when do you use long sweep elbows in a copper supply line?

or are these for special applications?

when you screw up and cut something too short, they save the day.

or when you wish to reduce turbulence INSIDE the tubing - ie. best practice

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

When you are not in a tight spot and money is no object.

Bernabeu's thoughts about less turbulence are right on.

When I worked for L.A. County Mechanical Department in the early 1970's quality was most important and cost to the tax payer was never a consideration and so we mainly used long sweep copper 90's (as well as exclusively using type K copper pipe).

If the fluid's velocity is not excessive, turbulence is seldom a problem.

Right on hj. Note that the velocity in type K compared to L and M will be faster/increased due to having a narrow inside.

That said I'm not suggesting that long sweeps need to be used in most cases.

Is using long sweeps "better" than short sweeps? I'd say so however in virtually all cases not necessary.

oversized piping results in too low velocity and 'stagnation'

undersized piping results in too high velocity which 'erodes' piping and causes turbulence in changes of direction resulting in HIGH erosion

copper tube is 'rated / designed' for 2-6 ft per sec velocity with 3-1/2 being 'ideal'



sooooo, if you think that a 'branch' will 'barely' meet demand then use long radius fittings for any change in direction

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638