cheet sheet for velocities in pipes

[jebbo2]

I currently have a sheet that FDOT provides which will give you overland velocities for certain landuses and slopes. I am wondering if anyone might have the same available for pipes?

 

[glennd]

jebbo2:

the limiting velocities in pipes is more restricted by the pipe lining material and the available head to create the velocity in the first place.

I am unsure what the FDOT suggests but here in victoria, australia the limts go up to 4m/s. Velocities over abut 2.5m/s should be looked at carefully as suspended materials may erode the pipe walls and create a pipe failure. If you have a steep pipe and are trying to lose the available head, try using a drop pit instead.

 

[PBroad]

Jebbo2,
You may find that cheat sheets died when we closed up our sliderules in favour of progammable calculators. At one time almost every pipe supplier had some form of quick identification charts. One supplier I still find useful, though 30 years old on hydraulics is from Johns Manville Sewer pipe manual TR572C 10-71 (back then it was $10). It gives gravity flow in full bore pipes for concrete (c100) and steel (c140) pipe dependant on the slope. Another rule of thumb helper is to measure the flow in a pipe based on the discharge profile. Water exiting a horizontal pipe dips and if you measure the point where it has fallen 4" you can calculate flow ie if water from a 10" pipe projects 12" before falling 4" the flow is 1850usgpm. its based on the equation Q=X * (1.28Dsquared). All dimensions are id which matters little on steel pipe but very sig. on HDPE.

For more modern info perhaps there is something on the Californian Engineers Club website that may help. See

http://www.engineers.com/software/software

They have lots of free shareware for engineers and the NPS piping database may be what you need.

Happy hunting, get back to me if I can help further.

 

[KRSServices]

jebbo,

If you are looking for a handy dandy cheat sheet for open pipe systems, I have just the ticket. IPEX has a very neat little slide unit that once the n value, slope and flow, velocity is the output. The beauty is that by inputing various data changes, any value can be derived. For example, total flow. I would caution against velicities which would promote scour. If open channel or ditch, I the RTAC Publication - Drainage Manuals #1 and #2. They are vary condensed and provide some very good nomograpghs for varying condidtions....as a quick check in your design.

 

[PECPESC]

Here is a good item. It is a plastic circular slide rule.
It does pipes, ducts, sewers & open channel.

Have used one for years for Q & D (quick & dirty) answers.

http://www.sliderules.clara.net/collection/specialised/9918-mears-hyd.htm