What is the difference between top-loading and bottom-loading?
The tank of a tanker is divided into different compartments or pockets. These are loaded with liquid fuel products such as heating oil (also known as fuel oil, red diesel, or off-road diesel), diesel, petrol, petroleum, etc. This loading of such a compartment can be done in two ways: top-loading or bottom-loading.
Top-loading
The driver stands on top of the tanker’s tank. They then insert the loading arm of the depot installation through the manhole into the compartment of the tanker. In Europe, this type of loading is becoming less common for safety and health reasons. Outside Europe, however, loading usually takes place via top-loading.
Bottom-loading
Bottom-loading is an optional installation on the tanker. Liquid fuel products are pumped to the desired compartment via the API coupling from the installation box at the bottom of the side of the truck.
A bottom-loading installation can be equipped with one or two central couplings. A coupling can also be provided for each compartment separately. This way, no contamination of products occurs. Since this makes it possible to load two or more compartments simultaneously, it also saves time.
With bottom-loading, it is also necessary to provide the following safety measures:
- Breather valve
Because the liquid product is pumped from below into a completely sealed tank compartment, the residual gases present in the tank could become compressed. Therefore, a breather valve must be opened at the top. This way, the gases can be recovered. - Sensors or probes
‘Sensors’ or ‘probes’ must also be installed in the compartments. These seal the compartment in good time and safely before the maximum permissible volume is reached. - Vapour return line
- Overfill protection connector
- Earthing
Top- or bottom-loading?
Before buying a tanker, you should first decide whether you want to work with top- or bottom-loading, or if you need both options. A tanker with only top-loading is very difficult or even impossible to convert into a bottom-loading tanker afterwards.
The TVW Fuel Trucks range includes both tankers with bottom- and top-loading or we can convert a tanker with only bottom-loading so that top-loading is also possible. Other adaptations such as specific bodywork and paintwork as well as functional adjustments to the ADR system are also possible. So TVW Fuel Trucks always gives you a tanker that meets your needs.