New hose installation, how tight, where to get a torque wrench?

scubamikey · Jun 17, 2006

I'm installing my new SPG+hose (HP) and BC hose (LP) to the first stage, I'd buy a torque wrench if I could find a reasonably priced spanner style I could use on the hose ( I need 40-45 inch-pounds). Or do most of you just "snug it up" to finger tight plus 1/8 turn?

I've rebuilt car engines and other machines so I'm not worried about doing it correctly. I'm just wondering if anyone has a good source for the right tool, if you feel it is needed.

Also, do I lube the o-ring with silicone grease? I know some o-rings are meant to be used dry.

The Kraken · Jun 17, 2006

Mikey,

You don't need grease.
Just "snug" it down. It's a small, compressible o-ring.
Having messed around with engines you probably know what "snug" means with respect to an o-ring that size.

the K

redacted · Jun 17, 2006

Finger tight and then a little more. 1/8 turn + or - depending on the age of the o-ring (new o-ring will take a bit more). Just tight enough that it can not come loose is what you are after. I lube my hose o-rings but it will work OK without.

scubamikey · Jun 17, 2006

Thank you both.

Nemrod · Jun 18, 2006

The 45 inch lbs is not very much, it is finger tight plus about a 1/4 turn. The brass is soft--be carefull. I can turn close to that with my fingers. I know because among other things I am a mechanic and have a SnapOn box full of high dollars stuff, probably alltotal about 20,000 dollars of tools. You do not need a torque wrech, but if you did use a small 1/4 drive wrench you would use what is called a crowsfoot adapter also in 1/4 drive--from SnapOn. So how do you set the torque since the crowsfoot does not have the same center of force? Simple, believe it or not, when the adapter is turned 90 degrees to the handle the indicated(set) force on the wrench and actual force applied are the SAME. I work on turbine engine aircraft that cost millions of dollars, I know what I am talking about. N

idive2 · Jun 18, 2006

I've replaced a few hoses and o-rings, one side of me wants
to go more snug and another side realizes its just
brass or some other soft alloy. It would be interesting to see
how far after the average "finger tight" would be required to
get to 40-45 inch pounds. Interesting point on the position of the
torque wrench when using a crows foot to obtain true torque.

redacted · Jun 18, 2006

idive2:
I've replaced a few hoses and o-rings, one side of me wants
to go more snug and another side realizes its just
brass or some other soft alloy. It would be interesting to see
how far after the average "finger tight" would be required to
get to 40-45 inch pounds. Interesting point on the position of the
torque wrench when using a crows foot to obtain true torque.

Scubapro spec is 80 inch-pounds. I put the torque wrench on both HP & LP connections to the 1st stage to see how much more beyond finger tight with lubed o-rings. Used o-rings took about 1/8 turn while new o-rings took over 1/4 turn. Bottom line is finger tight and a little more so it does not come loose. Rather than over tighten, check the hoses often to make sure they are not coming loose.

Calvinandhobbs · Jun 18, 2006

For the torque wrench, try

www.mcmaster.com

scubamikey · Jun 18, 2006

I seem to have installed both hoses successfully with no leaks on a tank with 1900 psi left. This is a new Zeagle Flathead IV, the manual it came with said 40-45 inch-lbs. Actually there was little guesswork. New hoses and o-rings, no lube, the hose made a definitive stop at the end of finger-tight. Then I put the wrench on and it went about 1/16 turn and came to a point where it was obvious that I would need to really start cranking to get it to go farther. So I stopped. I suggest to anyone that you don't use more than your thumb and 1 finger on the wrench.

The HP hose protector was not going to go on, maybe someday I'll pay the shop to do that.

idive2 · Jun 18, 2006

Taking a break from outside, very warm in florida today. As I recall when
last replacing an o-ring on a hose I felt the hose was getting fairly snug
just about 1/8 turn past finger and thumb tight.
A smaller wrench makes it easier to feel the fitting as it gets snug. Anyone
that is not comfortable with any of these terms used in tightening hoses should
have this done by a qualified dive shop.

New hose installation, how tight, where to get a torque wrench?

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