Oceanic Dry Valve Technology

I'm looking at the Delta4 with FDX-10 first stage as my new regulator for this season. However, I'm really not happy about Oceanic's DVT -- Dry Valve Technology.
My dealer received a cutaway cross-section of the DVT mechanism, which basically consists of a bullet-shaped piece of red plastic attached to a spring. Interesting concept, and will probably save a few people from having to replace the guts of their first stage. But I think there is a design flaw, and I'd love to hear feedback from someone better informed.
What I can't understand about this mechanism is why the "stopper" seats against the rather pointy-edged metal of the first stage (not represented well in the diagram, but you get the idea), rather than an o-ring. The plastic of the stopper is fairly hard, but in order for it to effectively stop water from entering the first stage, the spring has to exert some pressure, pushing the stopper into those metal points. Without a doubt, this plastic piece will begin to wear out over time.
The issue, however, is not the fact that the part will wear out. (Frankly, I don't care if it wears out, and would rather it was optional with purchase.) The issue is, if you look at the design, all the little scrapings that are bound to happen when the stopper seats against the metal have to go somewhere, and based on what I can see, that "somewhere" is "inside the first stage."
So a few things come to mind. First, are you going to be breathing these bits of plastic? What is the stopper made from?
Second, when this "erosion" process inevitably begins, will the fine bits of material within the first stage create an increased flash hazard with high FO2 / PO2?
Third, you won't be able to see the filter, and so if you get moisture or other contaminant from a cylinder, you won't have a good visual means to identify the problem.
Would love to hear from greater minds on this matter. Doug Krause, are you out there too?
-Andrew

Hmmm, never thought about this but it seems that you have a good point. If all else fails why don't you take out the "bullet"? From what I have seen of them it shouldn't be that hard to do.

Well, there is really not much spring pressure, so I really doubt there will be any "bits of plastic" coming off. I've had a plastic cell phone, computer keyboard, etc for a long period of time... and all the bits are still there...

And, even if it did, the filter sits behind the DVT, so it would catch everything.

As far as not seeing corrosion... it will reduce it so much by stopping the occasional accidental spill from the cap, off your wetsuit sleeve, the clumsy divemaster... you really should not get much if any. And with your annual inspection and rebuild every other year... that would catch any potential problem that could crop up.

Do I think the DVT is necessary?? No. Is it really kinda' neat... and will it help some people get more life out of their gear if they are not the overly careful kind?? Yes.

So if you want to get the reg because of it... I can understand that. But the Delta IV is a great reg, and even if you don't care about the DVT, it would still be a very nice reg to own. Everyone we've sold them to has been very happy with the performance.

A relatively soft material seating against a metal orifice is very typical in first stage valves. Whether a diaphragm or piston, this type of valve is likely used - and is exposed to much higher pressures and spring forces, and sharper metal sealing surfaces. The DVT "bullet" or stopper is made from the same material as used in some of our high pressure seats.

fashionablylate:

I'm looking at the Delta4 with FDX-10 first stage as my new regulator for this season. However, I'm really not happy about Oceanic's DVT -- Dry Valve Technology.
My dealer received a cutaway cross-section of the DVT mechanism, which basically consists of a bullet-shaped piece of red plastic attached to a spring. Interesting concept, and will probably save a few people from having to replace the guts of their first stage. But I think there is a design flaw, and I'd love to hear feedback from someone better informed.
What I can't understand about this mechanism is why the "stopper" seats against the rather pointy-edged metal of the first stage (not represented well in the diagram, but you get the idea), rather than an o-ring. The plastic of the stopper is fairly hard, but in order for it to effectively stop water from entering the first stage, the spring has to exert some pressure, pushing the stopper into those metal points. Without a doubt, this plastic piece will begin to wear out over time.
The issue, however, is not the fact that the part will wear out. (Frankly, I don't care if it wears out, and would rather it was optional with purchase.) The issue is, if you look at the design, all the little scrapings that are bound to happen when the stopper seats against the metal have to go somewhere, and based on what I can see, that "somewhere" is "inside the first stage."
So a few things come to mind. First, are you going to be breathing these bits of plastic? What is the stopper made from?
Second, when this "erosion" process inevitably begins, will the fine bits of material within the first stage create an increased flash hazard with high FO2 / PO2?
Third, you won't be able to see the filter, and so if you get moisture or other contaminant from a cylinder, you won't have a good visual means to identify the problem.
Would love to hear from greater minds on this matter. Doug Krause, are you out there too?
-Andrew

Click to expand...

