MK11 Octo or 2nd Stage on HFP ?

[Kyl3]

Just acquired MK11 C350 set, LDC set it up for me , on inspection when returning home noticed 2 things; Firstly the first stage was setup with the Diaphragm holes(black cap) facing upward when octo/2nd coming over my right shoulder. My first question was is this right ? After some reading on numerous forums the conclusion was that it doesn't functionally matter but would be preferable to have it face downwards to provide a little more headroom as the black cap extends about 10 mm further past the the center of the valve , we not talking a huge improvement but every bit helps . Not a comment on forums but I feel having the holes at the bottom allows water and sand to flow or fall out when in the nominal position. Anyway with this thinking was about to change the first stage around and then noticed that if I did and I wanted to keep the octo low and 2nd stage high , octo under the arm and hence coming out of the lower port , 2nd stage over the shoulder and coming out the higher positioned port , Diaphragm holes(black cap) now pointing down to my feet , sounded the best routing, would put the octo on the HFL port and the 2nd stage on just the normal LP port. So my second question, is this the design intent to have the octo which is harder to breath from normally assigned to the port that delivers 15 % more air or is it preferable to have your 2nd stage on this HFL port for easier breathing during normal dive or wont one be able to tell the difference. I read through the manual and cant find any reference to which port is actually the HFP port , I know its engraved and I don't know if I am overthinking it but the labeling on the first stage seems ambiguous, does the HFP reference the port opposite , the port which has no engraving and which is next to it and the LP below to the port in question as in the picture below, or is the engraving only for that port (HFP - LP) which also doesn't sound right, its like saying the very fast red car , red car . The other LP port doesn't have any labeling and one must just know that the LP ports are smaller. This thread is not Critique but just hoping someone from scuba pro can assist me with a picture and labels pointing at the ports which are HFP and which are normal LP ports to clear up my ambiguity and share the design intent around octo on HFP or 2nd stage on HFP ?

 

[Random Dude]

Not ScubaPro personnel, but I use the MK17s, which are just the sealed version of the MK11s, so thought I would share things that I found out via research when buying my regs.

For the first question, I'm of the mind that it does not really matter whether the diaphragm is right side up or right side down as long as you rinse your reg thoroughly after a dive.
Modern day first stages are unlikely to malfunction just because of a little bit of dirt or sand inside them. Also, if you have accumulated dirt that you can't rinse off, I don't think that gravity would do much help in letting it trickle out.
Your main concern here should be whether the setup allows you more freedom when you raise your head. If it gets in the way, then turn it around to get the extra headroom.
Nevertheless, if contaminants in the first stage really bugs you, perhaps you can ask your LDS about upgrading the MK11s to sealed versions (MK17s) to provide some peace of mind for you. Theoretically, the upgrade should also increase the cold water resistance of your regs.

As for the second question, my MK17s have the same design too, 4 low pressure (or intermediate pressure as SP calls it) ports with 2 designated as "high flow" ports.
Theoretically, high flow ports are designed to allow better flow of air, so are usually recommended to be used on your main second stage so that you can take max advantage of the higher flow of air.
However, gathering up what divers experience in real life usage, no one can really feel the difference between high flow or non-high flow ports, so I am of the mind that it might be more of a marketing gimmick than a real concern.
Therefore, I would recommend that you stick to whatever configuration you feel most comfortable with, and not let the ports bug you too much.

As for the last question, I'm pretty sure that the port closest to the HFP letters are the so called high flow ports, instead of the adjacent unmarked ones. The unmarked port is the "normal" low pressure port, and the one marked HP is the high pressure port.

Hope that helped!

 

[Kyl3]

Evening Melvin, Thanks for taking the time to reply to this thread. We don't dive in murky water so not really concerned about debris. It was more of a hypothetical situation with regards to dirt. Going to stick with the MK11 for now. I am going diving in about 2 weeks time so will see how it goes . Going to work on the assumption that the engraving is for the HFP and work from there. If I can play in a pool I will switch them around and see if I can tell the difference, probably wont though ;-)

Thanks again

 

[Random Dude]

You are more than welcome.
Those are good regulators, and so shouldn't bring you any big issues.
Dive safe!

 

[herman]

The "high flow" ports are another marketing gimmick. While in fact they can flow more gas that other LP ports.....with the port open with no hose on it and with a supply capable of flowing more gas than the reg itself (which a regular tank valve can't ) it makes no difference at all because the limiting factor in the chain is the second stage itself. Any port on any modern reg can flow several times more gas than the best second stage on the market so it makes no difference which port ( or reg) the second stage is hooked to. This is also the reason that making a big deal about a flow through piston reg being able to flow more than a diaphragm reg can, while true, is a moot point since any modern first stage can flow more than any 2 second stages on the market.......and to top all that off, any modern second stage can flow several times more gas than any diver can breath.