Can you identify this first stage?
- Thread starter sixof1or2
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One thing a lot of people don't realize is the reason for that LP outlet on the top of the first stage. It came about because Scubapro was embarrassed by the U.S. Navy Experimental Dive Unit tests which showed it's less expensive model (Mk II?) with only one LP outlet on the top out-performed the Mk V. This is because of basic fluid dynamics which show that when you bend a flow 90 degrees, you place a lot of turbulence into the flow. By having the flow go straight out of the piston into the hose without having to make a turn, the internal turbulence is lessened, and the regulator performance is enhanced. I had a commercial diver show me his rig, and he had a Scubapro first stage hooked up to a full-face mask. I told him that if he had a particularly strenuous dive, he should hook up that main LP hose to the top of the regulator. This is not well publicized even now. So looking at the top photo, the regulator will perform better, especially on deep dives, if the second stage is hooked to the top, rather than a side, port. It may be a bit inconvenient for hose routing, but it works very well.
SeaRat
SeaRat
Yes, you could put a yoke on your reg..... getting a 3000psi yoke would be no problem but maybe more difficult to find the right yoke nut.
-The 2nd try at the MK1 was the MK5 body with a single outlet LP end.-
(or the MK5 was a MK1 with a multi LP port swivel)
-The 2nd try at the MK1 was the MK5 body with a single outlet LP end.-
(or the MK5 was a MK1 with a multi LP port swivel)
R
redacted
Guest
That would be a real shame. What "issues" are you concerned with?
sixof1or2,
I doubt you can ever pull that regulator off the valve, like what was described, unless you run completely out of air. The incident described above probably would have resulted in a drowning whether the regulator stayed on or not, as I'm pretty sure that guy was completely out of air, and pulling a vacuum on the regulator. The fact that the regulator came off probably was incidental to the actual accident, but was used to get a huge settlement from the diving companies. Put this reg on a tank with ~200 psig, and see whether you can pull it off. I doubt it.
SeaRat
I doubt you can ever pull that regulator off the valve, like what was described, unless you run completely out of air. The incident described above probably would have resulted in a drowning whether the regulator stayed on or not, as I'm pretty sure that guy was completely out of air, and pulling a vacuum on the regulator. The fact that the regulator came off probably was incidental to the actual accident, but was used to get a huge settlement from the diving companies. Put this reg on a tank with ~200 psig, and see whether you can pull it off. I doubt it.
SeaRat
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John,
You are so correct--But the victim breathed the tank totally dry, some time during that process the regulator disconnected from the tank. I, like you, suspect it was at the very end under a very panic situation with a sustained demand on the air supply.
You are one to experiment--- Why don't you examine at what pressure a regulator can be disconnected from a tank and report back? I and I suspect others would like to know..
SDM
You are so correct--But the victim breathed the tank totally dry, some time during that process the regulator disconnected from the tank. I, like you, suspect it was at the very end under a very panic situation with a sustained demand on the air supply.
You are one to experiment--- Why don't you examine at what pressure a regulator can be disconnected from a tank and report back? I and I suspect others would like to know..
SDM
Good idea Sam.
I just went out to my laboratory (garage) to experiment.
If the pneumatic yoke is properly adjusted, it will pressurize and seat with less than 100 psi. However, even if properly adjusted a bump or a sideways tug on the first stage can cause unseating at 400 psi and a leak at 750 psi.
Couv
I just went out to my laboratory (garage) to experiment.
If the pneumatic yoke is properly adjusted, it will pressurize and seat with less than 100 psi. However, even if properly adjusted a bump or a sideways tug on the first stage can cause unseating at 400 psi and a leak at 750 psi.
Couv
From my experiences with pneumatic tank fillers I have to agree with COUV that it could become unseated at surprisingly high pressures.
Sam and all, I went to my LDS, Pacific Watersports, and talked to them about the pneumatic yolks. I had made a dive a few days ago, and had a mostly empty tank. We hooked my steel 72 to a pneumatic yolk they use for filling at 500 psig tank pressure, and noted that I could move it, but not unseat it. They also had a pneumatic gauge, and so we hooked that to the tank, pressurized the gauge, then turned the valve off so that only the small area around the valve was pressurized. I could not displace it at 500 psig, but could cause a slight leak by pulling and simultaneously twisting the gauge. When the gauge got to 50 psig, by twisting, pulling and pushing at 90 degrees to the gauge yolk's alignment, I was able to release enough to get the O-ring to displace and cause depressurization. I figure that using a 3x safety factor, it would be extremely difficult to happen above 150 psig. But it can happen with some pressure and enough force applied. Chances of this occurring during a normal dive are very low, and would include exiting on a boat and getting the SPG caught in a ladder, or something like that.
SeaRat
SeaRat
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