HELPFUL TIPS
BCD problems & maintenance   2/4/16
BCD's are often neglected until they have problems.  Aside from a sticking inflator, which can be life-threatening in the worst case, a leaky aircell may be a simple fix or signal the end of its useful life.  In any case, your BCD should be rinsed well inside and out after use, almost fully inflated for drying in the shade, and stored in a dry ventilated area to prevent mold.  Annual service of the inflator or alternate air source/inflator combo is, in my opinion, more important than regulator service because a sticking inflator can lead to uncontrolled ascent.

A common problem for shore divers are sand-choked dump valves, which are easily unscrewed for cleaning, as long as the cap is not cross-threaded.  Dump valve springs may rust and break causing a big leak.

A common problem I see with older BCD's (>5 years) is plastic fatigue.  In warm climates these new plastic elbow and dump valve fittings become brittle and shatter.  In most cases the broken part is a male threaded bulkhead welded to the aircell, but airway screw-on fittings and inflator bodies can also crack and fail.  If the manufacturer no long has replacement parts that BCD is no good.  Trade it in and upgrade to a new one.



Many users neglect rinsing the aircell's interior thoroughly.  Over time seawater within the aircell can become supersaturated and form large salt crystals.  In exceptional cases they can form a large crunchy mass.  Needless to say, these hard glass-like crystals can slice the aircell, but more often, tiny crystals grow within the aircell fabric, eventually creating pinhole leaks.  These leaks may be repaired in some instances using urethane adhesive or patching kits.  My policy is to not carry out such repairs, fix it yourself or uprgrade to a new one.
 
 
Freeflowing second stage    4/18/15
A freeflow is the condition when a regulator second stage delivers a high volume of gas when removed from the diver's mouth.  There are four situations which cause this, two of which are user error:

1.  Venturi control lever in the wrong position.
2.  Alternate air source improperly secured.
3.  Improper airway control when removing regulator from mouth.
4.  Stuck lever or contamination within second stage.
5.  First stage intermediate pressure exceeding normal specification (both second stages would shudder violently).

While cases 4 & 5 can only be addressed by a technician, the first three are common occurrences with inexperienced users or experienced users who don't understand design features of their equipment.  Scuba instructors and dive shop salepersons should point out these facts so the user has a positive experience.
1.  Venturi control levers
 
 
Damaged yoke retainer sealing surface    3/20/14
 
An often-overlooked part of your regulator first stage is the sealing surface that mates with the cylinder valve o-ring.  In heavily-used regulators this area eventually loses the ability to seal due to nicks and subsequent loss of chrome plating.  Typical damage is caused when the sealing surface accidentally hits the valve during setup/breakdown and corrosion occurs due to incomplete rinsing.  The yoke system is a tenuous connection - the actual sealing surface is only a couple of millimeters wide as is the metal-to-metal contact around it.  Any damage to the o-ring or yoke retainer flats cause the connection to leak to some degree, from a minor trickle of champagne bubbles that may be temporarily halted by rotating the first stage a bit (which shreds the valve o-ring), to a big leak upon pressurization that can't be stopped (especially with Pro-valves).  The flat sealing surface can also be warped by using the first stage as a handle while lifting the scuba unit, and especially when an unattended scuba unit falls over and the first stage hits the ground, resulting in an unstoppable leak.

The obvious solution to this is replacement of the yoke retainer, which must be done by a certified technician using a torque wrench, since improper installation may result in catastrophic first stage failure and personal injury.  Remember that any leak here may allow seawater to enter the first stage as indicated by green corrosion on the filter.  You should also inspect the cylinder valve o-ring for damage.  See the next section for more information.

Most modern regulators have replaceable yoke retainers in the $30-50 range.  Models without can only be fixed by replacing the main body, which is not economically feasible.  These include many Sherwood, US Divers Conshelf, and Mares MR12 first stages.  In these cases, a new first stage may cost nearly the same as having the damaged one repaired.
 
Keeping saltwater out of your regulator



There are several ways for salt water to enter your first stage. One is the result of a damaged cylinder valve outlet o-ring. When the o-ring where the cylinder valve and regulator first stage mate is damaged due to heavy use (especially rental tanks) a small amount of water can get drawn into the system while breathing. A telltale sign of such a leak includes hissing before the dive when air is turned on. Rotating the regulator may stop the leak, or not. Underwater this appears as a constant stream of fine bubbles behind your head and you'll probably be annoyed by the 'fizzing' sound.

This is usually a low-volume flood that corrodes the inlet filter. In worse cases it can flood the pressure gauge. In time, corrosion will cause first stage failure, namely a leaky second stage or octopus.

You can prevent this by inspecting the valve outlet o-ring before use, ideally at the dive shop because they should have o-rings, and replacing the o-ring if it isn't in perfect condition. Shops that really care may include a spare with the dust cap or Sherwood burst disc nut. Keep a few spares and a sharp tool to remove the old o-ring in your dive saver kit. If you own tanks, I recommend switching to urethane (cream-colored) o-rings. They are highly resistant to wear and last much longer. Trident R014-S for standard Thermos or Sherwood valves or R112-S for Pro-valves and DIN regulators.

 

 
Sand in the second stage causing freeflow

Keeping your alternate air source (octopus) secured near your chest is important to protect your gear and the environment, in addition to making it easily accessible in case of emergency. However there are situations when the best care does not keep sand out. In my case this happens after a dive at the Halona Blowhole, not to mention Rescue Diver training at Waimanalo. If you are unlucky, sand gets stuck to the regulator's low-pressure (LP) seat and causes a slight but persistent freeflow.

Aside from taking a few strong breaths or depressing the purge button a few times in hopes of clearing the LP seat, there's nothing that can be done to safely fix it while diving. In fact, turning off the gas supply and fully depressurizing your regulator while submerged will cause a catastrophic flood and ruin the pressure gauge. Therefore this can only be done out of the water. The following technique will allow freshwater to enter the system where it should not normally be, so I do not endorse it as a 'good practice'. However, if you are on a dive expedition without access to a trained scuba technician, this may solve your problem.

After diving keep the regulator mounted to the cylinder with gas supply turned off and depressurize the system. Fully submerge the leaky second stage in a container of freshwater or use a water hose to flush the second stage via the mouthpiece. Contrary to what you were taught in Openwater Diver class, depress the purge button a few times for one second intervals to allow a small amount of water to enter the system. Turn on gas supply and purge second stage several times, blowing out the water and hopefully the contaminant. This frequently solves the freeflow problem but there's a chance that sand is too deeply embedded into the LP seat, or the sealing surfaces have been damaged, requiring service or replacement. At that point the system must be tested and probably overhauled.

There are other methods to fix this problem but must only be done by a trained service technician to prevent damage, voiding your warranty, or personal injury.

If you are lax when it comes to after-dive cleaning, there's a good chance large salt crystals may form and corrode any metal parts or embed themselves on the LP seat. In this case I'll expect to see you sooner than later, so treat your regulator with proper care. Your life literally depends on it.

 
Content and images on this website are the property of Keoki Stender unless otherwise indicated.  Keoki's Scuba is not responisible for any personal or property damage or injury caused by any advice or services provided herein.  Scuba diving/snorkeling is a potentially hazardous activity and should only be attempted by qualified users in situations within their skill level and physical ability.  Your comments are welcome.