area= 3.14 x radius x radius. so the 6 inch pipe has cross section
of 100 sq inches and the two 4 inch pipe have 25 sq inches
On Mon, 04 Jul 2005 06:21:31 -0500, wrote:

I want to put a drain pipe under a sidewalk for rain drainage. I am
trying to determine the volume of a 6 inch pipe and a 4 inch. I know
that one 4 inch wont be enough, but am wondering if TWO 4 inchers
carry as much or more water than a 6 inch pipe. I have never been any
good at mathematics. I think I have to multiply 4 or 6 by 3.14, but I
am not sure. I will either use a 6 inch or two 4 inchers, which ever
holds more water. Or I may even go to an 8 incher. Alot of water runs
down the hill and keeps putting mud over the sidewalk. I need lots of
drainage volume.

Can anyone help.

bill wrote:

area= 3.14 x radius x radius. so the 6 inch pipe has cross section
of 100 sq inches...

We learn something new every day here...

Nick

Bill you used diameter instead of radius. It is more like 27 sqin for the 6
inch pipe and 12 sqin for the 4 inch pipe not counting the small change.
Also about 48 sqin for the 8 inch pipe. Way more than using 2 of the 4 inch
pipes.

"bill" wrote in message
news
area= 3.14 x radius x radius. so the 6 inch pipe has cross section
of 100 sq inches and the two 4 inch pipe have 25 sq inches
On Mon, 04 Jul 2005 06:21:31 -0500, wrote:

I want to put a drain pipe under a sidewalk for rain drainage. I am
trying to determine the volume of a 6 inch pipe and a 4 inch. I know
that one 4 inch wont be enough, but am wondering if TWO 4 inchers
carry as much or more water than a 6 inch pipe. I have never been any
good at mathematics. I think I have to multiply 4 or 6 by 3.14, but I
am not sure. I will either use a 6 inch or two 4 inchers, which ever
holds more water. Or I may even go to an 8 incher. Alot of water runs
down the hill and keeps putting mud over the sidewalk. I need lots of
drainage volume.

Can anyone help.

wrote in message
Can anyone help.

Pi r2 That does not show up properly but it is Pi (3.1416) x the radius
squared.

wrote:
bill wrote:


area= 3.14 x radius x radius. so the 6 inch pipe has cross section
of 100 sq inches...


We learn something new every day here...

Nick

And what we learned is that Bill gave the correct
formula and then made the simple mistake of
substituting diameter for radius and then not
thinking about what the range for the answer would
be. No criticism of Bill is intended as we all
make mistakes, but what most people don't do is
then consider if the answer makes sense.

For example, a simple 6 x6 grid of inch squares
has 36 square inches. Slap a 6" diameter pipe
down on the grid and the pipe won't cover it, so
you know the answer has to be less than 36 square
inches (no where near 100 square inches). Using
the same logic a 10" pipe wouldn't have 100 square
inches of area. By the same token a 4" pipe can't
have an area of more than 16 square inches.

Actually it is the 4" pipe is 2x2x3.14= 12.6
and 6" pipe is 3x3x3.14= 28.3

The answer is that a single 6" pipe has a larger
area than two 4" pipes.

Sorry for being pedantic, but a simple
visualization is often all that is needed to
realize an error in a mathematical problem.

wrote in message
...
I want to put a drain pipe under a sidewalk for rain drainage. I am
trying to determine the volume of a 6 inch pipe and a 4 inch. I know
that one 4 inch wont be enough, but am wondering if TWO 4 inchers
carry as much or more water than a 6 inch pipe. I have never been any
good at mathematics. I think I have to multiply 4 or 6 by 3.14, but I
am not sure. I will either use a 6 inch or two 4 inchers, which ever
holds more water. Or I may even go to an 8 incher. Alot of water runs
down the hill and keeps putting mud over the sidewalk. I need lots of
drainage volume.

Can anyone help.

Assume similar pipe types such as tile or concrete and a slope that is the
same for both the 4-inch and the 6-inch pipes.

The maximum (pipe full) flow for the 6-inch pipe will be about 15 percent
greater than for the pair of 4-inch pipes.

