Mark 15, 15.5, 16 Spheres...anyone?????

koputai

You can use Apeks US4 or DS4's hard mounted.

Cheers,
Jason.

chunter

What IP do you run them at?

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DZLHED

Dave,

You mentioned, "I recognize those Draeger firefighting valves in Phi's old Inconels... old Kleinkonish valves sent to me by Matthias, rethreaded on my old lathe, and then sent back to Matthias..... ;-). I still have 50 of them if anyone else needs DIN valves for Mark-15 spheres.

Care to part with four? I have two sets of spheres and I'm tired of my o-rings falling out.

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Dieselhead

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Dave Sutton

I might as well get down to re-threading another dozen. I'd prefer guys to send me spheres so I can fit each set... but probably not viable from Hawaii. Bottom line is that "Yes" I can set you up with the DIN valves, if I don't have a sphere here of yours to work to, I guess I just need to dump one of mine. I bought the threading die long ago, it's just a matter of getting the O-Ring groove just right (again). Fortunately there is enough extra material on the old Draeger valves to allow reduction of diameter on the lathe and then re-threading.


Dave

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teksimple

I will second Charlie's question. Note that the oxygen and diluent regulators were designed to operate at significantly different pressures. ~170 psi for the O2 reg, ~240 psi for the diluent. If you have the often used stainless spring (which mine came with) on the diluent side, the ~170 psi that is delivered is just not enough to fill the counterlung very quickly. If you are doing a rapid descent, bottoming out the counterlung happens very easily.

The longer mil-spec inconel spring cranks up the diluent pressure to something that can fill the counterlung in just a few seconds.

Not sure if those Apeks were designed for such high intermediate pressure. Anyone seen what the IP is when the adjustment screw is bottomed out?

Colin at Colkan has inconel springs for the Sherwood regs, but be aware that you will also need to replace your high pressure seat because the previously worn indentation on the seat at that higher pressure causes a leak.

decoweenie

Apeks spring comes to a solid around 12.5bar/180psi. I used to set my KISS valve as close to that as possible (i.e. 12 bar).

As fas as Apeks on MK-15, I only kept my Apeks IP at 10bar and didn't notice any delay personally.

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Dave Sutton

In theory... yes. In practice... no. The IP is not that critical, and the original Mark-15/CCR-1000 used 140 PSIG IP, not the higher Mark-16 IP of 240. Many of us are running BOV's and suit inflate, etc., from internal diluent and adjusting the diluent IP to one that suits those needs is a pretty common desire. I've found that the Apeks and Poseidons (300, not the 5000) fit well and work fine. 140 PSI seems to be just fine for the ADV Schreader, as long as you "dwell" against the ADV on a fast descent, meaning that you inhale to bottom the lung and just pause the inhale. This is more an issue at the first 10 meters than anywhere else. Once thru 20 meters it's not an issue anyhow.

Dave

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heyydude

The "technique" (if you can call it that) that all the guys who dived with me (and were on 15's) was to "ride" the Diluent Manual Add during a fast descent.

In my mind - having to essentially "suck" against the Schrader valve is asking for trouble.

That is why the USN increased the IP of the Mark 16 to around 275 psi. They also went down to 1/8th tubing everywhere (the Mark 15 has lots of 3/16" diameter stuff).

You don't necessarily need to change out to the different springs - I've also added Shims to many Mark 15 1st stages to increase the I.P.


The Mark 15 and 16 share the same Schrader Valve, and the Mark 15 Manual Add Valve can handle high pressure, so there is nothing to damage there.

However - this does prevent you from using your on-board bottle for an Open Circuit 2nd stage reg (a practice that I do not agree with anyway).

Don't put yourself in a position where you need to "wait" for you rig to make up gas. It's uncomfortable at best, and dangerous at worst.

Kevin Juergensen
Juergensen Marine, Inc.

Dave Sutton

Dude,

We usually feed our drysuits from air in the sphere and run offboard gas (trimix) to feed the rigs diluent needs anyhow. Unless you are also putting a 240 PSI offboard diluent cylinder regulator on each stage bottle you're going to be running 140 PSI gas into the rig anyhow anytime you use offboard gas.

As far as "where you carry air and where you carry mix". (IE inboard or offboard), we have found this: The advantage of using air in the sphere with suit feed, etc., is that the rig makes a good "naked" Nitrox rig at that point and then the diver can simply hang on any old trimix bottle as offboard and the rig becomes "plug and play" as far as depth is concerned. Grab whatever mix bottle is right for the day and snap it on. The sphere always has air in it, feeding the drysuit and available as inboard gas if needed (IE SCC Bailout deco)

Bottom line is that the onboard regulator other than drysuit feed does jack-shit most of the time anyway as far as feeding the rig and it's IP is really irrelevent. And nobody is using 240 PSI first stages on their stage bottles either. I guess you could use trimix in your sphere, but you'e then fooling with filling up the spheres more often, which is a pain in the ass on a multi-day trip. I'd rather just bring a stash of offboard bottles and basically just keep the sphere topped up every now and then with air.

Dave

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