As Doug pointed out the material used in the DVT bullet is not new, only the red dye is. I do not foresee pieces of the bullet being worn away. When the DVT is in use off the tank there is very little pressure exerted on the bullet from the spring and any air left in the reg, just enough to keep water out. The same material used in the HP seat stands up to 3000+ psi in the PX3 with thousands of cycles againts a stainless piston and it doesn't cut away chunks of the seat.

If the DVT is a true concern for you it is possible to use a non DVT yoke retaining nut assembly from the CDX5. Your Oceanic dealer can get the parts and install for you.

Best,

Chris

I currently own a Delta 3 w/ CDX5 DIN. I like Oceanic's products. I want to point out that, while I have brought this up as a question, it was not a factor in my purchasing decision. I ordered a Delta 4 with an FDX10 yesterday. However, I think that those who have responded are not quite understanding what I am questioning.

When looking at the design of the DVT, it is impossible to suggest that the stopper is not a "wear" part. Over time, it will wear out by virtue of repeatedly coming into contact with a surface harder than itself. I'm not talking about huge gouges of material. I'm talking about erosion on a molecular level. I'm guessing Oceanic is aware of this potential, and I'm also guessing they have a replacement part number for it so it can be replaced when it wears out.

While I really could care less about the DVT waterproofing mechanism, I am concerned about this ultra-fine layer of eroded material collecting somewhere within the first stage. The reason I'm concerned about this is because if I later opt to use this reg for a deco bottle, I don't know how this material will be affected by higher FO2 / PO2. As a solid piece, it may not be affected at all. But as super-fine dust...it could be a different story.

Initially, my thought was to use this reg for a deco bottle and replace the yoke with a DIN to avoid the DVT question marks, but now I see that Oceanic is developing a DIN version of DVT. Evidently Oceanic is more confident (or proud) of its technology that perhaps it ought to be. As Cerich mentioned, the CDX5 can be used in its place, but the CDX5 is years old -- is DVT the only improvement in the FDX10? What other benefits am I sacrificing by going with a non-DVT first stage?

Additionally, no one has really addressed the issue of the invisibility of the filter in the first stage. The filter is really the diver's visual indicator that something bad is lurking in their cylinder. As Larry pointed out, this will be noticed during annual service, but that means you could potentially be flirting with lipoid pneumonia or other problems from bad fills or cylinder corrosion for most of the year, and never know it because you've no visual clue. When we teach scuba, we advise our students to check the filter for signs of contamination. Now we'll have to add an "unless you have a DVT first stage, in which case...keep your fingers crossed" clause to our curriculum. Oceanic is making it difficult for me to support their product into the classroom, because I simply don't believe the benefits of DVT outweigh the risks as it relates to the first stage filter.

-Andrew

Hi Andrew,

I want to hit each of your points so I'm going to copy your message and break in with my reply

"I currently own a Delta 3 w/ CDX5 DIN. I like Oceanic's products. I want to point out that, while I have brought this up as a question, it was not a factor in my purchasing decision. I ordered a Delta 4 with an FDX10 yesterday. However, I think that those who have responded are not quite understanding what I am questioning.

When looking at the design of the DVT, it is impossible to suggest that the stopper is not a "wear" part. Over time, it will wear out by virtue of repeatedly coming into contact with a surface harder than itself. I'm not talking about huge gouges of material. I'm talking about erosion on a molecular level. I'm guessing Oceanic is aware of this potential, and I'm also guessing they have a replacement part number for it so it can be replaced when it wears out.

<<<<The DVT is an inspect at every service part. As I pointed out above the same material is used in endless cycles at 3000+ psi in other applications/regulators we offer. The cycles on the DVT bullet are less (once each time it goes on the tank vs. thousands of times a dive when used as a HP seat), the harder material (chrome plated brass) is also softer than Stainless and the pressure is much less (like 10 psi or so- correct me if I'm wrong Doug). The wear on the bullet is not a concern at all. We have "replacement" parts for every part, nothing special on the DVT bullet here>>>>

While I really could care less about the DVT waterproofing mechanism, I am concerned about this ultra-fine layer of eroded material collecting somewhere within the first stage. The reason I'm concerned about this is because if I later opt to use this reg for a deco bottle, I don't know how this material will be affected by higher FO2 / PO2. As a solid piece, it may not be affected at all. But as super-fine dust...it could be a different story.