I computed on the basis of Manning's Formula. I'll spare you the details
but you can Google it if you're curious. Been a long time since I did a lot
of that as a young engineer so I checked a nomogram in one of my old
handbooks and got verification. Interesting exercise but I had to scrape
through a lot of mental rust.

SJF

On Mon, 04 Jul 2005 19:01:32 GMT, in alt.home.repair Pipe
diameter volume "George E. Cawthon"
wrote:

Actually it is the 4" pipe is 2x2x3.14= 12.6
and 6" pipe is 3x3x3.14= 28.3

The answer is that a single 6" pipe has a larger
area than two 4" pipes.

And the 6" pipe will be less likely to clog than the two 4" pipes.

--
To reply to me directly, remove the CLUTTER from my email address.

Yes the single 6" pipe has slightly more area than two 4" pipes


but................

how much water shed area (roof and / or ground) are you draining with
this pipe?


I drain ~800 ft^2 of roof & another 800ft^2 of yard with a single 4"
line. The line drops about 20" over ~130 ft.

This setup handles almost all the various levels of rainfall I get in
SoCal. This year we had nearly 36" of total rainfall with some REALLY
heavy , in the 2" per hour range. With the soil at or close to
saturation, all this needed to be drained.

I did experience some flooding (temporary pooling) due to poor local
soil slope but the water would generally drain off in a few minutes
(10 min) after the downpour let up.

How water your pipe(s) can handle is a function of the size, type &
drop of the pipe.

IMO for most common residential applications a single 4" line should
work............but it depends on how much water your need to drain &
how quickly.

cheers
Bob

IMO simplest circular section area formula...............area = D * D
*.7854
..7854 = Pi/4

because we tend to measure & think about diameters

"SJF" wrote in message
news:xljye.3475$HV1.1917@fed1read07...
wrote in message
...
I want to put a drain pipe under a sidewalk for rain drainage. I am
trying to determine the volume of a 6 inch pipe and a 4 inch. I know
that one 4 inch wont be enough, but am wondering if TWO 4 inchers
carry as much or more water than a 6 inch pipe. I have never been any
good at mathematics. I think I have to multiply 4 or 6 by 3.14, but I
am not sure. I will either use a 6 inch or two 4 inchers, which ever
holds more water. Or I may even go to an 8 incher. Alot of water runs
down the hill and keeps putting mud over the sidewalk. I need lots of
drainage volume.

Can anyone help.

Assume similar pipe types such as tile or concrete and a slope that is the
same for both the 4-inch and the 6-inch pipes.

The maximum (pipe full) flow for the 6-inch pipe will be about 15 percent
greater than for the pair of 4-inch pipes.

I computed on the basis of Manning's Formula. I'll spare you the details
but you can Google it if you're curious. Been a long time since I did a
lot
of that as a young engineer so I checked a nomogram in one of my old
handbooks and got verification. Interesting exercise but I had to scrape
through a lot of mental rust.

SJF

Quick calculation ---pi/4 washes out: Area of a 6" pipe-6^2=36. Area of two
4" pipes is 2*4^2=32.
36/32=1.125--so 6' pipe has about 12.5% more flow area than two 4' pipes.
Just agreeing with your numbers--mental exercise for me too g
MLD

And, now it falls to me to give you pi in the face.

=====================
Has anyone had time to calculate pi beyond the first 4 BILLION places? They
did it with the aid of a computer in the eighties, but after that, I don't
know.



