Mann Tek, a Swedish company and coupling manufacturer, posted an interesting video showing a bunkering operation between a bunker vessel and a passenger ferry.
https://www.youtube.com/watch?v=23qI78ZF3Q8
The Dry Cryogenic Coupling (LNG coupling) consists of a “tank” unit which is a type of a non-return valve and a “hose” unit with a valve driven by an internal cam curve to open both valves at the same time.
The operation is a single action using a straight forward turning motion to connect the couplings and open flow path.
An initial push and turn action on the hose unit provides engagement with the tank unit, thus locking and sealing the two units together.
This is followed by further rotation opening the internal valves, thereby allowing full flow with a minimum of pressure drop.
A selectivity (code) system allows the system to be used to a wide range of cryogenic liquefied gases without any risk of failure owing to “human error”.
[mappress] LNG World News Staff, January 28, 2013