Inlet Design

[RJLDesign]

Fellow designers

I am trying to find a little progem that will give me the inlet capsities of a chamber when given the required info.

e.g.

900mm RW pit with 300mm of grate volume removed and 150mm cover.

Either in a DOS based for or excel file

any help be great

Rj

(PS. Im in australia so metric would be a benifit)

 

[tincan]

AustDesigner
I'm afraid something got lost in the translation from Oz to Am. Do you mean a grated curg/gutter inlet 900mm long x ?? wide with approximately 1/3 openings with a 150mm curb??

The US Federal Highway Administration has data on inflow of curb and gutter inlets.

Best, Tincan.

 

[RWF7437]

You may find such a program, but I doubt it. Your best bet is to check with the Federal Highway Administration, in the US or and with your State Highway and local highway departments.

Remember that the inlet grate acts as a weir at low flows and then as an orifice at high flows when there is ponding over the grate. Most grates are not designed, but bought, from an ironworks and come in locally "standard" sizes. Grate manufacturers may also have capacity data so don't overlook them too.

There is little point in designing a grate for a specific flow since you probably will not be able to estimate the flow to within plus or minus 30 percent anyway.

If you're not in the US or Canada, perhaps someone else on this forum can advise you where to look for such data.

good luck

 

[cvg]

most programs I have seen are highly specialized for the particular region they are used. I have also seen spreadsheets used for this purpose. It is fairly easy to program in excel. As Russ stated, for low flows, use the weir equation, with appropriate weir coefficient and the perimeter of the grate (minus the cross bars. For higher flows, use the orifice equation and calculate effective flow area. In between weir and orifice is a transition zone. You will have to interpolate a flow value if depth is within this region. You should assume an appropriate safety factor for plugging of the grate or curb opening. Typically here, we use 50% blockage. This accounts for plastic bags, paper cups, branches or vehicles parked on the inlet which block the flow. Make sure your choice of weir and orifice coefficients are acceptable to the agency approving your designs.

 

[RJLDesign]

not really what im after guys. Im talking about a inlet in a drain or swale.

say a 900mm x 900mm chamber with 300mm taken up with inlet bar.

 

[bltseattle]

Is there a local highway drainage manual? The Washington State Department of Transportation presents different methods in their Hydraulics Manual. Most of the equations come from an FHWA hydraulics manual. Both are available by .PDF online. Your local transportation agency may have a comparable hydraulics manual.

 

[Maury]

Neenah Foundry Co. (Neenah Wis.) did studies of the drainage capacities of their castings, both for intercepted flow in gutters and for ponding conditions.

 

[stanier]

Try Flowpro2. Do a google search for this window based engineering tool. This little gem can be used for all manner of free surface flows and is free. If your kean you can download HEC RAS and fight with that.

No one procrastinated their way to the top

 

[stanier]

Check out this website for a free on line book on flow in channels.

http://www.haestad.com/library/book...avascript/wwhelp/wwhimpl/java/html/wwhelp.htm

Go to the haestad methods website and enter the civil quiz. You could then select as a prize the 10 node culvert master or flowmaster program and use that for your analysis. Buy the book and you might get a 25 node program. Use a discount prize to get $100 off the book.

No one procrastinated their way to the top