“Everything you ever wanted to know about tank valves but were afraid to ask.”
Most SCUBA divers are quite familiar with the lowly “K-Valve” that works with the yoke fitting on most regulators. It is the standard on the “aluminum 80” that the majority of us learned to dive with and that inhabits tank racks on dive boats everywhere. Occasionally, and more commonly in recent years, we see something called the DIN valve. What is it, what is it for, and what makes it so special?
If you don’t know the answers to these questions don’t feel bad, because there is even some confusion out there as to what the acronym actually stands for. It is Deutsches Institut fur Normung which translates to the German Institute for Standardization. DIN is the German national organization for standardization, based in Berlin. At this time there are around thirty thousand DIN Standards that cover nearly every field of technology. There is confusion over the acronym’s meaning and it is often incorrectly expanded as Deutsche Industrienorm or German Industry Standard in English. This is due to the historic origin of the DIN. The predecessor, NADI was founded in 1917 as the Normenausschuss der deutschen Industrie or in English- Standardization Committee of German Industry. The NADI was renamed Deutscher Normenausschuss – DNA or German Standardization Committee in 1926 because that organization dealt with standardization issues in many fields, not just for industrial products. In 1975 it was renamed again to what we know today as Deutsches Institut fur Normung, or DIN and is recognized by the German government as the official national standards body. So, why the confusion? The NADI published their standards as DI-Norm for Deutsche Industrienorm and many people still mistakenly associate DIN with the old DI-Norm naming method. So now you can impress your friends with the correct name, but what is a DIN valve and why do we choose to use them?
The DIN valve has been around for many years but, like other technological advances, there was competitive pressure and for a variety of reasons another variation of valve technology became the standard for SCUBA diving, namely the venerable yoke fitting. So, even though both types of valves were available back in the pioneering days of SCUBA diving, the yoke fitting became the generally accepted standard and is the most popular today.
The DIN valve was first introduced in the United States by Poseidon around 1958 or 1959 and called the “5/8 inch threaded connection” in their literature. Possibly the fact that Poseidon, a European company, was the lone provider, the DIN valve never saw widespread use. Over time, divers who were moving beyond the ordinary world of recreational SCUBA by diving in caves and other harsh environments realized the advantages of the DIN fitting and it began to see more use. In recent years it has come into popular demand, primarily among technical divers, and all for a good reason. It is a tougher, more reliable connection that will withstand the abuse of harsh diving conditions encountered in the technical diving world.
So, you ask, what is so special about the DIN valve? With a DIN valve, the first stage regulator screws into the valve and with a yoke valve the first stage regulator attaches by slipping over the valve and clamping with a tightening screw. The DIN valve attachment is far superior for numerous reasons. A DIN valve uses a captured o-ring that is behind the regulator post, eliminating the chance that it may extrude and cause gas loss. With the o-ring in the regulator it is less likely to be damaged or lost and is usually inspected more often than one on the tank valve. DIN regulators typically are designed to withstand higher pressures than yoke regulators, making them ideal for the high pressure fills encountered in technical diving. With a hard impact a yoke can be knocked off the tank, causing a catastrophic gas loss, whereas a DIN valve is secure and it is nearly impossible for one to be knocked off. DIN regulators are much more streamlined than yoke regulators, and generally weigh less. For diving in conditions where failure is not an option, like cave diving, wreck penetration, or deep technical diving, the DIN valve offers a superior alternative that eliminates some of the risk. So, for divers planning to engage in technical diving or who use high pressure tanks the DIN valve is preferred.
Since many of us dive in different locations and often are forced to use rental tanks, manufacturers have provided us with handy adaptors that allow yoke type regulators to be used on DIN tank valves or DIN regulators to be used on yoke tank valves. There is a DIN insert that can be screwed into a DIN valve allowing the use of a yoke regulator and a DIN to yoke adaptor that allows a DIN regulator to be used on a yoke type tank valve. Savvy divers carry both in their Save A Dive Kit to be ready for any type of valve they encounter.
With all this information, the next question is “Which valve is right for me?” Although the DIN valve has been gaining in popularity in recent years, the old standby yoke valve is still the right choice for the majority of divers. The tank we most often encounter, the Aluminum 80, generally is equipped with a yoke type valve and most regulators in the United States are sold with a yoke fitting. It is simple, easy to use and maintain, and it works fine in the conditions most recreational divers will dive in. For those divers wishing to pursue any type of technical diving the DIN valve is recommended. Because of its superior qualities in the environments likely to be encountered it is safer. It will also be more common at the dive shops you deal with, as it is used almost exclusively for cave diving, deep wreck penetration, decompression diving, and rebreather diving.
With this information in hand you can choose the type of equipment you want to use. Whatever equipment you dive with and however you dive, the most important points to remember is to get good training, gain experience, buy from a reputable dealer, and then always dive within the scope and limitations of those three things: training, experience, and equipment.