e) *Carbon dioxide, refrigerated liquid or nitrous oxide, refrigerated liquid.* (1) The following provisions apply to carbon dioxide, refrigerated liquid, and nitrous oxide, refrigerated liquid:

(i) DOT 4L cylinders conforming to the provisions of this paragraph are authorized.

(ii) Each cylinder must be protected with at least one pressure relief device and at least one frangible disc conforming to § 173.301(f) and paragraph (a)(2) of this section. The relieving capacity of the pressure relief device system must be equal to or greater than that calculated by the applicable formula in paragraph 5.8.3 of CGA S-1.1 (IBR, see § 171.7 of this subchapter).

(iii) The temperature and pressure of the gas at the time the shipment is offered for transportation may not exceed −18 °C (0 °F) and 290 psig for carbon dioxide and −15.6 °C (+4 °F) and 290 psig for nitrous oxide. Maximum time in transit may not exceed 120 hours.

(2) The following pressure relief device settings, design service temperatures and filling densities apply:

Pressure relief device setting maximum start - to discharge gauge pressure in psig | Maximum permitted filling density
(percent by weight) | |
---|---|---|

Carbon dioxide, refrigerated liquid | Nitrous oxide, refrigerated liquid | |

105 psig | 108 | 104 |

170 psig | 105 | 101 |

230 psig | 104 | 99 |

295 psig | 102 | 97 |

360 psig | 100 | 95 |

450 psig | 98 | 83 |

540 psig | 92 | 87 |

625 psig | 86 | 80 |

Design service temperature °C (°F) | −196 °C (−320 °F) | −196 °C (−320 °F) |