If You Liked It, Then You Should Have Put a Ring on It:

The Complete Guide to Tank Valve O-Ring Replacement

By: Jesse Iacono

The common yoke tank valve o-ring may be the unsung hero of the diving equipment realm.  This humble piece of equipment is often overlooked or ignored, but it can make or break your dive. An o-ring may be the difference between exploring a beautiful reef with your buddy and remaining in the confines of the dive boat.  Learning the basics of o-ring inspection, maintenance, and replacement can help to ensure that you are prepared when your dive is the one at stake.

First, let’s talk about what a tank valve o-ring is and why it is so important.  When looking at the face of a yoke tank valve and the orifice of the corresponding regulator first stage, you will notice that both are made of metal and each has a ring shape molded into them; the valve has the ring depressed into the metal, while the regulator orifice has the ring protruding – these are designed as such so the regulator ring fits into the valve ring.  Unfortunately, metal on metal doesn’t hold a seal very well and will allow water and/or gas to move past if no additional seal is put in place between the two – here’s where the o-ring comes into play.  An o-ring is a circular piece of rubber or rubber-like compound that acts as a seal between the regulator orifice and the opening of the tank valve.  The o-ring will fit snugly into the depression in the valve face and the regulator’s protruding metal ring will fasten against it.  When an o-ring is properly fitted and installed, it allows gas to move easily from the tank to the regulator without escaping and prevents any water from entering the system.


When debris is trapped on or around the o-ring, the o-ring is damaged, the o-ring is broken, or the o-ring is missing, it can inconvenience and even endanger the diver.  If you attempt to use a system with the o-ring missing, you will know right away. Gas will quickly rush past the regulator and make a loud hissing sound – there will be no entering the water if one is not put in place.  For all of the other scenarios, they will typically present themselves as a hissing sound on the surface and a stream of small bubbles underwater; each of these will vary in degree based on the disruption of the o-ring.  While some may deem the small stream of escaping gas insignificant, it is an indication of a problem that should be fixed before entering the water.  Remember, we are trained from the start to avoid diving on equipment that is malfunctioning.  The danger here is that the problem will only get worse; the leak can be exacerbated due to increased ambient pressure, movement or bumping of the first stage while connected to the tank, or continued wear and pressurization on the o-ring.  At best, you are looking at some degree of gas leakage from your system and, at worst, you can encounter complete o-ring failure resulting in catastrophic gas loss.

Next, let’s examine where the breakdown may begin.  For most, this boils down to simple unfamiliarity with their equipment; this misunderstanding can stem from lack of appropriate training, interaction with other divers, and/or the natural degradation of skills and knowledge over time.  Consider your open water course: your instructor likely mentioned the importance of an o-ring and that it should be replaced if damaged or malfunctioning, but they may have lacked the time and resources to have every student in the class remove a deteriorated o-ring and replace it with a new one.  Think about how many times you have noticed a stream of bubbles coming from another diver’s equipment underwater and failed or forgotten to mention it to them after the dive. Think also of how many times you heard the small hiss sound coming from a diver’s setup and heard someone say it was nothing to worry about or would only amount to a breath or two over the course of a dive.  When we consider things that we do not fully understand, we can sometimes shy away and stay with what is familiar.  This can cause us to normalize practices such has getting in the water with malfunctioning equipment, writing it off as “no big deal.” These types of interactions are all too common but can be easily corrected with a little bit of education and practice.

Finally, let’s get to the steps for inspection and replacement!


  1. Angle the valve face into the sunlight or use an artificial source of light to ensure clear viewing of the o-ring. This will make it much easier to identify any debris or damage.
  2. Verify that an o-ring is actually present in the tank valve.
  3. Examine the o-ring for any debris or damage that may be present. Keep an eye out for shredding, cuts, cracks, punctures, rot, complete breaks, or other inconsistencies.
  4. If damage is encountered, move on to Removal.
  5. If no damage is encountered, attach the regulator to the valve appropriately, slowly turn on the gas, and listen for any hissing sounds.
    • If hissing sounds are encountered, inspect again or move on to Removal.
    • If the system is secure and no hissing sounds are encountered, go diving!



  1. Secure a tool for removing the o-ring. Typically, a soft metal pick designed specifically for removing o-rings will work best.  If not available, other relatively soft, thin pointed objects can work.
  2. Use the tool to remove the o-ring from the valve face. Depending on the condition of the o-ring, this may be something that happens very easily or presents some difficulty.
    • Once removed, the faulty o-ring will be discarded so don’t worry about damaging it any further. A considerable amount of effort may be required in some situations.  Please do, however, be careful to protect the surrounding metal that holds the o-ring.  While the discarded o-ring can tolerate a bit of rough housing, you will want to avoid adding unnecessary scratches or other damage to the valve itself.
  3. Discard the o-ring that was just removed.
  4. Look over the valve face for any debris, remaining pieces of the o-ring, or damage to the valve. If clear, move on to Replacement.Oring



  1. Acquire a new, proper-fitting o-ring. O-rings come in many sizes and thicknesses and, while many yoke valves can tolerate the same o-ring, some manufacturers will have a specific size that will fit and operate best.  For this reason, it is recommended to have several sizes included in your personal save-a-dive kit.
    • To quickly check if your o-ring is the appropriate size, line it up with the area that it will be secured into. If it matches the shape exactly, then it will likely be a good fit. If it is smaller or larger, then it may not fit appropriately. Due to varying sizes and thicknesses, sometimes the only true way to know if the o-ring will match is to insert it into position and see how it fits.
  2. Press the o-ring into place as much as possible using your fingers. A tool may be necessary to secure the o-ring fully into place.
  3. Secure a tool for pushing the rest of the o-ring into place. It should be something relatively soft and blunt.  The back side of the o-ring pick will work great, but in a pinch you can use a chopstick, the back of a pen, the blunt part of a car key, etc.  Anything too sharp or abrasive will cause damage to the soft o-ring.
  4. As you push the o-ring into place, it may bunch up, fold, or protrude in places; try your best to evenly distribute the o-ring and avoid unnecessary force. Continue the process until the o-ring sits securely in place with no protrusions.
  5. Once the o-ring is installed, attach the regulator to the valve appropriately; this will also evenly push the o-ring into place. Slowly turn on the gas and listen for any hissing sounds.
    • If hissing sounds are encountered, return to Inspection.
    • If the system is secure and no hissing sounds are encountered, go diving!

TankValve    TankValve

As with any scuba-related activity, always act within your comfort and training.  Practice and preparation are your best allies when approaching any type of new situation.  Go to your local dive shop and purchase a personal stock of o-rings as well as the basic tools needed to remove and replace them.  Practice the process a couple times either in the shop (with their permission, of course) or on your personal equipment at home.  If you still don’t feel confident in your ability, meet up with an instructor to show you the way, or ask a dive professional for help if encountered on the dive boat/at the dive site.  If you want to become a real hotshot of dive equipment, then talk with your instructor about enlisting in their next Equipment Specialist course.  Enjoy your newfound knowledge and keep an eye out for our next guide.  Use the comments section below to tell us about your relevant o-ring experiences and what other guides you would like to see in the future!

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