What is Yoke?
The yoke fitting is the “standard” fitting that comes on most regulators and most tank valves. A yoke is also called an “A-Clamp” or an “international” fitting.
What is DIN?
(Deutsches Institut für Normung) DIN is a screw in fitting. Instead of clamping onto valve, it screws into it. There are two types of DIN: Five thread 232 BAR and seven thread 300 BAR; both have the same threading, but a 300 BAR valve is deeper. A 300 BAR regulator will fit into either a 300 BAR or a 232 BAR DIN fitting. However, the 232 BAR regulator will not work on a 300 BAR cylinder as it will not screw all the way in.
DIN is “safer”. That is, the ‘O’ ring is captured inside the valve and it is very hard for it to blow or squeeze out. DIN is cleaner, meaning there is no screw knob sticking out the back of the valve, a knob that can be entangled on something or even sheared off. The only problem with a DIN regulator is that they are not standard. When a diver goes on vacation, they are most likely to get a yoke valve tank. So what should you do, have a yoke adaptor.
How do you convert your regulator?
The easiest way is to buy your regulator with a DIN fitting. Most regulators are available with DIN as an option at no extra cost, but you will have to order it. Most dive shops do not carry regulators with DIN. If you have a yoke regulator, you can have it converted. A conversion kit may cost $50 or more. Your dive shop can do the installation, it is a very simple procedure.
What is a pro-valve?
Nowadays, the bulk of US cylinder comes with pro-valves. These are DIN valves in which the manufactures place a small “insert” into the valve to make it into an yoke valve! All you have to do is remove this insert with a hexagonal key and what is revealed is a 5 thread DIN fitting. Inserts only come in 5 threads, so you cannot convert a 7 thread 300 BAR valve to A-Clamp. Keep the insert in your save a dive kit. You may need it if the fill station does not have a DIN filling whip or you want to use your cylinder with a yoke regulator.
What About Diving Overseas?
The Caribbean is the only place where getting a DIN cylinder is just about impossible for normal recreational diving. Any place frequented by mainly American divers may be limited to yoke. DIN will dominate anywhere visited regularly by Europeans, especially the Germans. In those areas, you will have to ask for a yoke valve. If you have converted your regulators from yoke to DIN then you should have an adaptor and you can dive either tank.