EXAMPLE $8\mathrm{.}2$

A domestic cold$-$water service system is shown in Figure $8\mathrm{.}8.$ The water main in the street

is $50$ m from the entry point shown and the supply authority provides a minimum static

pressure of $20$ m water gauge. The velocity energy and the frictional resistance at the ball

valve amount to $2$ m water gauge. Determine the pipe sizes.

$230$ I cold$-$water storage tank

$50$ m to water main

Dimensions in metres

Water main head $=20m$

$8\mathrm{.}8$ Cold$-$water service pipe$-$sizing diagram for Example $8\mathrm{.}2.$

EXAMPLE $8\mathrm{.}2$

A domestic cold$-$water service system is shown in Figure $8\mathrm{.}8.$ The water main in the street

is $50$ m from the entry point shown and the supply authority provides a minimum static

pressure of $20$ m water gauge. The velocity energy and the frictional resistance at the ball

valve amount to $2$ m water gauge. Determine the pipe sizes.

$230$ I cold$-$water storage tank

$50$ m to water main

Dimensions in metres

Water main head $=20m$

$8\mathrm{.}8$ Cold$-$water service pipe$-$sizing diagram for Example $8\mathrm{.}2.$The solution is there but my question is why they consider the pressure of the first floor and why the final pipe diameter is $20$ mm$.$ And from where they decided the discharge