Isolation valves or full independent Doubles

[bamafan]

Is there a valve in the market where you can do the same isolation for sidemounts, but with a hose of course, don't know if it make sence to have one sounds kind of cucumbersome and maybe dangerus .

Yes there is and it is made by UTD. In my opinion it takes some of the advantages of sidemount and does away with them. It is also adding in failure points in my opinion. If you have calculated your gas reserves correctly (not breaking 1/3 rds in either tank) you should have enough gas to get out of a cave. Now decompression makes it more complicated but normally that is not done on backgas anyway.

I personally have about the same opinion of this thing as most have for the OMS slob knob.

UTD Z-Isolatable Manifold · UTD Scuba Diving

 

[AfterDark]

Remy, there are a lot of different reasons people use the configuration(s) they use, safety is usually the 1st however in some cases like mine isolation valves would put me in danger for the simple reason that I cannot reach the posts to operate the valves while mounted on my back; due to 2 rotator cuff operations my right arm has lost some range of motion and muscle; even if I did manage to reach it I may not be able to turn it. Some moves just don't happened when my arm is different positions.

However I want the safety and capacity of doubles, the trade-off is independent doubles which I'm comfortable with. During 44 years of diving I never had a regulator failure with my regulators. For many years I dove with only one regulator without problems. These days I'm more cautious and want redundancy when I solo or do deep diving. I had everything I needed to put together a ID kit so I did and have refined it with time. I use different size tanks from 50cuft LP to 94cuft LP depending on the dive. All my diving is OW ocean with little to no overhead; however there are dives where the boat traffic is so heavy I treat it like a hard overhead. The point is if my dive is within NDL as it usually is I can lose all the air in one tank and still make it back to the egress point or boat. It does limit my diving some but age is doing that anyway. I also like the fact I can carry one in each hand in and out of the LDS and also use them as singles.

From my POV equipment failure is much over blown, if gear is well maintained and serviced it will last a lifetime a fact I can attest to just by the gear I use some of which is 40+ years old and still hasn't failed.

 

[Remy B.]

Remy, there are a lot of different reasons people use the configuration(s) they use, safety is usually the 1st however in some cases like mine isolation valves would put me in danger for the simple reason that I cannot reach the posts to operate the valves while mounted on my back; due to 2 rotator cuff operations my right arm has lost some range of motion and muscle; even if I did manage to reach it I may not be able to turn it. Some moves just don't happened when my arm is different positions.

.

Good point I as well have difficulties trying to reach the valve Knob on the tank, or I just need to install them high enough and bounce my head to the 1st stage occasionally, still I can reach the center isolation valve knob but not sure if I can reach the ones on the tanks without feeling like someone had stick a piece of re-bar in my shoulders , will see once I get to the point to use back mounted doubles, thanks for bringing that up.

---------- Post added April 17th, 2015 at 05:08 PM ----------

Yes there is and it is made by UTD. It is also adding in failure points in my opinion.

I personally have about the same opinion of this thing as most have for the OMS slob knob.

UTD Z-Isolatable Manifold · UTD Scuba Diving

I agree with that

 

[wedivebc]

Thanks guys I'm more clear now, make all sence to have and isolator, I was looking at it the wrong way.

Please keep posting your opinions, it will bring more light to the thread and others that may have the same question as I did.

Is there a valve in the market where you can do the same isolation for sidemounts, but with a hose of course, don't know if it make sence to have one sounds kind of cucumbersome and maybe dangerus .

Unless you plan to continue your dive beyond the point a failure occurred independent doubles will never render you with insufficeint gas to exit the dive, even in an overhead where rule of thirds must be adhered to.

Since so many people are diving sidemount these days which is just another form of indepenent doubles I don't see the big deal whether they are on you back or at your side. The gas management is pretty much the same.

 

[Akimbo]

Failure mode analysis is a probabilities game and you have to assign the values to each risk factor. Unfortunately reliable data on failure frequency isn’t available. You can’t just count failure points either; you also have to consider the probability and severity of each failure.

