Why elbows instead of sweeps in plumbing?

Hvacman

Odd, it's in the line that feeds my kitchen sink... I suppose stranger things have happened. :-)

Tekkie

Curious

Were they too hard to manufacture/ too expensive so they didn't become practice?

bob young

sweeps

SWEEPS are code in nyc & essential for proper drainage. elbows are CHEAPER & when it comes to making money some plumbers are notoriously thrifty. elbows [quarter bends ] are for venting circuits or horizontal to vertical connections. short turn elbows used wrongly cause stoppages and sometimes it is almost impossible to get a cable snake thru them to clear the obstruction. no-hub clamps sure made life easier for a repair plumber.

mtfallsmikey

They

Don't fit too well in a joist span when used with a closet flange. I've seen vent ells used in that situation before, and inspected!

[Deleted User]

Are we talking water or drain waste and vent??

DWV requires the use of long radius fittings below the flood level of the appliance served.

On potable water fittings, the driving forces (70 PSI water pressure) overcome the pressure drop difference between short versus long radi fittings.

ME

Plumdog_2

Closet Bend

Sweep not required for closet bend(the ell beneath the closet flange).

mtfallsmikey

Well...

We did have an inspector many years ago try to enforce the use of sweeps under a flange!

Hvacman

Interesting thread...

My home (originally owned by a plumber)has some of the original piping intact, 1/2" copper sweep els both store bought and bent in the field... nice craftmanship that lasts.

edit: went down the basement, shut off the sillcock (forgot till now, and it's been cold!) and took some picts. In the first one this is an odd coupling? Why is the hex cast in or is it a check valve or other "special" fitting?

Charlie from wmass

Thats not a coupling that is part of your outside faucet. Make sure you removed the hose from it.

bob young

looks like it might be a cast brass reducing cplg.

mtfallsmikey

Just now

Looked at the pics....refrigeration fittings. We tried to use those long sweep copper ells on both line sets and the BB retro jobs.

Mark Eatherton

Note the fuzz at the face of the fittings....

That's a prime example of what happens if the joint is moved while it is in the process of setting up hard. It creates micro fractures that allow water to seep through the joint. Not enough to create an actual "LEAK" replete with drips, just enough to cause the white fur to grow over time (evaporation and salt deposition) until it eventually (hopefully) seals itself shut.

One should NEVER move a soldered joint until it is COMPLETELY set.

ME

Unknown

I'll have to

diagree with you Mark , although it pains we to do it You are one of the smartest guys I know .

I do exactly that a few times every job - maneuver a hot pipe with the solder in liquid state to get it straight . The torch is on the fitting as I do it though , which might make a difference . These newer solders are amazing too . They flow like 50/50 but they never come apart like 50/50 .

Mark Eatherton

Ron, you or anyone else is welcome to disagree with me...

People learn from open discussion. THe information I delivered was given to me by a retired gent by the name of John Barnes who was on a team that developed soldering for the Copper Development Association back in the 40's .

Soldered joints have numerous stages and phases. Warming up as well as cooling down.

On the way up, the flux starts out as a paste. As you apply heat, it becomes liquidus. Shortly thereafter it starts bubbling. Soon after that it goes dry. THAT is when you want to start backing off the heat. The joint is ready for solder. If you continue applying heat at that point, the joint will start outgassing and the copper surfaces will oxidize, and will not allow the "whetting" by the solder to occur. This is where the joint looks like a bird crapped all over it. Add at this point, there is no "fix" or "doctoring" that will make it hold. You've got to start over from scratch.

On a properly built joint, once you've gotten it to the proper flow point, the solder should flow freely around the joint, including upward through the power of capillary attraction, an interesting process in and of itself. The solder starts in solid form. When applied to the hot pipe surface, it becomes molten. Once inside the heated joint, it becomes liquidus and flows to fill the .002" gap between the pipe and fitting. This assumes an EVEN pipe surface temperature all around. If the joint is too hot or not hot enough, the solder will not flow evenly around the joint. This is what causes "holidays" in the joint. That and foreign dirt... from either the flux or the joint preparer.

The solder then begins to "set" when heat is no longer applied. It goes from liquidus to solidus in phases depending upon a lot of heat application factors. If the joint is disturbed while in transition, close to be coming solidus, it crystalizes, causing millions of micro fractures. This is what causes the joint to leak at such a low rate that it evaporates at the same rate it is leaking leaving the salts behind This issue can be overcome by reheating the joint to liquidus, and allowing it to set with no movement, like you do. Any attempt to reheat after the joint has seen substantial water will not work due to contamination. In your case, I'd even recommend putting a dab of solder on the hot joint right before it sets, to reinforce the joint.

Interestingly enough, the CDA recommends against wiping a molten joint, as most tradesmen do with the finger of their glover to make the joint attractive. This causes "wicking" of liquid solder out of the joint which inherently weakens the ability of the joint to resist tensile strength pull out. The recommendation is to knock any drips off the joint with the wire solder, allow it to set, then wipe it with a damp cloth to remove residual flux to keep the joint appearing nice over the long run.

I agree with you on the newer solders. It seems like the 96/4's do flow like 50/50. A heck of a lot better than the 95/5's out there...

Thanks for the kudos, and thanks for questioning me, and as Paul Harvey says', "Now you know the RESSSST of the storey..."

ME