I've gotten several off-net emails wondering why I'm considering AN style
flare fittings for my oil lines. A very valid question with broad enough
interest that I thought I'd address it here. Mainly, it's a better system
that the SAE 45deg double flare. It was developed by the military(thus the
designation AN for Army/Navy - it's also sometimes referred to as JIC)
between the two world wars to be a reuseable, field serviceable connection
for aircraft plumbing. The SAE double flare is a production system designed
to be used once. The SAE system seals by crushing the joint and deforming
the components. The AN system seals by stretching the concave section of
the flare over the convex section making a resealable connection with less
torque required. The only advantage that SAE has over AN is that it's
cheap.
While it relates mainly to brake systems, the following page is a pretty
good discussion of the various sealing systems:
http://web.dimebank.com/tech/BrakePlumbing.html
I would also note that it's not required to use SS braid armored hose with
AN fittings. Both Aeroquip and Russell offer a polymer covered hose for use
with their fittings. A word of warning, most manufacturers recommend you
use their hose with their fittings and often they produce specific fittings
for different models of hose. IMO, I would follow this advice strictly.
These things were developed and tested as a system(including assembly
methods) and I'd hate to find out the hard way that my Russell hose fittings
wouldn't stay attached to my Aeroquip hose.
My .02, fwiw...
Patrick
flare fittings for my oil lines. A very valid question with broad enough
interest that I thought I'd address it here. Mainly, it's a better system
that the SAE 45deg double flare. It was developed by the military(thus the
designation AN for Army/Navy - it's also sometimes referred to as JIC)
between the two world wars to be a reuseable, field serviceable connection
for aircraft plumbing. The SAE double flare is a production system designed
to be used once. The SAE system seals by crushing the joint and deforming
the components. The AN system seals by stretching the concave section of
the flare over the convex section making a resealable connection with less
torque required. The only advantage that SAE has over AN is that it's
cheap.
While it relates mainly to brake systems, the following page is a pretty
good discussion of the various sealing systems:
http://web.dimebank.com/tech/BrakePlumbing.html
I would also note that it's not required to use SS braid armored hose with
AN fittings. Both Aeroquip and Russell offer a polymer covered hose for use
with their fittings. A word of warning, most manufacturers recommend you
use their hose with their fittings and often they produce specific fittings
for different models of hose. IMO, I would follow this advice strictly.
These things were developed and tested as a system(including assembly
methods) and I'd hate to find out the hard way that my Russell hose fittings
wouldn't stay attached to my Aeroquip hose.
My .02, fwiw...
Patrick
