Unveiling the Truth Behind Scuba Tank Valve Operation: Fully Open or Quarter Turn Back?

In the early days of scuba diving, the operation of tank valves was shrouded in caution. Divers were advised to open the tank valve fully and then turn it back a quarter turn to avoid the risk of the valve getting stuck in the open position. However, as technology has advanced and equipment has evolved, the necessity of this practice has come into question.

Decades ago, the concern over tank valves getting stuck open was valid. Tanks and valves were constructed differently, and the fear of a valve locking in the open position or damaging the high pressure seat due to overtightening was a real possibility. However, with modern manufacturing standards and improved materials, this concern has become virtually obsolete. Tank valves today are designed to withstand the pressures of diving without the risk of locking open when fully opened.

Yet, despite this advancement, the age-old practice of opening the tank valve fully and then turning it back a quarter turn persists in some circles. Many divers continue to follow this tradition out of habit or because they were taught this method when first learning to dive. However, it's important to recognize that times have changed, and so have the recommendations regarding tank valve operation.

Today's best practice is to fully open the tank valve without turning it back a quarter turn. While either of those two tank valve positions will provide sufficient gas supply to allow you to breath, turning back a quarter turn is unnecessary. However, there are still considerations to keep in mind.

One such consideration is the potential for misinterpretation by dive guides or dive masters on boats. In the hustle and bustle of preparing for a dive, a fully opened tank valve might mistakenly be perceived as fully closed, leading to the valve being turned off instead of opened. This scenario happened to me just a few weeks ago. Fortunately, I always check my air just before jumping in the water as described below in the Pre-Dive Ritual.

As divers, we should take ownership and responsibility for all of our equipment and communicate our preferences to dive guides and dive masters. In a phone call I had with Dan Orr, former president of Divers Alert Network, and an expert in scuba diving safety, he said “what you do as part of your pre-dive preparation is to make sure that your breathing gas is on.” He went on to say, “if you’ve done that, then you should be the only one who touches your valve.” He further explained to me that he makes it clear to all the boat crew that he doesn’t want anyone touching his gear and if they do touch it, he wants to know what they did. Good advice that I know I will use going forward!

Pre-Dive Ritual

Additionally, adopting a pre-dive ritual can help ensure that your tank valve is fully open before entering the water. Taking a few breaths from both your primary and secondary regulators while monitoring the pressure gauge needle can alert you to any issues with tank valve operation. If you observe any fluctuations or irregularities in pressure, it's a sign that the tank valve may not be fully open, prompting you to address the issue before diving.

Conclusion

The debate over whether a scuba tank valve should be fully open or turned back a quarter turn is rooted in historical practices. While the latter method was once considered standard procedure, advancements in equipment design have rendered it unnecessary. Fully opening the tank valve is the recommended approach today, but divers should remain vigilant and proactive in ensuring the proper operation of their gear to enhance safety and enjoyment underwater.

Do you have any tank valve stories? Comment and share your thoughts.