Relief Valve Discharge Rates

Typical Flow Rates as
sized by floor drain
manufacturers
Drain
Size
gpm lpm
55 209 2
112 426 3
170 646 4
350 1330 5
2
1
⁄2" – 10" 957
Rate of Flow
Pressure
lpm gpm
1330 350
1140 300
950 250
760 200
570 150
380 100
190 50
0 0
0 20 40 60 80 psi
0 138 276 414 552 kPa
ES-RVD 0904 © Watts, 2009
USA: 815 Chestnut St., No. Andover, MA 01845-6098; www.watts.com
Canada: 5435 North Service Rd., Burlington, ONT. L7L 5H7; www.wattscanada.ca
Water Safety & Flow Control Products
40 80 120 160 200 240 280 3000
900
800
700
600
500
400
300
200
100
0
2
1
⁄2" – 10" 994
Rate of Flow
0 40 80 120 160 200 240 280 psi
0 276 552 827 1103 1379 1655 1931 kPa
Pressure
lpm gpm
3420 900
3040 800
2660 700
2280 600
1900 500
1520 400
1140 300
760 200
380 100
0 0
Note: These curves
represent catastrophic
or worst case discharge
rates. These curves
were developed by pres-
surizing the outlet of
the backflow preventer
with the second check
valve’s internals removed
from the body.
1" 919 RV
Capacity w/Second Check Removed
2" 919 QT
Backpressure w/Second Check
Poppet & Spring Removed
Rate of Flow
Rate of Flow
Pressure
Pressure
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 psi
0 .7 1.4 2.0 2.8 3.5 4.1 4.8 5.5 6.2 6.9 7.8 8.3 9.0 9.7 10.3 11.0 11.7 12.4 bar
0 10 20 30 40 50 60 70 80 90 100 110 psi
0 .7 1.4 2.1 2.8 3.5 4.1 4.8 5.5 6.2 6.9 7.6 psi
lpm gpm
228 60
190 50
152 40
114 30
76 20
38 10
0 0
lpm gpm
684 180
170
6.8 160
570 150
532 140
130
456 120
110
380 100
342 90
304 80
266 70
228 60
190 50
152 40
114 30
76 20
38 10
0 0