Municipal Systems and Building Installations_assigment_ZI_2015

Residential water installation design

Building Installations and Municipal Systems

Assignment 1:

Zsuzsa Iwanicka

[email protected]

Desing principle:

Water main's pressure must be great enough to overcome all local

and linear resistances due to friction in pipe length, wall

irregularities, number of fittings and net vertical distance traveled

while still delivering the required pressure at the remote outlet.

Low water pressure

Water supply pressure in a residential or commercial building should not fall below 0,05MPa at the point of

use. When pressure drops below this point, common

appliances and plumbing fixtures will no longer function

properly.

Source: http://www.ecosilesia.com

Task

Count the minimal pressure in the water main, that ensures proper operation of the installation without using additional pressure

booster.

Steps:

1. Calculate the flow rates for the particular pipe segments

2. Size the water pipes

3. Determine the water pressure drop for pipe segments

4. Select a water meter and anti-pollution valve

5. Calculate pressure drop for the hydraulically most remote fixture

Flow rates in water distribution system

qn maximum flow [dm3/s] - depends on the fixture type

Fixture qn

Sink faucet: 0,07 dm3/s

Shower head: 0,15 dm3/s

Bathtube faucet: 0,15 dm3/s

Toilet: 0,13 dm3/s

Washing machine: 0,25 dm3/s

This is the title

Source: Gd K. Sanitary Installation lecture notes

Minimal pressure in the water main - pmin

gh hydrostatic pressure

h vertical height difference between fixture and water main

water density = 1000kg/m3

g acceleration due to gravity g=9,81m/s2

pmeter pressure drop on water meter

pap pressure drop on anti-pollution valve

ptot pressure losses of all of the piping, valves, elbows, etc.

preq discharge pressure at the fixtures

kPa]or [Pa ,min reqtotapmeter pppphgp

qm - maximum probable flow [dm3/s]

Residential and office buildings:

Hotels and shopping centers:

Use qm to calculate the pipe diameter

ssq

sqq

n

nm

/dm 5,0q and /dm 201,0

/dm ,12,0698,0

3

n

3

35,0

ssq

sqq

n

nm

/dm 5,0q and /dm 2007,0

/dm ,14,0682,0

3

n

3

345,0

Water pipe sizing

dt - pipe diameter (theoretical) [m]

qm - maximum probable flow [m3/s]

Vd - water velocity, m/s,

Vd = 1,0 m/s service line, horizontal pipes,

Vd = 1,5 m/s risers

Pipes have fixed diameters -> Select a pipe

Vr - real water velocity

di - inner pipe diameter [m]

[m]

4d

mt

V

qd

[m/s] 4

2i

mr

d

qV

Calculate the linear pressure drop - pL

p - pressure loss [Pa]

- friction factor (a number without dimension)

- density of water [kg/m3]

V - flow velocity [m/s]

di - pipe diameter [m]

l - pipe length [m]

R - pressure drop coefficient Pa/m

R - depends on the pipe material, values are in nomograms or hydraulic

tables

Pa, , lR 2

V

d

lp

2

i

L

Pressure drop caused by local resistances - ploc

Local resistances occur at elbows, tees, valves, diameter changes etc.

Each element has its own flow resistance coefficient:

In practice for water installations pressure drop at local element is expressed by coefficient A. Its value depends on the pipe material.

The smoother inner wall the higher the A value

Pa, , lRA 2

Vp

2

loc

A= 0.3 for steel A =0,51,0 for plastic pipes

The total pressure drop occuring in the pipe segment:

Pa l,RA)(1 p tot locL pp

Steel pipe nomogram

qm [dm3/s]

PEX nomogram

Linear pressure loss coefficient for cold water pipes

Flow rate qm [dm3/s]

PP nomogram part 1

PP nomogram part 2

Determine the water pressure drop for pipe segments

Segment nr

Sqn qm di Vr R l Rl (1+A)*Rl

dm3/s dm3/s mm m/s dPa/m m kPa kPa

1 0,15 0,15 15 0,85 160 3,5 5,6 7,3

2 0,22 0,21 15 1,16 300 1 3,0 3,9

3 0,35 0,29 20 0,91 150 4,5 6,8 8,8

4 0,42 0,32 20 1,02 150 1,5 2,3 2,9

5 0,55 0,38 20 1,21 200 4,5 9,0 11,7

6 1,02 0,55 25 1,12 107 2 2,1 2,8

7 1,14 0,58 32 0,73 35 4 1,4 1,8

8 1,14 0,58 40x3,7 0,70 24 12 2,9 4,3

Source: Gd K. Sanitary Installation lecture notes

Water meter selection

It is based on the service line flow rate. In order to protect the water meter:

/h][m 7.0

max 3mmeterq

Q

Source: www.powogaz.com.pl

Water meter catalogue

Source: www.powogaz.com.pl

Pressure drop on water meter pmeter

Important!

1. Use qm to determine pmeter

2. Convert qm to m3/h!

Anti-pollution check valve

Protects the water main against pollution in a result of back-flow from the installation.

Source: www.ferro.pl

Pressure drop on the anti-pollution pap valve

To determine pap:

1. Take qm for the service line

2. The same di as water meter

Source: www.ferro.pl

Calculate pressure drop for the hydraulically most remote fixture

Fixture Segments h *g*h ptot pmeter pap preq pmin

m kPa kPa kPa kPa kPa kPa

F 1, 2, 3, 4, 5, 6, 7, 8 5,60 55 43,5 40 20 100 258,5

O 9, 3, 4, 5, 6, 7, 8 5,40 53 34,5 40 20 50 197,5

D 16, 4, 5, 6, 7, 8 2,80 27 25,5 40 20 100 212,5

L 15, 11, 10, 6, 7, 8 2,80 27 35,9 40 20 100 222,9

M 13, 12, 11, 10, 6, 7, 8 2,80 27 41,9 40 20 100 228,9

N 18, 7, 8 2,60 25 9,1 40 20 100 194,1

kPa]or [Pa ,min reqtotapmeter pppphgp

. The highest pmin value indicates the hydraulically most remote fixture

The minimal pressure in the water main, that ensures proper operation of the installation without using additional pressure booster is 263.9 kPa.

Fixture Segments h *g*h ptot pmeter pap preq pmin

m kPa kPa kPa kPa kPa kPa

F 1, 2, 3, 4, 5, 6, 7, 8 5,60 55 43,5 40 20 100 263,9

O 9, 3, 4, 5, 6, 7, 8 5,40 53 34,5 40 20 50 202,7

D 16, 4, 5, 6, 7, 8 2,80 27 25,5 40 20 100 215,7

L 15, 11, 10, 6, 7, 8 2,80 27 35,9 40 20 100 226,1

M 13, 12, 11, 10, 6, 7, 8 2,80 27 41,9 40 20 100 232,1

N 18, 7, 8 2,60 25 9,1 40 20 100 197,1