of this section no carboy or other container of nitric acid shall be loaded above any container containing any other kind of material. The loading of carboys or other containers of nitric acid shall be limited to two tiers high.

(b) Carboys and frangible containers. In general, individual carboys and frangible containers of acids or other corrosive liquids, including charged electric storage batteries, shall, when loaded by hand, be individually loaded into and unloaded from any motor vehicle in which they are to be, or have been, transported. All reasonable precautions shall be taken to prevent, by all practicable means, the dropping of any such containers or batteries containing corrosive liquids. No such container or battery shall be loaded into a motor vehicle having an uneven floor surface. It shall be permissible to load on or transport in any motor vehicle any authorized carboys or frangible shipping containers, containing acids or other corrosive liquids, more than one tier high above any floor only if such carboys or other containers are boxed or crated, or are in barrels or kegs, as required by Parts 170-189 of this chapter, and only if such containers are so stacked that the weight of each tier above the first is entirely supported by the boxes, crates, barrels, kegs, or other authorized means of enclosing the carboys or frangible containers. Only 80 many tiers as may adequately be so supported without danger of crushing or breaking, shall be permitted. Means shall be provided to prevent by all practicable means, in all cases, the shifting of containers or batteries during transit. Nothing contained in this section shall be so construed as to prevent the use of cleats or other retaining means for the purpose of preventing shifting of containers or batteries. For the purposes of this section a false floor or platform, secured against relative motion within the body of the motor vehicle, shall be deemed to be a floor. (For recommendations for handling leaking or broken packages, see § 177.858 (a).)

(c) Storage batteries. In addition to the requirements set forth in paragraph (b) of this section, all storage batteries containing any electrolyte shall be so loaded, if loaded with other lading, that all such batteries will be protected against other lading falling onto or against them; and adequate means shall be provided in all cases for the protec

tion and insulation of battery terminals against short circuits.

(18 U.S.C. 831-835; sec. 9, 49 U.S.C. 1657) [29 F.R. 18795, Dec. 29, 1964, as amended by Amdt. 177-10, 35 F.R. 1110, Jan. 28, 1970] § 177.840 Compressed gases. (See also § 177.834 (a) to (k).)

(a) Floors or platforms essentially flat. Cylinders containing compressed gases shall not be loaded onto any part of the floor or platform of any motor vehicle which is not essentially flat; cylinders containing compressed gases may be loaded onto any motor vehicle not having a floor or platform only if such motor vehicle be equipped with suitable racks having adequate means for securing such cylinders in place therein. Nothing contained in this section shall be so construed as to prohibit the loading of such cylinders on any motor vehicle having a floor or platform and racks as hereinbefore described.

(1) Cylinders. To prevent their overturning, cylinders containing compressed gases must be securely lashed in an upright position; loaded into racks securely attached to the motor vehicle; packed in boxes or crates of such dimensions as to prevent their overturning; or loaded in a horizontal position. Specification DOT-4L cylinders must be loaded in an upright position and securely braced.

(2) Cylinders for liquefied hydrogen. Specification DOT-4L cylinders containing liquefied hydrogen must be transported only on motor vehicles with open bodies which are equipped with suitable racks or supports having clamps or securing bands capable of holding the cylinders upright when they are subjected to an acceleration of at least 2 "g" in any horizontal direction.

(i) The combined total of the hydrogen venting rates as marked on the cylinders on one motor vehicle must not exceed 60 standard cubic feet per hour.

(ii) Motor vehicles loaded with cylinders containing liquefied hydrogen may not be driven through tunnels.

(iii) Highway transportation is limited to private and contract motor carriers only and to direct movement from point of origin to destination.

(b) Portable tank containers containing compressed gases shall be loaded on motor vehicles only as follows:

(1) Onto a flat floor or platform of a motor vehicle.

(2) Onto a suitable frame of a motor vehicle.

(3) In either such case, such containers shall be safely and securely blocked or held down to prevent movement relative to each other or to the supporting structure when in transit, particularly during sudden starts and stops and changes of direction of the vehicle.

(4) Requirements of subparagraphs (1) and (2) of this paragraph shall not be construed as prohibiting stacking of containers, provided the provisions of subparagraph (3) of this paragraph are fully complied with.

(c) [Reserved]

(d) Engine to be stopped in tank motor vehicles, except for transfer pump. No flammable compressed gas shall be loaded into or on or unloaded from any tank motor vehicle with the engine running unless the engine is used for the operation of the transfer pump of the vehicle. Unless the delivery hose is equipped with a shut-off valve at its discharge end, the engine of the motor vehicle shall be stopped at the finish of such loading or unloading operation while the filling or discharge connections are disconnected.

