Years ago while attending apprenticeship school, with Local 2, My Instructor gave me a formula for figuring out the amount of air left in an airchamber after the system was wet. It had something to do with volumes and pressures.
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Plumbing Math
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Re: Plumbing Math
Boyles law ..need to know,volume of the airchamber,and absolute pressure....pressure and volume are inversely proportional,to find the volume of a charged airchamber,it would be say 14.7 psi,over say 12 cu. in.,at 65 psi of static pressure the volume would then be 2.213 cu in,but as any plumber knows,the volume of air in a nonsealed airchamber,after any given amount of time is zero.

Re: Plumbing Math
That is the one thing that the union would have exposed me to..More of the formulas for figuring different situations to ease installation and layout.Picked up a few over the years.
Something I would like to learn is the rolling 45 degree offset.Straight 45 offset I was taught my first year.
Where would a plumber apply the amount of volume in a chamber.Medical,industrial?I have tried to see where I would use this in my scope of work in commercial.Can't see anything yet.
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Re: Plumbing Math
rolling offset is:
This works when the angle between your roll and rise is 45 degree
Roll(sq.) + Rise(sq.) + Run(sq.) = Travel(sq.)
If your angle is not equal to 45 degree the formula is 2 steps
rise(sq.) + run(sq.) = roll(sq.)
Then, Roll(sq.) + Rise(sq.) + Run(sq.) = Travel(sq.)
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Re: Plumbing Math
You mean you guys don't stand under the pipe, waving your tape measure all around, squinting one eye and then have the apprentice cut a piece about say 15" long, Ok take an inch off, another 1/2, just a shave, Damn it's too short now.
I tell my apprentices that if they can calculate offsets and rolling offsets they can do something better than half the masters in this state can't.sigpic
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Re: Plumbing Math
Originally posted by NHMaster3015 View PostYou mean you guys don't stand under the pipe, waving your tape measure all around, squinting one eye and then have the apprentice cut a piece about say 15" long, Ok take an inch off, another 1/2, just a shave, Damn it's too short now.
I tell my apprentices that if they can calculate offsets and rolling offsets they can do something better than half the masters in this state can't.
Sometimes a guy could get a small job done faster by just measureing and cutting. It didn't matter to themmeasure center to center then start figuring.
So if you don't mind my asking whats a rolling offset?
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Re: Plumbing Math
If you lay two 45's on the ground I call that a straight offset(I don't know the correct terminology).Easy,as you can just measure the center to center of the offset and multiply by Masterplumb's 1.41 then take off for your fittings.
Some times you need to roll your 45's off the same plane to get from point A to point B,a rolling offset.
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Re: Plumbing Math
Originally posted by bigPipe09 View Postrolling offset is:
This works when the angle between your roll and rise is 45 degree
Roll(sq.) + Rise(sq.) + Run(sq.) = Travel(sq.)
If your angle is not equal to 45 degree the formula is 2 steps
rise(sq.) + run(sq.) = roll(sq.)
Then, Roll(sq.) + Rise(sq.) + Run(sq.) = Travel(sq.)
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Re: Plumbing Math
Remember that since the math is derived from the Phyagorean theorum (A squared plus B squared = C squared) all the measurments are taken from the center line. You need to have a manufacturers chart to get the make in allowance whic in turn needs to be subtracted from the actual pipe length. There are constants you can use for 22's, 60's 72's also. After you get all that down you can move on to paralell offsets and rolling offsets and paralell rolling offsets.sigpic
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Re: Plumbing Math
Originally posted by NHMaster3015 View PostRemember that since the math is derived from the Phyagorean theorum (A squared plus B squared = C squared) all the measurments are taken from the center line. You need to have a manufacturers chart to get the make in allowance whic in turn needs to be subtracted from the actual pipe length. There are constants you can use for 22's, 60's 72's also. After you get all that down you can move on to paralell offsets and rolling offsets and paralell rolling offsets.
OK now I'm glad I've become a service plumber and bidet advocate and spokesperson. My gosh all the floor joists and studs and basement walls would be full of my tabulations If I knew how to do all that.
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Re: Plumbing Math
Alright guys, please hang in here with me, I learn faster in person/hands on, it's hard for me to understand this over the internet. I just laid out some fittings on the street.
A neighbor walked by and probably thought I was high on something laying pvc fittings out in the street at 8:30 at night, and measuring the air in between them.
When you guys talk about off sets, if this what your referring too?
Would the center to center measurement times 1.5 work with a lay out like this?
I tried and tried and couldn't get it to work out right.Proud To Be Union!!
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