Valve Isolation Protocol

Before we start let’s look at the likelihood of experiencing a failure in the first place and think where the most likely situation it would happen is; in open water or in an overhead/cave environment? In an overhead environment there are plenty of obstacles that may damage a regulator or the manifold bridge. The most likely probability of this happening is coming into contact with the ceiling during a zero visibility situation where constant contact with a line is necessary it requires the use of one hand. It is therefore necessary to learn the proper procedure in order to accomplish this in the fastest most accurate manner.

In technical and cave diving we don’t guess the direction of our exit, we know!! We don’t estimate what our gas requirements are, we plan it based from our known RMV. So why would we act any differently with our emergency protocols. Take for example the statement; “Isolate the manifold and feel for bubbles, try to determine if the leak is coming from the right side or left side and isolate it”. To me this is simply guess-work and guess-work is not for technical cave divers.

If we look at a basic Hogarthian configuration we can determine that there are really only four failure points that we would need to isolate thus giving us an easy isolation equation.
First: The right first stage and assembly, this includes all the attached hoses and primary second stage.
Second: The left first stage assembly with all its hoses, alternate second stage and SPG.
Third and Fourth: The right and the left valve assemblies, each valve assembly includes the O-rings on its side of the isolation manifold, the valve handles, tank O-rings and burst disks.
We may also determine that in the event of a valve failure from either side we will lose approximately half of our remaining gas and in the event of a first stage failure we will lose redundancy; in either event the dive must be terminated.

As far as resolution protocol is concerned we need to determine where a gas hemorrhage is happening and where to isolate the problem as fast as possible. We also need to be able to do this while maintaining contact with a line, buoy, stage cylinder, descent line, unconscious buddy or whatever else we may be holding on to.

We can do this through a very simple process of elimination but before we proceed you must first understand some of the reasoning behind a basic Hogarthian configuration.
You must first understand that the reason the long hose is on the right first stage is that the left valve has the potential for “accidental roll-off” (the process of the valve handle rolling shut due to the direction of travel when it comes in contact with the celling of an overhead environment).
This is also the reason we have the (SPG) and alternate second stage on the left first stage in order that we can monitor any change or lack of change in gauge pressure thus giving us prior warning to the possibility the valve has in fact rolled off.
In the event we suspect a roll off or see no change in gauge pressure, we simply purge the alternate second stage and watch the SPG, if it happened that the isolation manifold was closed we would see no change in gauge pressure whereas if there is in fact a roll off we will see an immediate drop in gauge pressure. Either way a simple purge of our alternate second stage delivers the correct answer. No needs for guess work therefore ensuring you turn the appropriate valve the correct way.

We always donate the primary regulator in order to provide a functional second stage to a diver in need because we know it is working and has not rolled off; we were just breathing from it.
The primary second stage is on a 2 meter or 7 foot long hose to facilitate exiting through a restriction while diving in a single file. The long hose is tucked into the belt and routed around the neck for streamlining and ease of deployment.

The alternate second stage is secured on a bungee cord around our neck so we always know where to find it. Since we are the ones having to use it there is no guessing as to where it may have gone.

Using the correct lengths for hoses almost eliminates the possibility of dropping your primary second stage into the hose loop for the alternate second stage and reduces the possibility of entangling the long hose as well as decreases drag and vibration in current.

An SPG running down your arm and attached to your wrist keeps it easy to see, easy to read and out of the way of stage cylinders, you can watch it while isolating the manifold to help determine which side is hemorrhaging and do so without having to disconnect it from a D ring or while maintaining contact with a line.

Hoses are routed in a manner that eliminates “pinch” or the possibility to have your breathing hoses kinked to the point they cut off or reduce the gas supply when either deployed or by the inflated wing.
And lastly valves are opened all the way without any roll back so there is no confusion as to which way a valve must be turned to shut it.

We must also regularly perform what I refer to as “Reality checks”. A reality check is a constant vigilance to be performed before and after passing any restriction, before making any jump or at any point of complex navigation, before responding to an “OK” and any time after you come in contact with the celling as well as during “bump and go” zero visibility exits after every placement while waiting for your buddy.
A reality check is a simple verification of your left valve to make sure it is still open. A sweep of equipment checking to feel if anything has come loose or is out of place and lastly a check of your Time, Air and Depth or (T.A.D.) This prevents a diver from ever accidently ever having a non-functional second stage in the event of a gas sharing situation or valve resolution procedure due to roll-off. This also trains divers to be vigilant and aware of their configuration, no-deco or decompression limits and run times, turn pressures and gas consumption and lastly depth limits. It also prevents accidental entanglements due to dangling equipment, having to turn a dive during a jump or the minute you finish one. It prevents the passing of restrictions with entanglement hazards or a non-functional alternate second stage.

