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1/4 inch per foot equals ???

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209K views 28 replies 19 participants last post by  DJLland  
#1 ·
Hi everyone.

I know my 3 inch horizontal drain has got to be at a 1/4" per foot

My question is..

What would 1/4" per foot be equal to in degrees ?

I've looked on the internet for this answer and I havent had much luck. Your help is appreciated.
 
#3 ·
I was going to start a thread about this...

I wanted to clarify the distinction between the "2%" usually referred to with longer runs and larger pipes vs the 1/4" P/LF usually referred to with shorter runs and smaller pipes.

eg: When I trench to re-route 70 linear feet of 4" main/waste pipe I'm told I can use 2% (70x12 x .02) or 16.8" because I will dearly need that 3/4" (vs 17.5").
 
#5 ·
One degree could be equal to any length depending on how far from the point of origin you are making a measurement. It is not normally a function of length.

One degree can be broken down into 60 minutes or 360 seconds.
 
#8 ·
And for this length of pipe it'll be helpful to know what I can set it at.
I don't know anything about this whiz-bang gizmo you have, but...

If Point "A" = X" (below some known grade level or such)...
then Point "B" 100 linear feet away MUST be 24" shallower than X.
(100 x 12" x .02)

For the 1/4" P/lf method... 100' x .25" per = 25" shallower.

If you don't have a transit...
try some clear vinyl hose with water in it.
after an annoying ad: http://www.youtube.com/watch?v=NhDbv9xMXJs

http://www.deckmagazine.com/article/64.html
 
#10 ·
#12 ·
#14 ·
Idk who said it, but 60 min is 3600seconds not 360s. A. And B. Yes it will ALWAYS be the EXACT same degree which boils down to 1.2 or something like that. Never the less. The degree will NEVER change bc 1/4”/‘ is a constant no matter how long a run you have. But if you were doing say a 100 footer, you’d use the 2%index.
 
#17 ·
No max pitch in any size under IPC. How would one got vertical?

I understood that at slopes more than 1/4"/ft, the water runs around the 'solids' and the pipe gets clogged more easily, but that is either an old wives tale or good advice from seasoned plumbers, depending on who you listen to. Apparently, the documented upper limits on slope exist to limit velocity in order to prevent erosion (wear) of the pipe walls. The consensus of the sources I read seems to be that good practice is to keep to a 1/4"/ft and then 45 down at the end into the main. Vertical pipes are obviously ok because everything just falls.
 
#19 ·
The part about solids being passed by liquids has been disproven, that is why it is not in the IRC.
 
#29 ·
Hi everyone.

I know my 3 inch horizontal drain has got to be at a 1/4" per foot

My question is..

What would 1/4" per foot be equal to in degrees ?

I've looked on the internet for this answer and I havent had much luck. Your help is appreciated.
This chart I found shows that a 2% slope equals 1.15 degrees. That sound right to me. Here is the link. Calculating Slope and Common Slopes in Architecture