(e) Chlorine cargo tanks shall be shipped only when equipped (1) with a gas mask of a type approved by the U.S. Bureau of Mines for chlorine service; (2) with an emergency kit for controlling leaks in fittings on the dome cover plate.

(f) No chlorine tank motor vehicle used for transportation of chlorine shall be moved, coupled or uncoupled, when any loading or unloading connections are attached to the vehicle, nor shall any semi-trailer or trailer be left without the power unit unless such semitrailer or trailer be checked or equivalent means be provided to prevent motion.

(18 U.S.C. 831-835; sec. 9, 49 U.S.C. 1657) [29 F.R. 18795, Dec. 29, 1964, as amended by Amdt. 177-5, 34 F.R. 7162, May 1, 1969; Amdt. 177-10, 35 F.R. 1110, Jan. 28, 1970]

proof, steel hopper-type or dump-type with motor-vehicle bodies equipped water-proof, dust-proof covers well secured in place on all openings, to accomplish such loading with the minimum spread of such compounds into the atmosphere by all means that are practicable; and no such loading or unloading shall be done near or adjacent to any place where there are or are likely to be, during the loading or unloading process assemblages of persons other than those engaged in the loading or unloading process, or upon any public highway or in any public place.

(1) The motor vehicles must be marked in accordance with § 173.368 (b) of this chapter.

(2) Before any motor vehicle may be used for transporting any other articles, all detectable traces of arsenical materials must be removed therefrom by flushing with water,or by other appropriate method, and the marking removed.

(b) No class A or class C poisons in cargo tanks. No dangerous poison, class A. or any tear gas or irritating substance, class C, may be loaded into or transported in any cargo tank.

(c) Class A or class C poisons. It shall not be permissible to transport class A or class C poisons if there be any interconnecting means of any character between the containers.

(d) [Reserved]

(e) Material marked as or known to be poison (class A or B) must not be transported in the same vehicle with material which is marked as or known to be foodstuffs, feeds, or any other edible material intended for consumption by humans or animals.

(18 U.S.C. 831-835; sec. 9, 49 U.S.C. 1657) [29 F.R. 18795, Dec. 29, 1964, as amended by Amdt. 177-3, 33 F.R. 14933, Oct. 4, 1968; Amdt. 177-5, 34 F.R. 7163, May 1, 1969; Amdt. 177-9, 34 F.R. 18554, Nov. 21, 1969; Amdt. 177-10, 35 F.R. 1110, Jan. 28, 1970]

§ 177.842 Radioactive material.

(a) The number of packages of radioactive materials, as provided for in §§ 173.393 through 173.396 of this chapter, in any motor vehicle, trailer or storage location must be limited so that the total transport index number, as defined in § 173.389 (h) of this chapter, and de

termined by adding together the transport index numbers shown on the labels of the individual packages does not exceed 50. This provision does not apply to sole-use shipments described in § 173.393 (j) or (k) or § 173.397 of this chapter.

(b) Packages of radioactive material bearing "radioactive yellow II" or "radioactive yellow-III" labels shall not be placed in motor vehicles or other places closer than the distances shown in the following table to any area which may be continuously occupied by passengers, employees, or shipments of animals. nor closer than the distances shown in the table below to any package containing undeveloped film (if so marked). If more

than one of these packages is present, the distance shall be computed from the following table on the basis of the total transport index number (determined by adding together the transport index numbers on the labels of the individual packages) of packages in the vehicle or storeroom.

(c) Shipments of low specific activity materials, as defined in § 173.391 of this chapter, must be loaded so as to avoid spillage and scattering of loose materials. Loading restrictions are set forth in § 173.397 of this chapter.

(d) Packages must be so blocked and braced that they cannot change position during conditions normally incident to transportation.

surface contamination (see § 173.399 of this chapter).

(b) This section does not apply to any vehicle used solely for transporting radioactive material if a survey of the interior surface shows that the radiation dose rate does not exceed 10 millirem per hour at the interior surface or 2 millirem per hour at 3 feet from any interior surface. These vehicles must be stenciled with the words "For Radioactive Materials Use Only" in lettering at least 3 inches high in a conspicuous place, on both sides of the exterior of the vehicle. These vehicles must be kept closed at all times other than loading and unloading.

(c) In case of fire, accident, breakage, or unusual delay involving shipments of radioactive material, see § 177.861. [Amdt. 177-3, 33 F.R. 14933, Oct. 4, 1968]