hydraulic values for asbestos cement pipe

[mungerUEI]

I am using the Hazen-Williams equation to calculate flow in existing A.C. pipe: 12" and 8". What should I use for an actual inner diameter?
Also, what is a reasonable value for the Hazen-Williams "C"? I don't know exactly when the pipe was installed, but the fact that it's A.C. gives an indication.

 

[BigInch]

If you must use Hazen Williams (see thread164-165987) and you have an existing system, it should be easy enough to work out the true C values, even with two pipe diameters, assuming you know the lengths of each one. It will be a lot better than looking for C values that may fit your data ... or may not.

You really should model the pipeline using two segments, one for the 8" and another segment for the 12". And use some real flow equation too, but if you really don't want to do that for some reason, then use HW with the equivalent pipe method to combine the head loss of the two different diameter pipes into 1 total head loss for the total length. Start with a reasonable value for C, calculate the equivalent diameter. Ratio the total head loss using velocity^2 in each segment x segment_Length/total_length, check by calculating the head loss in each segment and adjust C until the sum of each individual segment head loss equals the known total head loss.

I think that should do it, but I'm a bit on the sleepy side right now and my RC mouse is acting up and its really beginning to irritate me, so I'll have to see if the above still looks good in the morning.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[BigInch]

In the meantime look down to thread164-183006

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com