OT - Pipe volume

[bob farrell]

Would someone do me a big favor and help with a simple math problem. Need to know the formula for figuring the volume of a 4 inch ID pipe, 10 feet long. Forgot the formula and can't find my ninth grade math book. Things used to be a lot simpler. Thanks ! bob farrell

 

[JMS MN]

Area equals pi r squared. Volume equals area times length.

 

[phillip d]

Area of a circle is a=pie times radius squeared,if I remember right.So that being said,volume= lengthxwidthxheight.4/2=2,2x2=4.4(radius squeared)x3.14=12.56 cubic inches per foot.12.56/1 =1.0466666 cubic feet per linier foot,x10 feet long should=10.466666 cubic feet in your 10' long piece of 4" pipe.Just my rusty math,If I'm wrong,I'm sure someone will correct me lol.pd

 

[Gene Dotson]

No, No, pie aren't square, Pie are round. Got two in the freezer to prove it!!!

Merry Christmas.... Gene

 

[JDemaris]

I'm a math moron, but still remember that -
Pi (3.14) times R (radius) square equals area.

That figure times length equals volume.

That comes to 1,522 cubic inches or 10.63 cubic feet.

 

[Bob]

.
The

 

[Bus Driver]

Cornbread are square.

 

[super99]

How come pies can't be square? I can see lots of advantages, all the middle pieces don't have crust to contend with. You got to admit, there are a few good crusts floating around out there, but most are aweful! Chris

 

[Gun guru]

4" X 4" X .7854 = 12.56 X 120" =
120" is 10 feet by the way.

 

[Bill(Wis)]

Corn muffins, on the other hand, are usually round, or are they pi? Or is it called "pie" because it is round? (pi)? Do you remember if it was the chicken or the egg that came first?

 

[Dan-IA]

Wouldn't that be an 8 inch pipe? I thought volume was area times length, and area uses the radius instead of a diameter.

 

[bob farrell]

Bob - Hate to be a moron - but when using the calculator for my example the radius would be 2(inches) and the length would be ?? (10 feet OR 120 inches) ?? bob f.

 

[Steven f/AZ]

(quoted from post at 11:59:57 12/23/07) How come pies can't be square? I can see lots of advantages, all the middle pieces don't have crust to contend with. You got to admit, there are a few good crusts floating around out there, but most are aweful! Chris

I'd love a square pie, as I'm not a fan of any type of crust. Pie=good, Pi=3.1415927

 

[Anonymous-0]

There are 231 cubic inches in a gallon so taking 1,508 cubic inches and dividing by 231 equals 6.528 gallons.

 

[JMS MN]

I've heard of chicken pot pie,...........and you need the egg for the meringue!

 

[tg in VA]

Hey Gun Guru, explain ".7854" I calculate it to be
pi/4. Why did you use it instead of pi x r squared to find the area? Just curious, I"ve never seen it done that way.

 

[bob farrell]

Steve - As I recall - you are a teacher? Would you please answer my question. Maybe take me through the formula. I know it is simple but I guess age is about to get me (70 pretty quick). I really need to know how many cubic feet is in a 4 inch by 10 foot piece of pipe. Thanks ! bob f.

 

[Iowa_tire_guy]

I vote for 10.476 cubic feet.

 

[Anonymous-0]

From my Dowell Engineering Tables:
4 inch ID = .6528 gallons/ft

Unlike all the smart as answers given below.

 

[Jim James]

I have an easier way as far as I am concerned. Any time you need volume of a pipe, tank or anything round, Covert the diameter to inches and take inches times inches times .0408 and the answer will be gallons per foot. Then you can multiply by the length or height or break it down by inches. Example a 5 foot diameter tank 12 feet tall is _________ gallons.
60 times 60 equal 3600 times .0408 equal 146.88 gallons per feet times 12 feet heigh equal 1,762.56 gallons.
I learnt this in my water and wastewater classes and have used nothing but it since. alot easier to me than the pie or .7854??

 

[Jim James]

4 times 4 equal 16 times .0408 equal .6528 gallons per feet times 10 equal your pipe holds 6.528 or 6 and half gallons of water.

