frictional resistance within a cold water pipework system is influenced most by what?

[dubberz25]

what is frictional resistance within a cold water pipework system influenced most by the:

a: pipework material
b: pipework diameter
c: Number of elbows in the pipework
d:Number of bends in the pipework

Please advice me as i need advice on this subject - thanks in advance.

[fizzput]

Elbows, eg 15mm on elbow = 0.9m if memory is deserting me...

[Alanka]

The pipe diameter has by far the most influence on total flow resistance -- the smaller the higher the resistance.

Pipe material should not make much difference, because at most flow rates there is a static film of water adhering to the inner pipe surfaces. So the friction is caused by faster-flowing water layers rubbing against slower-flowing water layers, rather than water rubbing against the pipework surfaces.

Bends and elbows add to the resistance, with 'slow' bends (i.e. larger bend radius) having less effect than tight 'knuckle' elbows.

[HTB]

Looks like an exam question. I would answer c.

[fuzzy]

they all afect resistance, but yes the bottom line is increase pipe size! look in bs6700 or JTL's level 3 plumbing book, the calcs in there