Transcript Slide 1

Environmental Controls I/IG
Lecture 7
Upfeed Systems
Pipe Sizing Procedure
Pipe Sizing Example
Upfeed Systems
Pressure in Upfeed Systems
Fixture pressure head
Static head
Friction head loss
Meter pressure loss
S: p. 913, F.21.13
Pressure in Upfeed Systems
Proper fixture flow pressure
+ Pressure lost due to height
+ Pressure lost due to friction
+ Pressure lost through meter
Total street main pressure
A
B
C
D
E
A: Fixture
Flow Pressure
Pressure
needed to
get water
through
fixture
S: p. 970, T.21.14
B: Pressure lost due to height
Weight of water
column
S: p. 913, F.21.13
C: Pressure loss due to friction
Initially unknown, must be calculated
based on pressure remaining after
accounting for the other factors
D: Pressure lost through meter
Make initial size assumption and
then repeat to optimum size
S: p. 971, F.21.63a
E: Total Street Main Pressure
Check with water company or fire department
Pipe Sizing Procedure
1. Determine
Supply
Fixture
Units
Fixture units
take into
account
usage
diversity
S: p. 974, T.21.15
2. Calculate Demand Flow
Use curve 1 for flush valve dominated system
Use curve 2 for flush tank dominated systems
S: p. 975,
F.21.65a
3. Determine the
“Most Critical Fixture (MCF)”
Highest and
farthest from
inlet main
Confirm
pressure
required (A)
Identify
height (B)
S: p. 958, F.21.52
4. Determine Developed Length
The total length of all
horizontal and vertical
pipes from the main to
the MCF
S: p. 995, F.22.17
5. Determine Total
Effective Length (TEL)
Two approaches:
1. equivalent length
or
2. multiply DL x 1.5
TEL= DL x 1.5
S: p. 976, T.21.16a
6. Determine Street
Main Pressure (E)
Contact utility
company or fire
department
7. Determine Pressure Available for
Friction Loss
Proper fixture flow pressure
+ Pressure lost due to height
+ Pressure lost due to friction
+ Pressure lost through meter
Total street main pressure
or
C=E-A-B-D
A
B
C
D
E
Meter Loss (D)
Since D is unknown, pick an initial
size, do calculation, repeat as
needed to optimize flow
C=E-A-B-D
S: p. 971, F.21.63a
8. Determine Friction loss/100’
C=E-A-B-D
Δp/100’ = 100 x C/TEL
9. Verify flow
for meter size
If flow > Total Demand
(#2)  repeat 7-9 at
smaller diameter
If flow < Total Demand
(#2)  repeat 7-9 at
larger diameter
S: p. 972, F.21.64a
10. Select final
meter size
When flow > Total
Demand (#2)  stop
S: p. 972, F.21.64a
Pipe Sizing Example
Given Information
Small Office Building  public numbers
2 Flush valve toilets
2 Lavatories
2 Drinking fountains
1 Service sink
DL: 92’
MCF: Flush Valve Toilet, 16’ above water main
Street Main Pressure: 44.1 psi
1. Determine
Supply
Fixture
Units
Fixture units
take into
account
usage
diversity
S: p. 974, T.21.15
1. Determine Supply Fixture Units
2 Flush valve toilets
2 Lavatories
2 Drinking fountains
1 Service sink
Cold Hot
20.00
--3.00 3.00
0.50
--2.25 2.25
25.75 5.25
Total
20.0
4.0
0.5
3.0
27.5
2. Calculate Demand Flow
20 WSFU out of 27.5 WSFU are flush valves
Use curve 1 for flush valve dominated system
40 gpm
S: p. 975,
F.21.65a
3. Determine
the Most
Critical
Fixture
Confirm
pressure
required (A)
15 psi
Height above
main (B)
16’  7.0 psi
S. p. 970, T.21.14
4. Determine Developed Length
Developed length
92’
S: p. 975, F.22.17
Note: this figure for generic
reference only and does not
illustrate the example
problem
5. Determine Total
Effective Length (TEL)
TEL= DL x 1.5
= 92 x 1.5
= 138’
6. Determine Street
Main Pressure (E)
44.1 psi
7. Determine Pressure Available for
Friction Loss
Proper fixture flow pressure
+ Pressure lost due to height
+ Pressure lost due to friction
+ Pressure lost through meter
Total street main pressure
A
B
C
D
E
15.0
7.0
?
?
44.1
Meter Loss (D)
Pick an initial size
2” diameter… 1.4 psi
S: p. 971, F.21.63a
8. Determine Friction loss/100’
C=E-A-B-D
= 44.1-15.0-7.0-1.4
= 20.7 psi
Δp/100’=100 x 20.7/138
= 15 psi/100’
9. Verify flow
for meter size
At 2”
Flow=150 gpm >
Total Demand 40 gpm
At 1-1/2”
Flow=60 gpm >
Total Demand 40 gpm
(Δp/100’= 13.1)
At 1”
Flow=13 gpm <
Total Demand 40 gpm
(Δp/100’= 5.1)
S: p. 972 F.21.64a
9. Verify flow
for meter size
When flow > Total
Demand (#2)  stop
At 1-1/2”
Flow=60 gpm >
Total Demand 40 gpm
(Δp/100’= 13.1)
S: p. 972 F.21.64a
Pipe Sizing
Use Δp/100’=
13.1 psi/100’
Use fixture units to
determine flow
S: p. 972 F.21.64a
Pipe Sizing
Use fixture units to
determine flow
Pay attention to flush
valve domination
S: p. 972 F.21.65a
Pipe Sizing
Use Δp/100’=
13.1 psi/100’
Use fixture units to
determine flow
Select size which does not
exceed 13.1 psi/100’
20 gpm, use 1”
10 gpm, use ¾”
Use runout sizes at each
fixture
S: p. 972, F.21.64a
Runout
Pipe Sizing
Use actual flow to size
runouts
Lavatory:
2 gpm
S: p.970, T.21.14
Runout
Pipe Sizing
Use Δp/100’=
13.1 psi/100’
Lavatory: 2 gpm
S: p. 972, F.21.64a
Notation System
Suggested for
organizing data
WSFU Curve
Flow Diam.
2.7 2
3 ½”
S: p. 995, F.22.17
3.6 2
4 ¾”