flow in pipes

[AHMEDDODO]

dear all
iam so much confused of how much could be a pipe diameter to permit a flow rate of 400 lit/min of slurry from one tank to another, the flow by gravity, and the level differnce betwee the 2 tank is 1 metre and the length of the pipe is 10 metre

 

[Frank1344]

Hello,

have you decided on the material you want to use?
is velocity important to you?
how did you lay out your piping?

your present data is not enough for sizing.

Faraz
Calgary

 

[AHMEDDODO]

dear frank
thank you very much...
i forgot to tell that the pipe is made of upvc,
and the velocity is not that important iam only concerning about flow and the slurry is cold

ahmed assem

 

[TD2K]

If you draw a sketch of the two tanks, it will be clearer.

The head for flow will depend on the level in the two tanks and the elevation differences between the two tanks. With your slurry density, you can convert this to a psi differential. Then, you just need to solve for what pipe diameter with this differential will give you a flow of 400 l/min over a 10' length (don't forget your entrance and exit losses).

Is this just to allow a minimum flow between the two tanks? Do you have to control the flow? What happens as the levels change, is that a concern?

With slurries, you should also check your velocity and make sure you aren't going to have settling issues (sorry, don't have much experience in this field).

If you don't have a copy, Crane's Technical paper 410 is a highly recommended reference.

 

[ddkm]

Guys,

I'm having a similar question in another thread

http://www.eng-tips.com/viewthread.cfm?qid=136432&page=1.

I'll use this particular thread by ahmed to illustrate how I view this sort of problem. Do correct me if I'm wrong.


In my view, he has given sufficient data to SIZE the piping. I would list down as follows:

V, Volumetric flowrate = 400L/min thru gravity

(Somehow he has determined that the slurry will flow at 400L/min thru gravity. I've used this assumption without further questioning the validity)

but V = pi/4*(D^2) v

where v = fluid linear velocity (typical)


From various sites and discussion, at the moment it appears that a "typical" fluid velocity is in the range of about 5ft/s or about 1.5 m/s. [ Can anyone confirm this unequivocally???? ]


Using v = 1.5 m/s

and V = 400L/min = 0.006667 m3/s

we thus get: D = 75.2mm diameter on the piping


i.e. choose standard DN80mm piping.



****************************************


Note: I've NOT considered the losses in the pipe, pressure drop due to viscosity of the slurry, bends in the pipe, overall pipe length etc. As such, I realize my calc above is extremely simplified. But just wanted to verify the BASIS with you guys. Thanks.


---engineering your life---

 

[ddkm]

This is what I got using the

http://www.engineeringpage.com/engineering/line.html

site. I used "Sodium Chloride sol with solids" to represent Ahmed's slurry (rightly or wrongly). Apparently, the site calculates the typical (or max) velocity as 3m/s though.


*********************************************************

CALCULATION INPUT
Selection Criterium Usual maximum velocity for Sodium Chloride (Salt) solution with solids 3 m/s
Flow Data Flowrate 0.006667 m3/s
Pipe data ANSI B36.10, B36.19



------------------------------------------------------------CALCULATION RESULTS
Flowrate 0.0067 m3/s 105.6741 GPM (U.S.)
24.0012 m3/h 847.5944 ft3/h

The smallest suitable Pipe Size is 2.5 inch
External Pipe Diameter 73.02 mm 2.87 inch
Wall Thickness 5.16 mm 0.2 inch
Internal Pipe Diameter 62.7 mm 2.47 inch
Fluid velocity 2.159 m/s 7.084 ft/s

As the above is an unusual size a 3 inch pipe is recommended.
External Pipe Diameter 88.9 mm 3.5 inch
Wall Thickness 5.49 mm 0.22 inch
Internal Pipe Diameter 77.92 mm 3.07 inch
Fluid velocity 1.398 m/s 4.587 ft/s

Note:

The thickness used is the standard wall thickness, no check with respect to the maximum operating pressure was performed.
As this is an unusual size a 3 inch pipe with a diameter of 88.9 x wall thickness of 5.49 is recommended.




---engineering your life---

 

[katmar]

Slurry piping design needs more detail than has been given here. What is the solid loading, the particle and bulk density, flow characteristics, particle sizes etc etc? You need to get a good book and spend a few solid hours learning about this before you commit to a design.

As a starting point you can use the reference at

http://www.cispi.org/handbook/chapter8.pdf

I give this reluctantly, because although this is a very good reference for what it is intended for (i.e. sewage piping) it may not be applicable to your case. And with the limited data you have given I cannot say whether or not it is applicable. The CISPI document shows that with a slope of 1 in 10 you could use a 3" pipe 3/4 full or a 4" pipe half full. In both cases you would have velocities of over 6 ft/sec (assuming water density) and this would certainly keep a sewage pipe clean.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[AHMEDDODO]

hi all

i thank you all for the contribution in solving my problem
and i think i have solved it now

but i would like to ask what else info should i give to you to be full detail??