Purposes Of A Top Loading Arm

by | Feb 7, 2014 | Construction and Maintenance

When you read about tankers, whether rail or truck, you may run across the expression “loading arm.” You may also see the terms top loading arm, bottom loading arm, pantographs or scissor arms, counterweighted loaders, vapour recovery loaders and wash arms. All refer to a specific method of loading or unloading cargos of specific liquids from one tank to another. This includes but is not limited to such fuels as oil and foodstuffs.

No matter what type of arm you choose, they still come in different designs and are available in different sizes and lengths. It depends upon the job for which they are required. One of the more common types of arms available is the top loading arm.

Top Loading Arm

Road or railroad tankers may have their load transferred using a top loading arm. This requires the fluid being removed through the top (dome) of the rail or truck tanker. The connection made through the arm may be:

Open: the manhole is not sealed. The contents being removed are not toxic

Semi-closed: the cone of the manhole of the tanker is accessed using a cone. The cone may also have a vapour hose attachment to prevent the vapours escaping into the atmosphere

Closed: A flange connects the arm and the top of the tanker. This is required when transferring all toxic, noxious or any type of dangerous substances

The nature of the substance to be unloaded, not the actual arm, will dictate which method of unloading using the top loading arm is required.

Construction of A Top Loading Arm

When it comes to physical construction of a front loading arm, it does not substantially differ from the make-up of other types of arms. The materials used are aluminium, carbon steel or low-temperature carbon steel. These metals are designed to handle highly corrosive and/or substances of high temperatures. Furthermore, to reinforce their ability to be anti-corrosive, manufacturers frequently line or coat them with a low flammable, highly resistant plastic. This is polytetrafluoroethylene (PTFE).

Other measures a manufacturer takes in ensuring the employees are safe and the arms work to their maximum capability include:

Seals: constructed of tough and resistant material

Swivel Joints: to provide flexibility

Counter Weights/Torsion springs: support movement made vertically

Supported booms: to provide a greater reach

Shut-off valves: to prevent potential problems from overflowing, etc.

Instrumentation equipment: to facilitate/monitor the unloading and to keep all involved safe

When it comes to unloading rail cars or the tankers of trucks, one of the most common and favourite types of arms is a top loading arm. Its construction and implementation are conducive to fast, efficient unloading or transferring of liquid substances.

Latest Articles