<<<< I am not worried at all about there being an ultra fine layer of eroded material. You wouldn't be able to use the reg enough between service and inspection for this to happen, even if it was 24/7. As for on a deco bottle, well our regs are for up to 40% Nitrox. We had a dedicated oxygen reg that didn't sell very well due to price and features, most divers would choose a less expensive route. As a manf. there are serious liablity issues with making a reg for 100% O2 that is why the high cost, especially when you consider there is no real standard in North America on this issue. There are in Europe and it is causing the industry a fit over there.

As a Tech Instructor now, not as a manf. rep., for a deco reg I teach that you have it cleaned for oxygen service and dedicate the reg to deco only use. I also recomend DIN so as of now that means no DVT with the Delta 4 so no issue.>>>>

Initially, my thought was to use this reg for a deco bottle and replace the yoke with a DIN to avoid the DVT question marks, but now I see that Oceanic is developing a DIN version of DVT. Evidently Oceanic is more confident (or proud) of its technology that perhaps it ought to be. As Cerich mentioned, the CDX5 can be used in its place, but the CDX5 is years old -- is DVT the only improvement in the FDX10? What other benefits am I sacrificing by going with a non-DVT first stage?


<<< I never said to use the CDX5 in its place, I said to use the same DIN fitting the CDX5 uses. It fits. As of right now there is no DVT DIN fitting for Oceanic. I discussed this today with my Boss(and Dougs) and we have no timeline on when DVT in a DIN will be available. There are issues that have nothing to do with how proud we are or engineering that has set the DIN DVT on the backburner.
The FDX10 is not only DVT, it is very high flow and better intermediate Pressure control, overall a much better regulator even without DVT>>>>

Additionally, no one has really addressed the issue of the invisibility of the filter in the first stage. The filter is really the diver's visual indicator that something bad is lurking in their cylinder. As Larry pointed out, this will be noticed during annual service, but that means you could potentially be flirting with lipoid pneumonia or other problems from bad fills or cylinder corrosion for most of the year, and never know it because you've no visual clue. When we teach scuba, we advise our students to check the filter for signs of contamination. Now we'll have to add an "unless you have a DVT first stage, in which case...keep your fingers crossed" clause to our curriculum. Oceanic is making it difficult for me to support their product into the classroom, because I simply don't believe the benefits of DVT outweigh the risks as it relates to the first stage filter.

<<<<I agree we have been teaching to look at the filter and with DVT it is not possible for the average user. Cylinder corrosion will show on the bottom of the filter not the top so the user won't see it anyhow, oil contamination will probably/possibly show on the bullet. These risks are very small but real, so I don't want to dismiss out of hand what you point out. However I feel you may be over stating the hazards. involved. >>>>>

Let me again state that I am very happy with Oceanic products, and have been using them for years. I recently bought a Delta 4 with an FDX-10 DVT first stage for my personal use, and will be using it regularly this dive season.
The conversation is not meant to discredit the product or the company, but rather to initiate an academic discussion to help my own understanding of the product and the technologies it makes use of. In many such conversations, when discussing the minutae, we are essentially magnifying (or making issue about) something excruciatingly tiny, but it is important to note that the conversation in this thread is based almost entirely on hypothetical circumstances that will not apply to an actual diving condition.

Thank you, cerich, for really taking the time to explain the various components.

I appreciate your insight into the infrequency by which the bullet will come into contact with the first stage, and how that staggeringly small number renders my concern about first-stage material buildup pointless.

I greatly appreciate your patience, and for correcting my earlier misunderstanding related to the CDX5 first stage DIN adapter. That is very helpful advice, and if I should decide to dedicate this reg to higher O2 service, I will very definitely be taking your advice.

-Andrew

I have a different concern with the DVT technology. I purchased an Oceanic Delta 4 FDX-10 for my wife as soon as they hit the market. We went to Cozumel a short time later. The regulator performed great with the exception that we had a loud whistling noise coming from the first stage. I am a technician for the shop where I bought it. So I did some tests on the reg. When I took out the DVT it did not make any noise. Put it back and the whistling continued. When I talked to Oceanic (Ron really took care of me)they promptly took care of the issue by sending me a CDX-5 (which has performed flawlessly). I would like to know if this has been an issue that Oceanic has noticed on a wide scale or has this just happened with a few regs? I have absolute confidence in the performence of the FDX-10 but if you have ever been under water for an extended period of time with a whistling reg it is very annoying.

Thanks

Gillty

Gill,
When this reg first came out, we encountered exactly the same problem that you are describing. It boiled down to a design problem; something about the pathway for airflow is causing a harmonic.
We sent the regulators back to Oceanic, and they replaced them.