API MPMS 3.2:1995(R2013) pdf download.Manual of Petroleum Measurement Standards Chapter 3—Tank Gauging
3.2.4 Safety and Health Considerations
Caution: All applicable safety and health procedures should be consulted. Considerations should include, but are not limited to, potential electrostatic and other fire and explosion hazards, potential personnel exposure (for example, expo- sure limits, hazard communication, training, associated protective clothing and equipment requirements, and work practices), and potential explosive and toxic hazards associ- ated with a tank car’s atmosphere. The physical characteris- tics of the commodity and existing operational conditions should be evaluated, and applicable international, federal, state, and local regulations should be observed. Safety proce- dures designated by the employer and other concerned parties should also be observed. The Association of Amer- ican Railroads Manual of Standard Recommended Practices and API publications provide additional safety information and should be consulted. Caution: Petroleum vapors and associated substances may also involve potential toxicity, including hydrogen sulfide vapors from “sour” crude. Petroleum vapors with high concentrations of hydrogen sulfide may cause unconscious- ness or death. During and after the opening of the manway, one should stand so that vapor inhalation is minimized. Harmful vapors or oxygen deficiency cannot be detected safely by smell, visual inspection, or judgment. Appropriate precautions should be used for protection against toxic vapors or oxygen deficiency. Procedures should be devel- oped to provide for appropriate exposure monitoring, personal protective equipment, and emergency rescue precautions. When necessary, suitable respirator protection should be worn prior to entering the gauge site and during the gauging procedure.
3.2.7 Definitions
3.2.7.1 A capacity table (also, tank capacity table, calibra- tion table) is a table showing the tank car capacities or volumes for various liquid levels measured at the reference gauge point. 3.2.7.2 Dome tank cars are non-pressure tank cars with an expansion trunk (dome) at the top center of the tank car to provide space for expansion of the liquid in the car. The manway opening is on the dome. 3.2.7.3 D omeless tank cars are tank cars with the manway opening attached directly to the top of the tank car shell (see Figure 1). 3.2.7.4 Interior lining is the surface coating applied to the interior of a tank car shell to prevent contents from contacting the metal shell. Linings may be damaged if gauging equipment is not used carefully. 3.2.7.5 Magnetic gauging device (also, magnetic float gauge) is a gauging device fitted to a tank car to permit measuring the liquid level in the car without opening the car to the atmosphere. The device consists of two magnets: one fitted inside a float and one affixed to a graduated gauge rod or tape. When the two magnets link, the gauge is read at the reference gauge point. 3.2.7.6 Markers are metal liquid-level indicators installed in domeless tank cars, usually at the level where the car is filled to 98 percent of capacity; however, they are occasion- ally at other levels. Markers are not accurate measurement devices. Markers are not recommended for custody transfer measurements.