According to ISO 21593
the international standard that specifically addresses the technical requirements for LNG (Liquefied Natural Gas) couplings. The primary objective of ISO 21593 is to establish uniform technical specifications and safety protocols for LNG couplings used in different scenarios and under diverse conditions. It aims to guarantee that these couplings are compatible not only within their own manufacturer’s range but also with other manufacturers’ products that meet the same ISO standard.
According to MannTek manufacturer's Standard
The Standard Coupling (Older Model) is recommended for continued use if it is already in operation. This standard was developed before the ISO 21593 Standard existed.