When do I need a dry disconnect coupling instead of a standard coupling?

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.

For loading and unloading tank trucks, dry disconnect couplings, tanker couplings (TW) and cam and groove couplings (camlock) are mainly used. For products that must not leak or release vapour, a dry disconnect coupling is the safest choice: on disconnection, the check valves on both sides close immediately.

The difference from a regular flange coupling lies in speed and shut-off. A flange connection is fitted with bolts and nuts and is highly reliable under pressure, but it is not designed for frequent, quick connection and disconnection. A dry disconnect coupling is made precisely for frequent coupling without product loss.

Many companies also work with a dedicated hose: a hose used exclusively for one product, so that no residues of other products end up in it. Combined with an additional product valve on the coupling, this creates a very safe solution.

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.