Water Service Sizing and velocities of
Water Service Sizing and velocities of
(OP)
I am having to do more and more water service sizing and am looking for some insight into the maximum velocity that should be used in sizing water services for multifamily. In general a 3/4" service is adequate for a single family and possibly a duplex. Where does one draw the line at velocity and go up a size. Any resources would also be appreciated
Thanks
Mark Oberschmidt
Thanks
Mark Oberschmidt





RE: Water Service Sizing and velocities of
Also, the Uniform Plumbing Code has a method called the "demand fixture unit method" which is very conservative but sometimes required.
If you don't have either reference check with your local plumbing inspector and with the water service provider. They should be willing to let you use their copies for a short time at their offices.
Good luck
RE: Water Service Sizing and velocities of
RE: Water Service Sizing and velocities of
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Canman
RE: Water Service Sizing and velocities of
KRS Services
www.krs-services.com
RE: Water Service Sizing and velocities of
Basic question,
Flow of liquid depends on the velocity and area. If I use 4" sch. 40 C/S Pipe, and keep increasing the velocity (just assume), flow will also increase. Can anyone tell me what is the maximum flow can be achieved from 4" pipe and why there is a limit of maximum flow.
Thanks
RE: Water Service Sizing and velocities of
There is no theoretical limit to the flow. The real limits are: 1 the strength of the pipe material and 2 the energy required to achieve the higher velocity. In the water business the test is the practical one of cost. If you use a small pipe then pumping (energy) costs will be higher. If you use a larger, more expensive, pipe then pipe costs are higher but pumping costs are lower. The "break even" point usually occurs around a velocity between 4 to 6 feet per second. This is a rough rule of thumb but is widely used and has been for many years.
good luck
RE: Water Service Sizing and velocities of
Use the Darcy equation:
h= (fL/D) v*2/2g
where h= head in feet
f= pipe friction factor, assume 0.17
L= pipe length, feet
D= pipe diameter, feet
v= fluid velocity, ft/sec
g= 32.2 ft per sec per sec
RE: Water Service Sizing and velocities of
Reasonable pipe velocities depend on the application. There is no correct velocity for all applications. Here is a general guideline.
Reasonable Velocities for the Flow of Water through Pipe:
Boiler Feed.............8 to 15 ft/sec
Pump Suction ............4 to 7 ft/sec
General Service.........4 to 10 ft/sec
City.......................to 7 ft/sec
Transmission Pipelines...3 to 5 ft/sec
RE: Water Service Sizing and velocities of
Can the joints, even restrained ones, endure 1425 psi? I don't know, I'm just asking, but can't see how.
Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve
RE: Water Service Sizing and velocities of
Be aware that for a given velocity the pressure drop is higher in small pipes than in large ones. This means you can use higher velocities in larger pipes for the same pressure drop.
For example, a velocity of 6 ft/s for water in a 3/4" pipe will give a pressure drop of 14 PSI over 100 ft of pipe. However, in a 4" pipe the same velocity of 6 ft/s gives a pressure drop of only 1.9 PSI over 100 ft. In the 4" pipe you would have to increase the velocity to 16.5 ft/s to get a pressure drop of 14 PSI.
regards
Katmar
RE: Water Service Sizing and velocities of
Maximum allowable pressure ratings of fittings is equal to that computed for straight seamless pipe of equivalent material. Maximum allowable pressure varies directly with the allowable stress. The design pressure is the maximum sustained pressure that a piping system must contain without exceeding its code-defined allowable stress limits.