Appurtenance. All devices that are added onto the system such as pumps, compressors, safety relief devices, liquid-level gauging devices, valves, and pressure gauges.

Capacity. The total volume of the container measured in U.S. gallons, unless otherwise specified.

Container. All vessels, tanks, cylinders or spheres used for transportation, storage or application of anhydrous ammonia.

Cylinder. A container constructed according to the United States Department of Transportation specifications with a water capacity of one thousand pounds or less.

Design pressure. The same as the "maximum allowable working pressure" as used in the Unfired Pressure Vessel Code.

DOT regulations. The department of transportation (DOT) hazardous materials regulations and specifications for shipping containers found in Title 49—Transportation, Code of Federal Regulations, Parts 171 to 190, inclusive.

Filling density. The ratio of the weight of the gas in a container to the weight of water at 60°F that the container will hold. One lb. H2O = 27.737 cu. in. at 60°F.

For determining the weight capacity of the tank in pounds, the weight of a gallon (231 cubic inches) of water at 60°F in air is 8.32828 pounds.

Gas. Anhydrous ammonia in either the gaseous or liquefied state.

Hydrostatic relief valve. An automatic pressure activated valve for liquid service.

(a) It is characterized by a throttle or slow weep opening, a nonpop-action.

(b) Refer to American National Standards Institute, Terminology for Pressure Relief Devices, B95.1, for more information.

"psig" and "psia." Abbreviations that mean the following:

(a) "psig" refers to pounds per square inch gauge.

(b) "psia" refers to absolute pounds per square inch.

Safety relief valve. An automatic spring loaded or equivalent type pressure activated device for gas or vapor service.

(a) It is characterized by a pop-action upon opening, and is sometimes referred to as a pop valve.

(b) Refer to American National Standards Institute, Terminology for Pressure Relief Devices, B95.1 for more information.

Semi-trailer. Every vehicle that meets both of the following:

(a) Designed for carrying property and for being drawn by a motor vehicle;

(b) Constructed so that some part of its weight and the weight of its load rests upon or is carried by another vehicle.

Systems. An assembly of equipment consisting of the container or containers, appurtenances, pumps, compressors, and interconnecting piping.

Tank motor vehicle. Any motor vehicle designed or used for the transportation of anhydrous ammonia that has either:

(a) A tank designed to be permanently attached to any motor vehicle; or

(b) A container that is not permanently attached but needs to be loaded and unloaded without being removed from the motor vehicle due to its size, construction, or means of attachment.

Trailer. Every vehicle meeting all of the following:

(a) Designed for carrying property and for being drawn by a motor vehicle;

(b) Constructed so that no part of its weight except the towing device rests on the towing vehicle.