You need to get hold of the local authority regulations. Many are
posted on the Internet. In Australia we have the WSA codes. Failing
that your local authority having such a document try AWWA as they
will have guidelines for the USA.
If you get desperate you could use the Australian standards from
www.wsa.org.
You could also get hold of Haestad's Sewercad to model the system.
regards
Geoff
- In PipingDesign@yahoogroups.com, "Michael Roble" <mroble@...>
wrote:
>
> I've been working on some sanitary drains recently, and I'm pretty
> familiar with calculating the drop across whatever distances I'm
> running. However what I'm curious about is why is there such big
> discrepencies between what everyone says is "standard"?
>
> My main header starts off as a 4", and I hear 1/8" slope is
required,
> and when it gets bigger I was instructed that 1/16" is ok from then
> on. Then as we go on, I hear "Instead of 1/8" use 1' of drop per
> 100'.." which is pretty close to 1/8", (1/8" = .01, and 1' per 100'
> = .012), but then I'm handed a chart printed from the internet
> regarding Manning's equation of 2' per second flow, and it's
telling
> me the factor is like 0.0084 for a 4" and it slopes less and less
as
> you get into larger sizes.
>
> I completely understand that these numbers are probably miniscule
> differences at best, I'm just curious as to why there's so many
> different ways and outcomes to reach a factor? I'm at home now, I
> went to look at the National Plumbing Code today at work, and
someone
> has it signed out, so I'll have to wait to check on that when it's
> returned.
>
> I just figured I'd try to ask what you guys think and what you guys
> normally use.
>
> Any input is greatly appreciated.
>
> Michael Roble
> Piping Designer
> Continental Design And Management Group
> Pittsburgh, PA
>
Received on Fri Feb 01 21:20:00 2008