. In-
stant check valve response prevents unnecessary vent discharge dur-
ing pump "off cycle".
Vent discharges C0
2
gas to atmosphere in the event of fouling or mal-
function of check No. 2 thereby safeguarding the potable water sys-
tem from CO
2
gas contamination. In line design minimizes pressure
drop across the valve thereby assuring maximum pump performance.
FEATURES
Stainless steel body and parts
Instant check valve response
Minimum pressure drop
Triple check protection of the water supply
SPECIFICATIONS
Maximum pressure 150 psi (10.34 bars). Maximum temperature
140
°
F (60
°
C). Suitable for initial pressures up to 150 psi (10.34 bars).
All stainless steel body and heavy duty rubber parts assure the longest
and most dependable operating life. All rubber compounds comply
with FDA food additive regulations.
STANDARDS
Designed to meet the requirements of New York City Health
Code Section 81.47.
NSF Standard No. 25, Revised Items 4.35.2 and 4.35.3.
APPROVALS
Approved by independent testing, completing over 2,000,000
successful pump cycles with positive backflow protection and trouble-
free performance.
All rubber compounds comply with FDA food additive regulations.
ES-9
USA: 815 Chestnut St., No. Andover, MA 01845-6098; www.wattsreg.com
Canada: 5435 North Service Rd., Burlington, ONT. L7L 5H7; www.wattscda.com
HOW IT OPERATES
Static Pressure-No Flow
Primary disc (1) seats
against diaphragm (2)
with diaphragm (2)
sealing off the atmos-
pheric port (3). Secon-
dary disc (4) seals
against downstream seat
(5). Ball check (6) seals
against ball check seat
(7). This is the normal
position taken by the
device when there is no
demand on downstream
equipment.
Valve Opened Flowing
Under Pressure
With flow through valve,
primary disc opens away
from diaphragm seal.
Atmospheric port re-
mains closed by deflec-
tion of diaphragm seal.
Secondary disc opens
away from downstream
seat. Ball check opens
away from ball check
seat permitting flow of
water through valve.
Valve Closed by Back
Pressure in System
With a back pressure
condition created, ball
check seats firmly
against ball check seat.
Secondary disc seals
tightly against down-
stream seat. Primary
disc seals tightly against
diaphragm. Atmospheric
port is now open
permitting air to enter air
break chamber. In the
event of fouling of
downstream check valve,
leakage of CO
2
gas
would be vented to
atmosphere through the
vent port thereby safe-
guarding the potable
water system from CO
2
gas contamination.
This valve should only be used in areas
where spillage of water could not cause
damage. Install a vent discharge line to
the vent outlet of 9BD and vent to a safe
place of disposal with adequate ventilation
where CO
2
discharge is not a hazard.
For Non-Health Hazard Applications
Job Name ____________________________________________
Contractor ______________________________________________
Job Location __________________________________________
Approval _______________________________________________
Engineer _____________________________________________
Contractor P.O. No. _______________________________________
Approval _____________________________________________
Representative __________________________________________
DIMENSIONS - CAPACITY
Water
Supply
Valve
Filter Pump
100 psi
Carbonator
H
2
0 and CO
2
Back Pressure 60-120 psi
CO
2
Gas
Cooler
9BD Backflow Preventer
TYPICAL INSTALLATION
kPa psi
207 30
172 25
138 20
103 15
69 10
35
5
0
0
.5
1
1.5
2.
2.5
gpm
1.9
3.8
5.7
7.6
9.5
lpm
2
3 4
"
2
3
4
6
1
5
7
1
3 8
" ES-9 0014
© Watts Regulator Co., 1997
Printed in U.S.A.
Model NLF9
Vacuum Breakers for
Lab Faucets and
In-Line Applications
Watts NLF9 is a patented backsiphonage
preventer specially made for laboratory faucets
where portable hoses can be attached. Its
purpose is to prevent the flow of contaminated
water back into the potable water supply and can
be intalled on new or existing faucets without
plumbing changes.
APPLICATIONS
NLF9 should be installed on every laboratory outlet where a hose
can be attached. Its unique design provides full protection against
all backsiphonage conditions.
To prevent tampering, it is recommended that the NLF9 be secured
to the laboratory faucet with Loctite.
NLF9 is not designed for continuous pressure applications. For con-
tinuous pressure applications, use N9 Series or
3 8
" 7 shown below.
CONSTRUCTION
NLF9 Is suitable for either hot or cold water service. It features
brass construction and a primary check valve utilizing a soft disc
which seats against a soft rubber mating part to ensure tight clos-
ing. A secondary check valve utilizes a soft disc-to-metal seating.
NLF9 provides better-than-average flow rate and consequently
lower pressure loss. Construction is brass body with polished
chrome plating, stainless steel working parts and durable rubber
diaphragm and disc.
STANDARDS
ANSI/ASSE Standard 1035 - "Laboratory Faucet Vacuum Breakers"
CSA B64.8, UPC
APPROVALS
ASSE, CSA and UPC
PRESSURE/TEMPERATURE
Maximum pressure: 150 psi (10.34 bars)
Maximum temperature: 140
°
F (60
°
C)
Laboratory Faucets
Parlor Sinks
HOW IT OPERATES
NLF9
Size:
3 8
"
Static Pressure-No Flow
Illustration shows NLF9
under pressure but with
no demand on down-
stream equipment. Pri-
mary check (1) seats
against diaphragm (2)
with diaphragm (2) seal-
ing off the atmospheric
ports (3). Secondary
check (4) seals against
downstream seat (5).
Valve Opened Flowing
Under Pressure
With flow through
valve, primary check
opens away from dia-
phragm seal. Atmo-
spheric ports remain
closed by deflection of
diaphragm seal. Sec-
ondary check opens
away from downstream
seat permitting flow of
water through valve.
Valve Closed By Back-
Siphonage in System
With a back-siphonage
condition created, second-
ary check seals tightly
against downstream seat.
Primary check seals tightly
against diaphragm. Atmo-
spheric port is now open
permitting air to enter air
break chamber. In the
event of fouling of down-
stream check valve, leak-
age would be vented to at-
mosphere through the vent
port thereby safeguarding
the potable water system
from contamination.
kPa
psi
207 30
172 25
138 20
103 15
69 10
35
5
0
1
2
3
4
5
6
gpm
0
3.8
7.6
11.4 15.2
19.0 22.8 lpm
DIMENSIONS / WEIGHT / CAPACITY
Model N9
Similar to NLF9 except furnished with
1 4
" or
3 8
" female inlet and outlet
connections, for in-line continuous
pressure applications.
N9
Sizes:
1 4
",
3 8
"
2
3 8
"
1
1 4
"
Weight
6 oz.
2
3
4
1
5
No. NLF9
Hose
Connection
Combination
Fixture
Recommended Strainer
Watts No. 27
Open End, Only
Outlet on Fixture
Hot
Cold
Mixed
Water
Line
3 8
"
Drain
No.
N9
1"
Job Name ____________________________________________
Contractor ______________________________________________
Job Location __________________________________________
Approval _______________________________________________
Engineer _____________________________________________
Contractor P.O. No. _______________________________________
Approval _____________________________________________
Representative __________________________________________
Maximum pressure: 150 psi (10.34 bars)
Maximum temperature: 140
°
F (60
°
C)