On my cooling system I have reinforced silicone compound hoses (blue stuff from McMaster-Carr).  My system is set up with dual caps in series with the potential of 38 psi max pressure.  I put the hoses on, tightened them to what seemed right, then pressurized to system to 38 psi.  A couple of the connections leaked, so I got my ¼” drive ratchet with the appropriate socket, and tightened the clamp until the leak stopped.  I’m guessing it was about 30 – 35 inch lbs.  I checked them a few weeks later and found I could give most of them another partial turn to about the same torque level.  Haven’t touched them in the year of flying since, and there have been no leaks, and the hoses still look as good as when they went on.  I’ll probably replace most of them within the next year - just because.

 

Al

Al and all,

One of the best suggestions I've seen came from Carrol Smith's Prepare to Win book. He suggested that you should only use the stainless clamps with the full through holes for the worm. (hard to get anything else these days) The tightness is about right on a rubber hose when the hose bits poking through the worm drive slots are flush or above the level of the clamp material. Of courst you must check for leaks etc.. and YMMV, and all the usual disclaimers. The worm offers enough mechanical advantage that the actual torque reqirement would vary so much with various materials as to be hard to predict. A silicone covered hose might be slipperyer or stickier than a rubber one. When it stops leaking it is tight enough!

Bill Jepson