If those hose clamps are not constant
torque clamps, please consider upgrading them before first flight.
They're available from McMaster.
Mark;
I have no objection
to the use constant torque clamps, of course. But I will express my
conclusion/opinion that this clamp thing has been over sold. Certainly
not picking on you, and I know our friend on the other list makes a big issue
of the constant torque clamp. IIRC, the main point raised was the effect
of thermal expansion, more exactly the differential thermal expansion between
the inner metal tube (aluminum in this case) and the clamp (usually SS).
Doing the math will show that this is less than infinitesimal. The
temp change of the coolant may be about 80 C cold to hot. The clamp
heats up maybe 15C less than the aluminum. Assume a 1 ½ diameter. So
the aluminum expands about 0.000037 on the diameter while the SS expands only
0.000012; a huge difference of 0.000025. I am certain that this effect
on the thickness of the elastomer hose is entirely negligible. And besides,
having that clamp just a wee smidgeon tighter when it is hot and pressurized
cant be a bad thing.
Now, it is true
that over time the elastomer loses some of its elasticity, mostly over the
first few months, and then very slowly over the next few years depending on
the type of elastomer, of course.
So whether they are
regular good quality clamps, properly tightened (not over-tightened), or
constant torque clamps properly tightened; Id suggest that the important
factors are: re-torque the clamps after a few weeks or a month of use; use the
widest clamp for the diameter, and consider high quality silicone hose
although contemporary automotive coolant hose can be expected to last 6 9
years. The other thing, of course, is that on our planes we will
probably change out the hoses every second annual or so
anyway.
One more
thing. Consider putting a Schroeder valve on the system somewhere so you
can easily pressure test the system before you fly (or before you start your
engine), and maybe at annual time. It is so much easier to deal with any
leak while things are cool and on the ground.
Sorry; did I go on
too longJ?
Al
G