DA Pool Test Dive #1 Results

[pclarke1]

Hi team,

I just wanted to bounce some experience off against the community. I have been working through my DA rebuild (Circa 1967). I have rebuilt the 1st stage, replaced the 2nd stage with a HPR, new diaphragm, duckbill, wagon wheel rubbers and band clamp. In transit to me are new hoses, mouthpiece, banjo and hardware.

I don't have vintage backpack as yet, so I reused a backpack from an old BC (I am aware of the implications to breathing effort of this). A VDH backpack will be part of my next order from Brian (they were out of stock earlier this month). The backpack seemed to hold the regulator 4-5 inches off my back, and it seemed to site behind the base of my neck. For this test I was using the original hoses and mouth piece (both in great condition) in the pool where I live in Singapore (about 5ft of water), no BCD for this test. Tank was steel and started at 3200 psi (220 bar). The IP started at around 130-135 psi, I didn't check the ending IP or tank pressure. I spent about 20 minutes playing around, then passed it over to my 12 year old son (pictured) and he ran it for another 30 minutes or so.

My observations here seem to tally with what I have read. When swimming face down breathing efforts were quite high, not too hard, just uncomfortable. Upright it breathed very well, head down quite bad and on my back it fell like it was trying to fill me like a balloon animal. All of these I was expecting from the type of backpack used and other things I read on the forum. Question, when I get my VDH backpack is the breathing effort likely to be similar face down as upright?

My other observation was that when I was upright my exhaust effort seemed higher (duckbill) than with a regular single hose. Can I expect this to be better with a DBE? Also it seemed to take quite a lot of effort to blow out water if it filled the exhaust hose and took several breaths to clear it fully. Is this usual?

A further question relates to post dive. I noticed in my air supply hose when I was cleaning up my gear, that I had quite a lot of water in there. Is this normal, will it be different with my new silicon hoses and mouthpieces. Could this be a sign that I have incorrectly assembled by wagon wheels. I disassembled and dried the first stage with compressed air before packing it away.

I will probably not pool test again until I get my new back-plate, unless I learn something new here that makes another test worthwhile at this point.

[Herman]

If the reg was 4 or 5 inches off your back, then that is going to add quite a bit of cracking pressure to the reg. Do you know what the cracking pressure is above water? The reason I ask is we are assuming you are starting with a correctly set up regulator and without being there I have no way of knowing. With a HPR and new diaphragm, it should be between 3/4 and 1 IWC.
The proper backplate will not eliminate the differences between face down and face up position but it will change the differential. By that I mean there will still be a difference but the amount of the difference will be less noticable. I don't notice much difference with my regs but I have been diving them for a long time so it may be that I am ignoring it.

In my experience, the DBE is not that much different in feel as compaired to the silicone duckbill. When you are exhausting a lot of water from the hoses, it is not unusual for there to be a fair amount of pressure required to remove the water, remember you are moving a fair amount of water and water is heavy. Each of us has different techniques to clear the hoses. For a hose with a lot of water in them, I roll onto my left side for a few seconds to allow the water to drain down then do a long slow exhale to clear out the major portion of the water, then take a large breath, start exhaling and continue the roll through a full 360 rotation continuing the exhale for at least 200 deg of rotation. For a slight but anoying amount of water in the MP, I roll on my side, pause then rotate to almost 180 degs followed by a fairly quick exhale.
Its not overly unusual to have water in the supply hoses, esp if you were playing around and flooding the hoses and MP on purpose. As you breath the MP valves open and if you are turned to the side, water will seep in. When you go head up or roll on your back, that water will run into the cans. It is possible to have a small leak in the body gasket or a small cut in the hoses that will allow water to enter the reg and you should check for those but odds are the water was simply seeping around the MP valves when you are in positions other than head down. If you start a dive with a dry set of hoses, do not take the MP out of your mouth, don't flood it at the surface before a dive or do a lot of non face down positions my bet is you will not have any water in the supply hoses at the end of the dive. The exhaust ones will from the moisture in your breath and saliva...which is the reason the hoses need to be rinsed well and throughly dried after a day of diving. Silicone hoses and MPs will not have any effect on clearing water from the reg or water accumilating in the supply hose..

[pclarke1]

Herman,

Thanks once again for your response. I do not have any way of measuring my cracking pressure. It feels a little more than my single hose out of water but not by much. When upright it is very low, I would be worried if I reduced the effort much more than I would get free flow pressure when upright. Bottom line is that it seems to be working and to get a better read on the breathing effort I will need to get the right backpack. I will report more on this when I have the new backplate (a couple of weeks from now).

With reference to exhausting the water from the reg. I was upright and level when trying to do this. I will work on my technique, I didn't pick that up in my research.

As for the water in the air supply hose. I thought I may have noticed some bubbles coming from the air supply horn/hose interface when my son was diving the reg. However I can't be sure (they were pretty big bubbles and more likely came from the exhaust) and was not bothered by this as my new hoses are on their way. I didn't notice any water getting in while I was actually using it. I also recall that prior to pulling the unit from the pool I switched off the air and the hoses probably went under water at that point.

Sorry for all of my questions, but I am attempting to establish what is and is not normal for these things without the benefit of a local mentor.

[usddude]

I have two DA's. One has a Phoenix and the other has a Royal nozzle in it. So both of mine are balanced and breathe great. I have never used a standard DA but should work fine if properly tuned even though unbalanced. I suggest a Phoenix for your DA. You will like it. You know technique and position of regulator is important as well. VDH sells balanced nozzles for DA's and not expensive, especially considering the improved performance its a deal. The regulator touching my back between shoulder blades improves performance. You probably know that. I have not been on the forum in a while, so I know nothing about you. For best exhaust make sure duckbill is centered correctly, info is here on forum. Luis had an in depth instruction with photos on that.

Steve

[pclarke1]

At present my plan for this particular DA is a more or less vintage rebuild, with a number of exceptions, HPR and silicon everything. I have also ordered yellow hoses (just because I like them) which are not age appropriate for a 1967 DA. (So really less vintage rather than more).

For my 2nd DA (yes I now have 2, the 2nd being a short yolk West Warner 65 or 66), this one will get the fully Happy Meal, new chrome, Phoenix, HPR and once again silicon everything. That wont get started until I get #1 tuned and have dived it in the open water a couple of time (translate, until I know more about what I am doing).

To help out with the set up of #1, I have ordered a Magnehelic gauge ($10 on Ebay), to make sure that I get the reg setup correctly. I will report on my results.

[BigMike]

For my 2nd DA (yes I now have 2, the 2nd being a short yolk West Warner 65 or 66), this one will get the fully Happy Meal, new chrome, Phoenix, HPR and once again silicon everything.

Welcome to the addiction.. I love the "happy meal" reference