×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

maximum water depth / diameter in open channel flow

maximum water depth / diameter in open channel flow

maximum water depth / diameter in open channel flow

(OP)
We are checking a roof drainage pipe (30m length- 10" dia) that water depth will be about 75% of the pipe diameter. some codes require 67% max ratio. what is the potential risk of allowing water depth to exceed the code requirement given that the pipe length is only 30m (from the downspout to the sump)

RE: maximum water depth / diameter in open channel flow

The maximum flow rate does not occur under full bore conditions. The maximum discharge occurs when the water depth in circular pipes reaches 93.8% of the pipe diameter.

If you allow the water to back up, you may have a leak on the roof.

RE: maximum water depth / diameter in open channel flow

don't forget about leaves and debris. most roof drains get plenty of that and it really cuts down on the flow capacity of your pipes.

RE: maximum water depth / diameter in open channel flow

Careful. The real danger is ponding on the roof and collapse of the structure.

Learn from the mistakes of others. You don't have time to make them all yourself.

RE: maximum water depth / diameter in open channel flow

At 67% depth you are at 80% of the max flow.
At 75% depth you are at 91% of the max flow... (max flow is at 82% depth)
Then passing from 67% to 75% you divide by 2 the security margin...
With the forecast of stronger storm in coming years, I let you make the calculation of damage versus installing larger pipes.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources