Flow in a Pipe
8
flow in a pipe discussion sree555 (Mechanical) 8 Oct 05 3:02 What is the relationship between the pipe or duct diameter and the maximum flow allowed? Check Out Our Whitepaper Library. Click Here . zdas04 (Mechanical) 8 Oct 05 8:57 Interesting question for a mechanical engineer. I'd say that the relationship is described by the Navier-Stokes equation. You can probably find it in your Fluids book or do a Google search. David mbeychok (Chemical) 8 Oct 05 12:16 sree555: There is no equation, formula or relationship that will calculate the "maximum flow allowed" in a pipe. For a given fluid, given pipe diameter, given pipe length and given flow, there is a specific pressure drop. Then it becomes a matter of: (1) Can your system tolerate that pressure drop? If not, then you need a larger diameter. (2) Also, will the linear velocity of the fluid in that given pipe diameter lead to erosion ot some other undesirable effect? If so, then you need a larger diameter. As a very broad generality, these linear fluid velocities are usually found to be acceptable: about 7 feet per second for liquids and about 40-70 feet per second for gases. Milton Beychok (Contact me at www.air-dispersion.com ) . sailoday28 (Mechanical) 9 Oct 05 13:29 Structural and environmental effects should also be considered. High velocities can cause vibrations and noise. A big consideration is the economic impact. Higher pressure might require a thicker wall. High velocity may case errosion and hence a thicker wall. Artisi (Mechanical) 10 Oct 05 1:38 Although everything said so far is correct, I disagree that there is in fact a theoretical but impractical "maximum flow rate" thru a pipe(line), a somewhat pedantic argument but worth mentioning. As the head loss in a pipe(line)increases as the square of the flow rate IE, double
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Flow in a Pipe
Transcript of Flow in a Pipe
flow in a pipe discussionsree555 (Mechanical)
8 Oct 05 3:02
What is the relationship between the pipe or duct diameterand the maximum flow allowed?
Check Out Our Whitepaper Library. Click Here.
zdas04 (Mechanical)
8 Oct 05 8:57
Interesting question for a mechanical engineer.I'd say that the relationship is described by the Navier-Stokes equation.You can probably find it in your Fluids book or do a Google search.
David
mbeychok (Chemical)
8 Oct 05 12:16
sree555:
There is no equation, formula or relationship that will calculate the "maximum flow allowed" in a pipe.
For a given fluid, given pipe diameter, given pipe length and given flow, there is a specific pressure drop. Then it becomes a matter of:
(1) Can your system tolerate that pressure drop?If not, then you need a larger diameter.
(2) Also, will the linear velocity of the fluid in that given pipe diameter lead to erosion ot some other undesirable effect?If so, then you need a larger diameter.
As a very broad generality, these linear fluid velocities are usually found to be acceptable:about 7 feet per second for liquids and about 40-70 feet per second for gases.
Milton Beychok(Contact me at www.air-dispersion.com).
sailoday28 (Mechanical)
9 Oct 05 13:29
Structural and environmental effects should also be considered.High velocities can cause vibrations and noise.A big consideration is the economic impact.Higher pressure might require a thicker wall.High velocity may case errosion and hence a thicker wall.
Artisi (Mechanical)
10 Oct 05 1:38
Although everything said so far is correct, I disagree that there is in fact a theoretical but impractical "maximum flow rate" thru a pipe(line), a somewhat pedantic argument but worth mentioning.
As the head loss in a pipe(line)increases as the square of the flow rate IE, double the flow increases the head by a factor of 4, a point is reached where irrespective of what pressure you apply to the flow - no appreciable increase in flow will ensure - so, at some point prior to this the maximum flow is reached. However, good engineering practice is to analyse the flow/ head loss/costs of the pipe line /the pumping system and the operating costs for the most economical solution.
Naresuan UniversityPhitsanulokThailand
25362 (Chemical)
10 Oct 05 1:55
When dealing with steam visit
thread378-98039
sree555 (Mechanical)
10 Oct 05 2:44
How to reduce the total dissolved salts in water for industrial usage? For example the water with 7000ppm TDS and a total hardness of 2000ppm as to be reduced to 2000ppm TDS and the total hardness to 600ppm? How to go about it withot Reverse Osmosis?
sailoday28 (Mechanical)
10 Oct 05 2:49
Artisi, Continuing with your reasoning, what happens (const friction factoran non flashing-incompressibleflow of course) as the pipe diameter increases? Head decreases in the ratio of D^3.Regards
Artisi (Mechanical)
10 Oct 05 3:52
I think you will find that as pipe diameter increases head decreases as D^5
Naresuan UniversityPhitsanulokThailand
25362 (Chemical)
10 Oct 05 10:04
It seems to me all depends on the value of the friction factor f. The general formula states that
Pf is proportional to f (L/D)(V2)
and
f = f (Re, /D)
/D is the rugosity ratio expressing the pipe's surface relative roughness; Re is the Reynolds number.
When looking at the Moody diagram one gets the impression that
Pf ~ k1/D4for highly turbulent flows (Re>106) in smooth tubes (/D
