CCR hose and fittings configuration

[craig haymaker]

Hi all, after reading through the Swagelock QC6 thread and leaving a question at it's end, I thought that maybe I should start a new thread on hose config. Very quickly, I am at the TEC 60 CCR Poseidon level. I have rearranged my hoses configuration several times (because I love monkeying with this stuff) ! I have been using the DGX style locking ring QD on everything, including my offboard regulators. BUT I have "always" had the female side QD on the supple pressure side, and it's male counterpart on the receiving downstream side ! I have these QDs on my BOV, both MAVs, the E-module's Dil & O2 inlet ports and on my offboard regulators. I tried the QC6 (check valve version, not shut off) on my lean and rich offboard whips, but found them harder to connect and disconnect under pressure while UW ! So I went back to my trusty DGX QDs. My thought was that those offboard whips could go a number of places if needed (but not to the E-module). So - when I read that the QC6 male w /shutoff should go on the supply side, well I guess it's time to do some learning again, lol !
Where should I use these QC6 QDs, and should I retain my DGX QDs elsewhere ? One last question if I may please : After diving in St. Criox in November, I seen what looked like rust appearing inside the female side QD on the QC6s, what's that about ??

 

[craig haymaker]

In a short continuation of above; in a dive team situation (although I prefer solo), would I normally expect to see their bailouts equipped with this QC6 MALE w/ shut off on their whip ? Thanks all.

 

[grantctobin]

The standardization in cave diving has narrowed to male QC6 on offboard bottles and female QC6 on the rebreather side. They are DESO (double ended shut off) and as such, do not require in line shutoffs. The advantage of the male on the supply tank is that it’s easy to dislodge debris by pressing into the nipple and this cleaning the supply side outlet from any dirt/sand/etc.

I use them for all diluent connections and keep a Female QC6 to female BC nipple “cheater” in a pocket. My O2 MAV has the ability to accept an offboard BC inflator hose.

I’m not very fond of the DGX nor the Omni-Swivel connectors and haven’t found a use for them where something else wouldn’t do the trick. You could keep one on your BOV (if you have one) to be able to quickly disconnect for cleaning.

 

[tbone1004]

My general rule is the CEJN style fittings, omniswivel/DGX/etc, are best used on things that are not intended to be disconnected during the dive but are something that is disconnected for storage/cleaning. BOV, head connections, etc.
QC6 is the standard for offboard bottles, but if you aren't doing dives where you are connecting them regularly or sharing bottles with teams, then I wouldn't worry about it terribly. I do most of my dives in cave country so all of my bottles really need to keep them as standard, but if I was open water diving I would be much less inclined to go through the expense of using them when the DGX ones work well enough.

Of note, the DGX style ones let a couple of drops of water in when connecting underwater where the QC6's only let a fraction of a drop of water in, so keep that in mind if you're in the salty stuff and you plan on plugging/unplugging these things.

 

[craig haymaker]

Thanks tbone, I have always respected your knowledge, I've got a couple more QC6s coming, and will do it right !

 

[JahJahwarrior]

What's the flow rate of those DGX quick disconnects at depth vs. a QC6?

 

[wedivebc]

Of note, the DGX style ones let a couple of drops of water in when connecting underwater where the QC6's only let a fraction of a drop of water in, so keep that in mind if you're in the salty stuff and you plan on plugging/unplugging these things.

I did an experiment one time with a QC4 and QC6 to see how much water they allowed in. I connected each while submerged in a bucket then purged the line into a clean paper towel. The QC4 resulted in a wet spot about the size of a dime, the QC6 resulted in a spot the size of a loonie (about one and a half inchs for all you Americans out there). That seemed like a lot of water to be putting through my rebreather, especially the oxygen feed to the solenoid. Meg was having a rash of solenoid failures at one time resulting from instructors who though it was an important skill to disconnect and reconnect your O2 feed under water. ISC highly discouraged this practice.

 

[PfcAJ]

I did an experiment one time with a QC4 and QC6 to see how much water they allowed in. I connected each while submerged in a bucket then purged the line into a clean paper towel. The QC4 resulted in a wet spot about the size of a dime, the QC6 resulted in a spot the size of a loonie (about one and a half inchs for all you Americans out there). That seemed like a lot of water to be putting through my rebreather, especially the oxygen feed to the solenoid. Meg was having a rash of solenoid failures at one time resulting from instructors who though it was an important skill to disconnect and reconnect your O2 feed under water. ISC highly discouraged this practice.

If I recall correctly, the spec for QC6 is 1cc of water in, each time you connect.

I made an adapter that goes from a garden hose to a male qc6 so I can rinse out the 'breather side of the equation after a saltwater dive.

 

[craig haymaker]

I did an experiment one time with a QC4 and QC6 to see how much water they allowed in. I connected each while submerged in a bucket then purged the line into a clean paper towel. The QC4 resulted in a wet spot about the size of a dime, the QC6 resulted in a spot the size of a loonie (about one and a half inchs for all you Americans out there). That seemed like a lot of water to be putting through my rebreather, especially the oxygen feed to the solenoid. Meg was having a rash of solenoid failures at one time resulting from instructors who though it was an important skill to disconnect and reconnect your O2 feed under water. ISC highly discouraged this practice.

You are correct in that the QC4 emits less water than the QC6 when being connected UW ! And as I recall reading in Swageloc specs, it is stated there ! I guess that is the price we pay to go for the higher flow rated QD !

 

[wedivebc]

If I recall correctly, the spec for QC6 is 1cc of water in, each time you connect.

I made an adapter that goes from a garden hose to a male qc6 so I can rinse out the 'breather side of the equation after a saltwater dive.

thanks, that pretty much tracks with the results of my experiment then.