Because everybody needs an accurate pi:
3.141592653589793238462643383279502884197169399375 10582097494459230781640628
620899862803482534211706
79821480865132823066470938446095505822317253594081 28481117450284102701938521
105559644622948954930381
96442881097566593344612847564823378678316527120190 91456485669234603486104543
266482133936072602491412
73724587006606315588174881520920962829254091715364 36789259036001133053054882
046652138414695194151160
94330572703657595919530921861173819326117931051185 48074462379962749567351885
752724891227938183011949
12983367336244065664308602139494639522473719070217 98609437027705392171762931
767523846748184676694051
32000568127145263560827785771342757789609173637178 72146844090122495343014654
958537105079227968925892
35420199561121290219608640344181598136297747713099 60518707211349999998372978
049951059731732816096318
59502445945534690830264252230825334468503526193118 81710100031378387528865875
332083814206171776691473
03598253490428755468731159562863882353787593751
95778185778053217122680661300192787661119590921642 01989380952572010654858632
788659361533818279682303
01952035301852968995773622599413891249721775283479 13151557485724245415069595
082953311686172785588907
50983817546374649393192550604009277016711390098488 24012858361603563707660104
710181942955596198946767
83744944825537977472684710404753464620804668425906 94912933136770289891521047
521620569660240580381501
93511253382430035587640247496473263914199272604269 92279678235478163600934172
164121992458631503028618
29745557067498385054945885869269956909272107975093 02955321165344987202755960
236480665499119881834797
75356636980742654252786255181841757467289097777279 38000816470600161452491921
732172147723501414419735
68548161361157352552133475741849468438523323907394 14333454776241686251898356
948556209921922218427255
02542568876717904946016534668049886272327917860857 84383827967976681454100953
883786360950680064225125
20511739298489608412848862694560424196528502221066 11863067442786220391949450
47123713786960
95636437191728746776465757396241389086583264599581 33904780275900994657640789
512694683983525957098258
22620522489407726719478268482601476990902640136394 43745530506820349625245174
939965143142980919065925
09372216964615157098583874105978859597729754989301 61753928468138268683868942
774155991855925245953959
43104997252468084598727364469584865383673622262609 91246080512438843904512441
365497627807977156914359
97700129616089441694868555848406353422072225828488 64815845602850601684273945
226746767889525213852254
99546667278239864565961163548862305774564980355936 34568174324112515076069479
451096596094025228879710
89314566913686722874894056010150330861792868092087 47609178249385890097149096
759852613655497818931297
84821682998948722658804857564014270477555132379641 45152374623436454285844479
526586782105114135473573
95231134271661021359695362314429524849371871101457 65403590279934403742007310
578539062198387447808478
48968332144571386875194350643021845319104848100537 06146806749192781911979399
52061419663428
75444064374512371819217999839101591956181467514269 12397489409071864942319615
679452080951465502252316
03881930142093762137855956638937787083039069792077 34672218256259966150142150
306803844773454920260541
46659252014974428507325186660021324340881907104863 31734649651453905796268561
005508106658796998163574
73638405257145910289706414011097120628043903975951 56771577004203378699360072
305587631763594218731251
47120532928191826186125867321579198414848829164470 60957527069572209175671167
229109816909152801735067
12748583222871835209353965725121083579151369882091 44421006751033467110314126
711136990865851639831501
97016515116851714376576183515565088490998985998238 73455283316355076479185358
932261854896321329330898
57064204675259070915481416549859461637180270981994 30992448895757128289059232
332609729971208443357326
54893823911932597463667305836041428138830320382490 37589852437441702913276561
809377344403070746921120
19130203303801976211011004492932151608424448596376 69838952286847831235526582
13144957685726
24334418930396864262434107732269780280731891544110 10446823252716201052652272
111660396665573092547110
55785376346682065310989652691862056476931257058635 66201855810072936065987648
611791045334885034611365
76867532494416680396265797877185560845529654126654 08530614344431858676975145
661406800700237877659134
40171274947042056223053899456131407112700040785473 32699390814546646458807972
708266830634328587856983
05235808933065757406795457163775254202114955761581 40025012622859413021647155
097925923099079654737612
55176567513575178296664547791745011299614890304639 94713296210734043751895735
961458901938971311179042
97828564750320319869151402870808599048010941214722 13179476477726224142548545
403321571853061422881375
85043063321751829798662237172159160771669254748738 98665494945011465406284336
639379003976926567214638
53067360965712091807638327166416274888800786925602 90228472104031721186082041
900042296617119637792133
75751149595015660496318629472654736425230817703675 15906735023507283540567040
38674351362222
47715891504953098444893330963408780769325993978054 19341447377441842631298608
099888687413260472156951
62396586457302163159819319516735381297416772947867 24229246543668009806769282
382806899640048243540370
14163149658979409243237896907069779422362508221688 95738379862300159377647165
122893578601588161755782
97352334460428151262720373431465319777741603199066 55418763979293344195215413
418994854447345673831624
99341913181480927777103863877343177207545654532207 77092120190516609628049092
636019759882816133231666
36528619326686336062735676303544776280350450777235 54710585954870279081435624
014517180624643626794561
27531813407833033625423278394497538243720583531147 71199260638133467768796959
703098339130771098704085
91337464144282277263465947047458784778720192771528 07317679077071572134447306
057007334924369311383504
93163128404251219256517980694113528013147013047816 43788518529092854520116583
934196562134914341595625
86586557055269049652098580338507224264829397285847 83163057777560688876446248
24685792603953
5277348030480290058760758251



For those morbidly curious, assuming this number is correct, that's pi
to 6000 decimal places.