Now let’s get to a resolution procedure. First we must know and understand a few basic principles of equipment.
One: if a valve is turned off it stops the flow to the attached first stage and everything attached to that first stage therefore if the valve is closed and the bubbles don’t stop it is not the fault of that valves first stage or any of the connected hoses.
Two: if it is NOT the fault of a first stage regulator assembly and the manifold is closed you will only lose most of the gas in the affected cylinder.
Three: the best way to determine which cylinder is losing gas is while the manifold is isolated to look at your SPG.
Four: In the event we are losing gas it is better to start an isolation procedure and find the problem using a process of elimination than to guess what the problem is while continuing to lose gas.
Five: according to “Hicks Principle” the fewer procedures we have to respond to any given set of emergencies the faster we respond. The more procedures we have to respond to any given emergency the longer it takes us to make the choice and therefor the time delay is greatly increased or simply put; when something happens do the same thing every time, it will speed up your reaction and therefore the resolution.
Six: only in the event of a complete light failure, your primary and both back-ups along with those of your partner is it not possible to see an SPG when illuminated, so keep it illuminated. (I say this with a lot of experience of diving in the most extreme silt outs. I have never, not been able to see my SPG)

The Process:

First: switch hands so the left hand is holding whatever it needs to be it the line or whatever. We are going to use the right hand and only the right hand to both open and close the isolation manifold. Due to the mirror effect the right and left hands think the opposite is the same thus closed is open and open is closed in either given hand and if there is any discrepancy there is a chance it is turned the wrong way. Also if the SPG is on the left hand you can watch it to see if there is any change in gauge pressure after the isolation manifold has been closed, to earlier determine which side is losing gas, you can also do this while maintaining contact with a line.

Two: with the right hand close the isolation manifold first, this does not shut down the breathable air source to the diver while the manifold is being closed and saves half of the remaining gas. This also allows a diver to signal to his team mates while shutting the isolation manifold at the same time if the torch is held in the left hand.

Three: immediately with the same hand shut down the right valve. As the right post is the one being used it is statically more likely to experience a failure than the left.

Four: immediately with the right hand find the alternate air source and place it in your mouth. It is un-necessary to use a hand to remove a regulator from your mouth when you are more than capable of spitting it out. It is much more appropriate to have the regulator ready to go into your mouth in your hand; this avoids confusion as to which one you just dropped. Also use the purge method to clear the water anytime a regulator is going into your mouth. Blast purging may be the last air you have; do you really want to waste it getting water out of a second stage regulator!

Five: listen for a second, did the hemorrhage stop? If not it was NOT the right first stage assembly and it is necessary to open the valve before continuing in order to maintain a continuous source of breathing gas. If a valve sticks and you shut the other one you are going to be in a lot of trouble.

Six: after re-opening the right post switch hands; you are now done with the right hand. Everything was accomplished with one hand and no time was wasted with un-necessary hand switches.

Seven: with the left hand shut the left valve.

Eight: with the left hand immediately find back the long hose regulator and replace it in your mouth. Remember to spit the regulator out of your mouth not to use your hand as it prevents confusion and don’t forget to purge rather than take the chance of wasting your last breath.

Nine: listen for a second, did the hemorrhage stop? If not it was NOT the left first stage assembly and it is necessary to re-open the valve as we now know that there is a failure in one of the valve assemblies and we will lose half of our gas. Now we need to know which half that will be. In order to maximize the amount of gas remaining we want to breathe from the hemorrhaging cylinder for as long as the gas lasts before switching to the isolated cylinder.

Ten: in order to accurately determine which cylinder is losing gas we need a working SPG therefore we need to re-open the left valve and examine the SPG for a drop in gauge pressure. If there is a drop in gauge pressure it is the left cylinder and we breathe from the alternate second stage. If there is NO drop in gauge pressure we know it is the right cylinder and breathe from the primary second stage regulator on the long hose.

In any event of a problem, loss of communication or equipment failure the dive must be cancelled and the divers must return to the surface. The diver that is experiencing the failure or problem is the first diver to exit. This not only puts the diver at ease but also makes a gas exchange easier in the event they did in fact have an air sharing situation as the diver would already be in the correct position for the proper routing of the hoses and there is no need to change places.

It may seem like a lot to do but it is a very simple process that eliminates any guess work and if practiced this can easily be accomplished in less than 40 seconds with minimal gas loss or delay.

Valve isolation drill simplified:

  1. Shut Isolation Manifold
  2. Shut Right Valve
  3. Switch to Bailout Regulator and listen for bubbles
  4. Re-Open Right Post
  5. Switch hands on line
  6. Shut Left Post
  7. Switch to Primary Regulator and listen for bubbles
  8. Re-Open Left post
  9. Examine SPG for change
  10. Switch hands and Re-Open the isolation manifold

In the event it is a real situation:

  1. Determine which side is losing gas and breathe from the affected cylinder
  2. When empty switch to the non-affected cylinder and continue exit

Posted 18/07/2012 by Sirius Diving