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Gas Cylinder Connection Standards for Germany

Standards for Gas Cylinder and Diving Cylinder Valves in Germany

Gas cylinder and diving cylinder valves in Germany are subject to clearly defined standards that ensure safety, compatibility, and reliability. The most important standards in this area include DIN 477, DIN EN 144, and DIN EN ISO 12209. These standards build on each other and are closely linked.

Historically, only DIN 477 was originally valid. From this, DIN EN 144 was developed, specifically regulating the requirements for valves and connections for breathing and diving equipment. With the introduction of DIN EN ISO 12209, the international yoke connection (INT) was also integrated, taking global standards into account.

DIN 477 – Connections for Compressed Gas Cylinders
DIN 477 regulates the connections of gas cylinder valves and ensures that compressed gas cylinders are equipped with safe and standardized connections. This standard prevents connection mix-ups through clear definitions and ensures reliable sealing between the gas cylinder and attached devices.

Subdivision of DIN 477

DIN 477 is divided into two main areas:

DIN 477-1: Regulates the connections for valves in the pressure range up to 200 bar.
DIN 477-5: Applies to connections in the pressure range up to 300 bar.

Details of DIN 477-1: Connection Types and Threads
DIN 477-1 defines a variety of connections for different gases and applications. Here is an overview of the most important connections:

 
Connection No. 1 & 2: W21.8x1/14 LH external thread: Outer diameter of 21.8 mm and pitch of 1/14 inch (1.814 mm), with left-hand thread. Use: Flammable gases such as propane and butane.

Connection No. 3: Clamp connection: Used for acetylene in welding and cutting applications.

Connection No. 4: G3/8" LH external thread: Specifically for smaller cylinders up to 1 liter, e.g., soldering kits.

Connection No. 5: 1" LH external thread: Used for rare or toxic gases such as hydrogen cyanide or carbon monoxide.

Connection No. 6: W21.8x1/14" external thread: Most common thread in welding technology for shielding and forming gases. Also used in aquaristics and beer dispensing systems.

Connection No. 7: G5/8" external thread: For sulfur dioxide. Not to be confused with the G5/8" thread from the diving sector.

Connection No. 8: 1" external thread: For special gases such as hydrogen chloride or bromine chloride.

Connection No. 9: G3/4" external thread: Known from crafts, diving, medical, and aviation applications. Outer diameter of 26.4 mm, pitch of 1/14 inch (1.814 mm).

Connection No. 10: W24.32x1/14" external thread: Used for nitrogen and nitrogen mixtures.

Connection No. 11 & 12: No. 11: G3/8" external thread: For nitrous oxide (laughing gas). No. 12: G3/4" internal thread: For cylinders up to 3 liters with nitrous oxide.

Connection No. 13: G5/8" internal thread: For breathing air or compressed air. Corresponds to the specifications of DIN EN 144-2 and DIN EN ISO 12209. Different standards for 200 and 300 bar as well as breathing air according to DIN EN 12021.

Connection No. 14: M19x1.5 LH external thread: For test gases, especially in air conditioning technology.

Connection No. 15: W21.8x1/14 LH internal thread: Used for methylacetylene and propadiene mixtures.



DIN EN 144 – Requirements for Valves for Diving and Breathing Air Cylinders

DIN EN 144 includes a series of subcategories that deal with valves for compressed gas cylinders in diving sports: 

  • DIN EN 144-1 "Respiratory protective devices - Gas cylinder valves - Part 1: Thread connection at the screw-in nozzle": Regulates the threads at the valve inlet (cylinder neck thread) such as M18x1.5, M25x2, E17 taper thread
  • DIN EN 144-2 "Respiratory protective devices - Gas cylinder valves - Part 2: Thread connections at the outlet nozzle": Refers to valves for breathable gases used in diving and respiratory protection technology with G5/8", M24x2, M22x1.5, and M20x1.5
  • DIN EN 144-3 "Respiratory protective devices - Gas cylinder valves - Part 3: Thread connections at the outlet nozzle for diving gases Nitrox and Oxygen": Covers connections for gas mixtures with increased oxygen content such as Nitrox or Trimix with M26x2



DIN EN ISO 12209 – Requirements for Valves for Diving and Breathing Air Cylinders Including the INT Yoke Connection

DIN EN ISO 12209 "Gas cylinders - Outlet connections for gas cylinder valves for compressed breathing air" describes the requirements for regulator connections for G5/8" 232 bar and 300 bar according to EN 144-2 as well as 500 bar and outlet connections for scuba applications (yoke connection).

Why are these standards essential? Compliance with these standards guarantees:
- Maximum safety: Standardized connections minimize the risk of misapplications. 
- Compatibility: Devices manufactured according to these standards are guaranteed to be compatible with each other. 
Our products comply with all relevant specifications of DIN 477, DIN EN 144, and DIN EN ISO 12209 to provide you with the highest level of safety and reliability.
If you have any questions about these standards or their application, we are happy to assist you.