A loading rack is a structure that provides for the overhead loading of liquid materials such as chemicals and petroleum products into tanker trucks or railcars. Variable size units allow for loading one or more tankers at the same time. Pumping equipment in the loading rack or at storage tanks draws product and moves it into the transport vehicle. Loaded volume may be determined by metering or weight calculations. A number of safety features are specified for a loading rack.
The structure of a loading rack resembles a walkway with branches leading off it to give workers access to the loading ports on the top of railcars or tankers. A loading rack may be designed to service only one transport vehicle or several. For railcars, a multistation rack is linear, to accommodate the track structure. For tanker trucks, the configuration may support side-by-side loading, front-and-back positioning, or both. The construction can be open-air or covered with a canopy to protect the process from weather.
The framework of the loading rack can support loading arms that move into position over the openings in the tanker. To accommodate railcars and tank trailers with multiple compartments that must be loaded separately, loading arms are often mounted on a rail or movable assembly. This allows all compartments to be filled without moving the tanker. Some delivery setups use a hose and nozzle for filling.
Pumps move the product from storage to the tankers. The vast majority of pumps on loading systems operate on electricity. The size and pressure of the required pump varies based on the distance the product has to travel from the storage tanks and what size pipe it travels through.
The volume of material loaded can be measured by metering the flow. Some petroleum facilities use the gross and tare weight of the tanker and calculate the delivered quantity using the API gravity. Upon completion of loading, a bill of lading or manifest is issued to accompany the load to its final destination.
Modern loading racks incorporate safety equipment such as harnessing systems to provide fall protection for workers operating on top of tankers. Posted warnings advise drivers of trailer height restrictions. For loading low-flashpoint petroleum products such as gasoline, grounding is essential to prevent combustion from static electricity. Grounding is accomplished using a cable connected to the loading rack, the tanker being loaded, and the earth. If the material produces volatile vapors, a vapor recovery system may be required.