Note that pi to 50 places allows you to calculate the circumference of
the universe (assuming you have accurate measurements) in electron
diameters, with several decimal place accuracy.





====================

--

Christopher A. Young
Learn more about Jesus
www.lds.org
www.mormons.com


wrote in message
...
bill wrote:

area= 3.14 x radius x radius. so the 6 inch pipe has cross section
of 100 sq inches...

We learn something new every day here...

Nick

The inside diameter of a pipe should not exceed the outside diameter,
otherwise the hole will be on the outside of the pipe. Seriously though,
another way of figuring the area of a circle is that it will be about
78.5% of that of a square the same size as the circle's
diameter,regardless of whether it is an inch or a mile. Larry

replying to MLD, Rick Rayfield wrote:
lot

Quick calculation ---pi/4 washes out: Area of a 6" pipe-6^26. Area of two 4"
pipes is 2*4^22. 36/32=1.125--so 6' pipe has about 12.5% more flow area than two
4' pipes. Just agreeing with your numbers--mental exercise for me too g MLD

Most of the answers address the problem presented. But the question asked was
about the "volume"of the four and six inch diameter pipes. Roughly, with a
cross section of 12 square inches, a foot of four inch diameter pipe has 144
cubic inches, or 1/12 cubic foot.The six pipe has a rough cross section of
about 27 square inches, or about 1/5 cubic foot per foot of pipe. Or simply,
the six inch pipe for the same length has a volume of a bit more than twice
the volume of the four inch pipe. Last time I looked, four inch pipe is a lot
less than half the price of six inch pipe. So if cost or distributing the
flow are factors, the smaller pipe(s) may be the better answer.



--
posted from
http://www.homeownershub.com/mainten...ume-65969-.htm

On 05/18/2016 3:44 PM, Rick Rayfield wrote:
replying to MLD, Rick Rayfield wrote:
lot

Quick calculation ---pi/4 washes out: Area of a 6" pipe-6^26. Area of
two 4" pipes is 2*4^22. 36/32=1.125--so 6' pipe has about 12.5% more flow area
than two 4" pipes....

....

Most of the answers address the problem presented. But the question
asked was about the "volume"of the four and six inch diameter pipes. Roughly, with a
cross section of 12 square inches, a foot of four inch diameter pipe has
144 cubic inches,...[rest elided for brevity]

But the volume is simply Area * Length so the length also cancels out if
ratio so the volume ratio is identically the cross-sectional area.

Precise numbers are easily available from pipe tables online...

http://www.engineeringtoolbox.com/ansi-steel-pipes-d_305.html

--

On Wednesday, May 18, 2016 at 5:28:33 PM UTC-4, dpb wrote:
On 05/18/2016 3:44 PM, Rick Rayfield wrote:
replying to MLD, Rick Rayfield wrote:
lot

Quick calculation ---pi/4 washes out: Area of a 6" pipe-6^26. Area of
two 4" pipes is 2*4^22. 36/32=1.125--so 6' pipe has about 12.5% more flow area
than two 4" pipes....

...

Most of the answers address the problem presented. But the question
asked was about the "volume"of the four and six inch diameter pipes. Roughly, with a
cross section of 12 square inches, a foot of four inch diameter pipe has
144 cubic inches,...[rest elided for brevity]

But the volume is simply Area * Length so the length also cancels out if
ratio so the volume ratio is identically the cross-sectional area.



Plus the math test ended 10 years ago.

On 05/18/2016 5:18 PM, trader_4 wrote:
....

Plus the math test ended 10 years ago.

Sure (albeit I didn't look figured probably was old given it showed up
w/o a initial subject), but the ill-advised comment wasn't.

--