Low pressure BCD hose assembly question.

[bigduke12]

Just bought a new set of Mares regs. They came set up, but without a low pressure bcd inflator hose. I believe I can take the one from my old set up as it's relatively new. Lightly silicone grease the o ring and thread. My main question is how tight should it be? The consensus seems maybe a half or quarter turn past finger tight? I also believe the hose is standardised throughout the industry?

Thanks in advance.

 

[herman]

I really do not like the idea of some specific distance, what is important is how much torque you put on the connection. What I suggest is tighten it finger tight then using 2 fingers pull the connection up snug. Unless you have gorilla hands, using just 2 fingers keeps you from over torqueing the connection. Bottom line is, the oring does the sealing and as long as the connection will not come loose it's tight enough. The amount of torque on an oring connection has nothing at all to do with the connection sealing and if a connection is leaking, more torque is never the answer to fix it.

 

[WhiteSands]

Just bought a new set of Mares regs. They came set up, but without a low pressure bcd inflator hose. I believe I can take the one from my old set up as it's relatively new. Lightly silicone grease the o ring and thread. My main question is how tight should it be? The consensus seems maybe a half or quarter turn past finger tight? I also believe the hose is standardised throughout the industry?

Thanks in advance.

You can lightly grease the o-ring, but don't grease the threads.

Finger tight, then till lightly snug with a wrench and no more. Half a turn sounds way too much.
I'd guess 1/8 turn or even less will do it.
It will hold gas even when finger tight, so err on the side of too loose rather than too tight.

The inflator hose normally comes with your BCD or wing. So that it works with your BCD or wing.

 

[bigduke12]

Thanks for the replies!

 

[tbone1004]

the importance of torqueing is the following.

there is what is called "backlash" in any threaded application, this allows you to actually screw the threads in with relative ease. When you are creating a sealing surface with an O-ring, you need to compress the o-ring slightly so it pulls the threads back to take up the slack in that backlash and the torque you are creating is the friction of the threads against each other. If you lube the threads, you decrease the friction and will overtorque the connection, super bad for the o-rings lifespan.

There are official torque specs on most hose connections, but to do it properly you have to have a crows foot to attach to a torque wrench and most people don't have that. Since crows feet are relatively rare, the industry accepted "rule of thumb" is "snug", or until the flange hits the body. You'll see what "snug" means the first time you put it in.

 

[kwinter]

Like others have said, "finger tight, plus a little". Not even 1/8 of a turn. It only needs to be tight enough that you can't unscrew it by hand.

 

[knotical]

For the minority of us who sometimes use torque wrenches: http://www.scubaboard.com/forums/regulators/156611-how-tight.html#post2182648
i.e. 30 - 40 inch-pounds.

 

[bigduke12]

Thanks for all the replies. Gave the o ring a light silicon greasing, tightened as much as I could by hand, and finally a little kiss with a spanner. By the time I had hand tightened, there was basically not much room for further tightening.

 

[Nemrod]

I use a torque wrench on my bench. If I am on a boat or away diving of course I just run it in finger tight and then just a little from a wrench. I keep my second stages finger tight at the body. I do not generally put grease on the static O-rings of hose connections as it is an opportunity for the O-ring to extrude.

N

 

[dumpsterDiver]

I don't recall ever snapping off a hose fitting by over tightening, but I probably have done it once or twice.

I have always worried about corrosion and I liberally grease the metal threads of the hose and the O-ring. If I am messing with a regulator, I will often remove the port plugs and grease those before re-inserting them as well. I tend to always apply a thin coat of silicon grease to any metal to metal fitting on stuff that goes in saltwater.

My gear gets more use than most recreational divers and my maintenance cycles are probably longer than recommended, but I never seem to have a problem with corrosion at the connections or O-rings popping out.