Douglas Ward
Contributor
I agree
Fatality at Jersey Island
- Thread starter DandyDon
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
Hollis has an opportunity to publish a Safety Notice regarding proper assembly of the DSV. It's so easy to detect the error even as a bystander from 20 feet away on a dive boat *if* you know that exposed threads on the DSV are the hallmark of an assembly error.
I notice several Hollis screen names in the "Thread Information" browsing the thread. I bet they're working on a notice as we speak.
I notice several Hollis screen names in the "Thread Information" browsing the thread. I bet they're working on a notice as we speak.
Wookie
Proud to be a Chaos Muppet
Staff member
ScubaBoard Business Sponsor
ScubaBoard Supporter
Scuba Instructor
At the end of the day, the rebreather that Ms Smith was using was non-compliant with the specs. It was one of 8 such units. Hollis changed the design so that newer units are manufactured in compliance. Highwing tested his Hollis P2 in the bathtub with no pants and a rubber ducky (I presume) and found that the unit passes a positive and negative to his satisfaction, but not to the specification provided by the manufacturer, and doesn't pass the stereo test at all (I don't even know what a stereo test is), therefore, anyone pre-dive testing that particular unit would catch that the unit is not assembled correctly. Anyone paying attention will see exposed threads on the DSV. What more do you want? A tragedy resulted in a better design.
gianaameri
Contributor
- Messages
- 793
- Reaction score
- 162
A Safety Notice is a step in the right direction.
The product would remain non-conformant to the required standard for Hollis to sell the product in the EU - that is Hollis loses a big market.
Hollis or its U.S. Distributor (say DivegearExpress, one of the best) would be able to sell it to an individual from the U.S., such individual becoming the "Importer," but then the individual would not be able to on-sell it to another EU person.
It is commercially limiting, to say the least.
For the 2 pence or 3 cents it costs to roll-out a fix, they should be working on a solution, from a commercial perspective, which actually makes the rebreather safer or in any event better.
---------- Post added December 3rd, 2014 at 01:15 PM ----------
Thing is, the rebreather can still be dangerously assembled and if used liked that (i.e. by human error blablablablablabla...) kill again.
Not exactly sure the fix is good enough.
Maybe it is, maybe it is not.
I cannot be the judge of that.
Guess HIGHwing can issue a Certificate to attest the unit satisfies the requirements of EN14143 as published/attested by him on Scubaboard and it is good do go!
descent
Contributor
Wookie -
Imagine you have a four foot piece of garden hose. Both ends of this garden hose are open, making it essentially a long flexible straw. Now drill a small hole at the mid-point of the hose and affix a mouthpiece to the hole you drilled. I'll now ask you to imagine breathing through the drilled hole. As you inhale and exhale through the mouthpiece air will enter both sides of the hose and exit both sides of the hose (presumably equally for this discussion).
This is not a circuit, and does not represent how a rebreather is supposed to work. The stereo test proves that breathing gas can only move one direction.
Let's modify our imaginary length of hose with two simple one-way valves , i.e. the mushroom valves, or perhaps some call them check valves. The purpose of these valves (when properly installed) is to force the direction of gas to go only one way, in a circuit, if you will.
We'll now install a one-way valve to the left of the mouthpiece that opens only when the user inhales. We'll install a second one-way valve to the right of the mouthpiece that only opens when you exhale. What we have now is a hose connected to the mouthpiece that can only inhale from the left side and exhale from the right. It's the beginning of a circuit.
The stereo test for most manufacturers asks the diver to place the palm of their hand over the inhallation hose and prove that breathing gas is not bypassing the exhallation one-way valve. To complete the test you'll cover the exhale side and try to exhale verifying the inhale valve stays closed. If this works, you've proved that the valves are installed, they are working, and that you are breathing in a circuit. (Individual testing procedures vary).
In the accident victim's case both valves were to the right of the diver facing each other blocking the circuit and turning the machine into a linear breathing apparatus. By doing this, nothing forces breathing gas into the scrubber in any meaningful way and she was essentially diving a very fancy plastic bag.
Imagine you have a four foot piece of garden hose. Both ends of this garden hose are open, making it essentially a long flexible straw. Now drill a small hole at the mid-point of the hose and affix a mouthpiece to the hole you drilled. I'll now ask you to imagine breathing through the drilled hole. As you inhale and exhale through the mouthpiece air will enter both sides of the hose and exit both sides of the hose (presumably equally for this discussion).
This is not a circuit, and does not represent how a rebreather is supposed to work. The stereo test proves that breathing gas can only move one direction.
Let's modify our imaginary length of hose with two simple one-way valves , i.e. the mushroom valves, or perhaps some call them check valves. The purpose of these valves (when properly installed) is to force the direction of gas to go only one way, in a circuit, if you will.
We'll now install a one-way valve to the left of the mouthpiece that opens only when the user inhales. We'll install a second one-way valve to the right of the mouthpiece that only opens when you exhale. What we have now is a hose connected to the mouthpiece that can only inhale from the left side and exhale from the right. It's the beginning of a circuit.
The stereo test for most manufacturers asks the diver to place the palm of their hand over the inhallation hose and prove that breathing gas is not bypassing the exhallation one-way valve. To complete the test you'll cover the exhale side and try to exhale verifying the inhale valve stays closed. If this works, you've proved that the valves are installed, they are working, and that you are breathing in a circuit. (Individual testing procedures vary).
In the accident victim's case both valves were to the right of the diver facing each other blocking the circuit and turning the machine into a linear breathing apparatus. By doing this, nothing forces breathing gas into the scrubber in any meaningful way and she was essentially diving a very fancy plastic bag.
The thread already exists: http://www.scubaboard.com/forums/re...al-safety-improvements-rebreather-design.html
Dr. Lecter
Contributor
WT
? If true, this incident has officially gone off into bizzaro land. Can you source the info or is it something you cannot yet disclose?On the one hand, diving a fully assembled CCR that you didn't build is up there on the list of what I'd call insane: among other reasons, you cannot do the stereo check, which confirms the hearts of your one-way gas flow are actually working right, with the loop assembled on the unit. On the other hand, it would make this much, much more tragic than it already is...if someone else has to kick themselves for what happened.
A ScubaBoard Staff Message...
I'm looking at the total situation rather than just a bunch of parts and pieces attached with fittings. Let's look at how we got to the accident dive. Husband and Wife purchase P2s and inital training. They complete the class together allegedly achieving certification. On the fatal dive, Wife misses a half dozen cues the rebreather is assembled incorrectly?
Based on my own "testing" last night, I have admitted I can see how this could happen with an inexperience user (read back if you want the details) - but only if they are presented a unit incorrectly assembled to begin with.
If someone else built the rig, she is certainly omitting the stereo test, but she can reasonably validate most everything else. Her primary focus with a built rig is the unit maintains SP, she can flush PO2 up, she can flush PO2 down, she can breathe normally, and complete a pre-breathe. Last night I stumbled on this conclusion after trying to build my P2 in all sorts of crazy-ass ways. But when I assembled the P2 the exact way she did, she can "complete" the checklists, with subtle errors (actually failures).
In my mind, the only way she misses the mountain of cues available to her is if she didn't build the rig and didn't have all the information in the first place.
Similar threads