The isolation manifold reflects a designed based on the highest probability of failure being one of the regulators. Therefore the increased failure potential of the additional manifold seals outweighs the risk of being able to connect your remaining gas to the still operable regulator —probably an excellent assumption for ice divers.

One engineering principal is known, though the relative failure numbers are highly variable and debatable. Static O-rings are more reliable than dynamic O-rings. Static O-ring sealing surfaces don’t move under pressure like seals between the regulator and valve or the valve to tank seal. Dynamic O-ring sealing surfaces move under pressure, like in your regulator and valve stems for example. However, the nature of the failure is equally important. Most failures are many more times likely to be a slow leak rather than a high-flow failure such as an O-ring blow out.

An isolation manifold does support the use of Progressive Equalization which is most useful when you are distracted, narc’ed, and/or in zero visibility.

IDs (Independent Double) are side-mount and travel friendly. I say travel friendly because you can bring your own back or sidemount hardware and adapt to the single cylinders available at remote sites. Using a bailout bottle (pony) functions as IDs, it just happens that the primary is usually larger but the failure-mode principles are the same.

I no-doubt forgot a bunch of factors but hopefully it will help you develop your own decision matrix.

 

[Peter69_56]

I think too many people get stuck on trying to prove one method is better than the other or the one you must use.

For me I adapt to the need and the situation. If you go to a site and they have no manifolded doubles, then twin independent or sidemount works fine. If you go to another site and they do have manifolded backmount then that works too. Each has their advantage and disadvantage, each has their weaknesses and strengths.

As I am not set up to dive side mount to date, I don't, however I do dive both manifolded and independent. Sometimes due to need I also dive a 15 litre backmount and a sling because of the circumstance. That works too for me.

Non of these rigs with the exception of backmounted manifolded, requires a lot of gear to set them up. In fact if you buy something like one of the Hollis wings, you can do twin backmount, twin independent, sidemount, single and sling.

My suggestion is to buy wisely at the start (unlike me). I have a BCD, cheap wing and now considering a Hollis wing which will allow all of the above options.

My suggestion is not to lever one style of rig to suit all situations, rather adapt to the circumstances and individual situations. Only in this way do you get the best result.

 

[Nemrod]

And then along came side mount.

For solo diving, when I carry doubles, I prefer independent.

N

 

[PfcAJ]

I think too many people get stuck on trying to prove one method is better than the other or the one you must use.

For me I adapt to the need and the situation. If you go to a site and they have no manifolded doubles, then twin independent or sidemount works fine. If you go to another site and they do have manifolded backmount then that works too. Each has their advantage and disadvantage, each has their weaknesses and strengths.

As I am not set up to dive side mount to date, I don't, however I do dive both manifolded and independent. Sometimes due to need I also dive a 15 litre backmount and a sling because of the circumstance. That works too for me.

Non of these rigs with the exception of backmounted manifolded, requires a lot of gear to set them up. In fact if you buy something like one of the Hollis wings, you can do twin backmount, twin independent, sidemount, single and sling.

My suggestion is to buy wisely at the start (unlike me). I have a BCD, cheap wing and now considering a Hollis wing which will allow all of the above options.

My suggestion is not to lever one style of rig to suit all situations, rather adapt to the circumstances and individual situations. Only in this way do you get the best result.

A jack of all trades is a master of none.

 

[Cap335]

A jack of all trades is a master of none.

Yes but you should always use the right tool and the more tools you have the better prepared you are.

 

[Remy B.]

Since so many people are diving sidemount these days which is just another form of indepenent doubles I don't see the big deal whether they are on you back or at your side. The gas management is pretty much the same.

I was thinking on back doubles and side mount stages for a total of 4 bottles

---------- Post added April 18th, 2015 at 01:03 AM ----------

My suggestion is to buy wisely at the start

That is the idea, I don't have a money tree, if I buy, it will be a one time good, and SB community have help me a lot in that, thanks