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CHEMICALS AND CHEMICAL HANDLING 15.3

able containers, such as chlorine cylinders or ton containers, may be subject to demur-
rage charges unless these are waived by agreement in the purchase contract.

Delivery, Handling, and Storage of Chemicals

Modes of transporting chemicals include railroad tank cars, trucks, and, in rare instances,
barges. The type of unloading facilities depends on whether chemicals arrive in bags, drums,
or bulk; the form in which the chemical will be fed to the process; the type of carder (rail
or truck); and the location and type of storage silo, tank, or other storage facility.

Receiving Shipments. Whether the chemical is liquid or solid, truck delivery is usually
preferred because of its simplicity, maneuverability, and generally prompt and predictable
delivery. In contrast to rail shipments, truck delivery makes more load size options avail-
able while still preserving the economies of bulk purchasing. Modem air-slide and pneu-
matic unloading equipment on these vehicles permits quick and easy delivery of bulk
loads below grade and to overhead silos.
Unloading platforms or docks must be provided in all but the smallest plants to ac-
commodate truck deliveries of containerized chemicals, including bagged material, drums,
small gas cylinders, and the like. Horizontal transport of nonbulk chemicals from the un-
loading dock is normally accomplished by hand or power trucks, conveyors, or a mono-
rail system. Storage in areas above or below the unloading area requires installation of an
inclined conveyor, dock leveler, hoist, or elevator designed for the maximum anticipated
loads.
Receiving and Storing Pressurized, Liquefied Gases. Gases commonly used in water
treatment are chlorine and ammonia for disinfection processes and carbon dioxide for sta-
bilization and pH control after softening. Oxygen is sometimes used for the gas feed to
ozonation generators. All these gases are shipped as pressurized liquids. Carbon dioxide
and oxygen are refrigerated in their liquid state.
Chlorine. Chlorine used in the water industry is seldom stored in on-site receivers.
Instead, the shipping container is used for storage. If chlorine is received at a treatment
plant in a tank truck or barge, a sufficient pressure differential must be maintained be-
tween the shipping container and the storage container during transfer.
Gaseous chlorine is commercially available in containers of the following sizes:
• 150-1b cylinders
• 1-ton cylinders
• 15- to 17-ton tank trucks
• 16- to 90-ton railroad tank cars
Cylinders of 100-1b (45-kg) weight are also available, but are rarely used. The di-
mensions of the 150-1b (68-kg) and 1-ton (907-kg) cylinders are shown in Figure 15.1.
Because chlorine tank trucks do not have standard sizes, dimensions should be obtained
from local chlorine suppliers.
In all the containers listed above, liquid chlorine occupies a maximum of approxi-
mately 85% of the volume when the product is delivered. This 15% allowance provides
room for liquid chlorine to expand if the cylinder becomes warm. No chlorine container
should ever be directly heated. If the liquid were to become warm enough to expand and
fill the entire container, tremendous hydrostatic pressure would result, and the container
would rupture. As a safety precaution, cylinder outlet valves are equipped with a small