Traditionally, the loading of volatile liquids such as petroleum, kerosene, and diesel involved loading and withdrawing the liquid fuels from an aboveground tank or tanker that had an opening at the top. With liquids that are extremely volatile, highly flammable vapors are created in the tank itself, which are usually released into the air when the opening at the top was opened. These vapors are an environment hazard and cause pollution.
In order to solve this problem, engineers decided to create an opening in the sidewall of the tanker truck, near the bottom of the tank for loading and unloading the oil products. Through this process, the gasoline was loaded above the usual level of liquid that was already present in the tank. This process came to be known as the Bottom Loading procedure which substantially reduced the amount of vapors formed during the filling the process.
Although it is easy to understand the process of bottom loading of volatile liquids, it is actually quite difficult to build a system that worked on this principle. It required creating a coupling and valve system that would enable a tight connection between the delivery hose and the tank. A loading valve was needed to be built in the bottom of the tank that would not open until the delivery hose was securely in place so that the valve will remain closed till the delivery hose gets disconnected.
It is now common practice to load tanks through bottom loading. Some of the advantages of the system are as follows:
- The safety of the person loading and unloading the liquid is improved dramatically as he is on the ground and not on top of the truck from where trips or falls are a known risk
- Overall loading time is reduced as the bottom loading and unloading connections can be made more quickly.
- There is less turbulence in the tank owing to bottom loading of the tank which significantly reduces the danger of generating static electricity.
- There is less formation of vapors.
- The system can be tweaked to fully recover the vapors that get displaced during loading.
- It is easier and more economical to build bottom loading arms than top loading racks, thereby increasing the savings for the company.
- They load more material in less time with much less spillage with a provision to recover the vapors completely.
Bottom Loading Equipment Design
Bottom loading arms are designed in such a way that they get connected on the side or on the back of the tanker and sometimes at both these positions for filling 2 compartments simultaneously. They are provided with swivel joints and a spring cylinder for balancing. For keeping the connection pipe in a horizontal position, they are equipped with a pantograph. There are several other accessories that come with the equipment in order to increase the safety and decrease dangers associated with the gas loading process.
We hope this blog has increased your knowledge of the design and engineering excellence that this equipment has incorporated to make loading and unloading a much simpler and safer process.