Which coupling is suitable for loading and unloading tank trucks?

There is no single coupling system in use throughout Europe. The choice often depends on the country, the sector and the existing installation you are connecting to:

• Cam and groove couplings (camlock): quick to connect and disconnect using levers and widely used on tank equipment.
• Tanker couplings (TW): also commonly referred to as Elaflex couplings, with designations such as MK and VK in sizes of 2, 3 and 4 inches (VK 50, VK 80 and VK 100). The prevailing standard, particularly in Germany.
• Guillemin couplings: bayonet couplings used mainly in France.
• Storz couplings: bayonet couplings for water and the standard used by fire brigades, among others. As they are usually made of aluminium, they are not intended for chemicals. Also see the water couplings.
• Flange couplings: two flanges joined with bolts and nuts. This connection cannot open unintentionally and is therefore widely used on bunker hoses and chemical hoses, where safety and pressure are paramount.

If you are connecting to existing equipment, that connection usually determines the system. SCHIEMA advises on the coupling that suits your medium, pressure and installation, and assembles the complete hose assembly.

You need a dry disconnect coupling when not a single drop of product or any vapour may escape on disconnection, because it is harmful to people or the environment. This applies, for example, when loading and unloading tank trucks and tank containers and on pipelines in the (petro)chemical industry.

A dry disconnect coupling consists of a male part, the tank unit (on the tank or pipeline), and a female part, the hose unit (on the hose). Both parts contain check valves. When connecting and rotating, the valves open to create a free passage; when disconnecting, they close completely again so that nothing leaks out.

Well-known systems include TODO-MATIC and Mann Tek. Various brands work on the same principle and are in many cases interchangeable; do check this for each version. Where several products are loaded or unloaded side by side, dry disconnect couplings can be fitted with selectivity coding. This prevents, for example, a diesel hose from being connected to a kerosene connection.

A food coupling is designed so that there is no gap in which product or contamination can remain. The coupling is therefore crimped onto the hose as standard, leaving no space between the hose tail and the hose. The connections themselves are also designed so that nothing can get in between.

With a standard water coupling, this hardly matters, as some contamination is not a problem with industrial or rinsing water, for example. The difference becomes relevant as soon as the medium is a foodstuff, such as dairy, juices or beverages, or when drinking water is involved. Hygiene and cleanability then determine the choice.