 

[Gun guru]

Nope. D (squared) X .7854 = 12.56 in^2

 

[bob farrell]

Jim - Thanks. You are trying to help. Would the cubic feet of air then be 0.8689 (6.5 gallons times 231 cubic inches per gallon)?? Thanks bob f.

 

[Anonymous-0]

Get you one these little books and all your math problems will disappear if you can flip to the right page.

 

[George G]

I could never remember what pi was, so, I always used .7854. Just remember to push point first then 7854 are in the upper left corner of your calculator,easy to remember. So you would go D x D x.7854=area x length (in inches)= cubic inches /1728 = cubic feet.(4 x 4 x .7854 = 12.5664
Sq. in. . 12.5664 x 120 = 1507.968 cubic inches / 1728 = .8726 cubic feet.
.7854 is the area (in sq. inches) of a 1 inch ID circle.

 

[bob farrell]

George G. _ Thanks for the reply. I kept coming up with less than a cubic foot in a ten foot pipe and it just didn't seem right. Your answer confirms. Thanks a bunch to the others that replied (even those that weren't too funny). Seems the older I get the harder it is to come up with the right answers. Thanks again ! Bob Farrell

 

[MarkB_MI]

Gun guru,

Why bother using .7854? All you're doing is hiding the "pi x r squared" formula we all learned in grammar school. Look:

Area = pi * radius^2

and

radius = diameter / 2

So:

Area = pi * (diameter / 2) ^2
= pi * (diameter^2) / 4
= (pi/4) * diameter^2
= (3.1415 / 4) * diameter^2
= .7854 * diameter^2

So you haven't gained anything by using .7854 instead of pi. Other than now you have to remember two numbers (pi for diameter, .7854 for area) instead of one. Unless, of course, you just remember that you need to divide pi by 4 to get this magic number. But I'd just as soon divide the diameter by two as divide pi by four, because the diameter is usually a round number, while pi is not.

 

[tiresntracks]

I'm not sure why, but I have to jump in to this discussion.
Pi(3.1416)x radius(2)squared(4)=12.5664 x length(120")=1508 cubic inches. 1508 divided by 231(cu. in. per gallon)=6.528 gallons. How'd I do?

 

[Gun guru]

Your right, but in vocational tech class that is the way I learned it. I think of it as 78.4% of a square.

 

[Jerry/MT]

Volume of a circuar cylinder is = pi/4 x ID^2 x Length, where pi =3.14159... will give you the volume in consistant unit, i.e the length and the ID have to both be in inches or both be in feet, etc and then the volume is in cubic inches or cubic feet respectively.

 

[kyplowboy]

I never figured that one out. When I went for the class to get my license as "Water Plant Operator" the day they covered math I walked out when the teacher started using the .7854. Took me years of school"n to get pi x r(sq) I was not going to learn a new one. Asked him bout it later and he said most people never learned it is school or forgot it and it was easier to teach 30+ year olds the .7854 way insted of try"n to explain what pi was. Diffrent strokes of difrent folks I guess.

Dave

 

[George G]

You say "pi for diameter". I don't get it. I alreddy know that the pipe is 4 inch ID. What's pi got to do with that ? If I want to know the area, I just multiply dia. x dia. x .7854 = sq.in (4 x 4 x .7854 =12.5664).
The magic number .7854 is the area of a 1 inch diameter circle.
Most, if not all hydraulics and pneumatics courses teach this method.

 

[Mark]

The farmer sent his boy off to college and when the boy returned home...the Farmer asked him:
Son, what did you larn down thar at thet thar collitch?

The boy said: Well, Paw, I learned Pi R Square.

The Farmer replied: I shoulda knowed I wasted my money...any damned fool knows pie are round.

 

[MarkB_MI]

Sorry George, I meant to say "pi for circumference", not "pi for diameter". I'm assuming that you need to calculate circumference every now and then.

I guess if the only calculation you ever need to make is area, this works. But to me it just obfuscates a very simple formula.