Dear Sadegh,

The following is the required equation:

  

 MHd = (BO1 + BO2 + 2CL)/ [theta x (pi/180)].



Where:

MHd = Manhole Diameter, inches

BO = Blockout Diameter, inches

CL = Minimum Concrete Leg Length, inches (6 inches)

Theta = Angle between pipe centerlines, degrees

For more details, please see attached file.

Hoping this will be helpful,

Rafik

Thanks a lot professor, but it is manhole diameter. i want equation for speed of water in the manhole to find from that variation of water-depth in the manhole...thanks for your attention

Ask your question from Dr. Fazlollah Saqravani

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Dear Sadegh,

The attached paper might be helpful.

Rafik

Dear Rouhollah Aminnia, thanks for your guidance...

Dear professor Rafik Karaman, thanks a lot for your attention...