"n" and "k" values for 6" PVC 2

[drhenne]

I am using a horizontally run section of 6" PVC culvert as the principle outlet for a retention pond. Can anyone provide me with mannings "n" and a "k" value (entrance head loss coefficient - pipe end mitered to match a 3-1 side slope; no headwall protection)? I would also appreciate recommendations of a reliable source of this type of information. I have tables for corregated metal and concrete pipe as well as nearly every other type of channel lining but nothing on PVC. Thank you.

 

[jasmichel]

I am sorry that I don't have an answer for you, but I was wondering if you could provide me with some information on the metal and concrete table that you were talking about in your post. I am having a hard time finding this info, and I need to make my numbers consistent. If you could email me this info, or point me in the right direction, I would really appreciate it.

jasmichel@hotmail.com

 

[n3rei]

I use n=.006 and k=1
CEG

 

[noroc]

The Manning n depends on many factors, such as corrosion, sliming, and joint offsets, which occur in aged sewers. The Manning n for new PVC pipe is 0.009 and a mature pipe can be conservatively estimated at 0.011.

http://www.vylonpipe.com/techsheets/Clay Pipe Flow Comparison.htm

 

[MechanicalJoint]

I typically never use a Mannings' n less than 0.013. Don't forget that most contractor's won't build what you design to "Lab" quality...which is where most of the n values are determined...

For your K values, look for a government document called HY-8. It does a good job of providing K values for various end configurations.

 

[Waterboy]

I don't know of a reference for plastic pipe "n" values, but the lower limit for n is 0.009 (glass tubing). When I worked with the Corps of Engineers, we replaced CMP culverts with 72" PVC pipe and used an n of 0.011. For a mitred entrance with no headwall, the entrance loss coefficient is normally taken as 0.7. This can be confirmed in most any publication dealing with culverts.

 

[mynx]

The manufacturers recommended manning's 'n'is 0.009, however I do not recommend using anything below 0.013 as you are not dealing with pristine conditions. You should allow for additional roughness that will occur as a result of sedimentation, slime etc... not to mention installation tolerances. Normally I don't use anything smaller than an 8" pipe for culverts unless you have restrictions that won't allow for larger diameter. For other inofrmation regarding PVC pipes perhaps try contacting the "UNI-BELL PVC PIPE ASSOCIATION" in Dallas, Texas.