CALEFFI 573 Series User manual

Function
This dual check backflow preventer with intermediate atmospheric
vent is designed to protect drinking water systems from the return,
caused by backsiphonage or backpressure, of contaminated fluids.
The Caleffi 573 series FlowShield™DuC-AV is certified by ICC-ES
to be in compliance with the International Plumbing Code (IPC),
International Residential Code (IRC), Uniform Plumbing Code (UPC),
and standards ASSE 1012-2021, and CSA B64.3-94. Additionally,
it is also complies with NSF/ANSI/CAN 372, low lead, as certified
by ICC-ES, Drinking Water System Components – Lead Content
Reduction of Lead in Drinking Water Act, California Health and Safety
Code 116875 S.3874, Reduction of Lead in Drinking Water Act.
Product range
573 Series FlowShield DuC-AV
dual check backflow preventer with atmospheric vent
size ½”- ¾” NPT female threaded connection with union
size ½” sweat connection with union
size ½" press connection with union
Technical specifications
Connections: ½”- ¾” NPT female with union
½” SWT with union
½" press with union
Materials: Body: low lead brass
Filter: stainless steel
Check valve: PSU
Check valve stem: brass
Diaphragm: peroxide-cured EPDM
Seals: peroxide-cured EPDM
Maximum working pressure: 175 psi (12 bar)
Maximum working temperature: 210°F (99°C)
Emergency back pressure temperature: 250°F (121°C)
Medium: water
Certified to: ASSE 1012-2021, by ICC-ES, file PMG-1359.
CSA B64.3-94, file 219199.
NSF/ANSI/CAN 372-2011, Drinking Water System Components-Lead Content
Reduction of Lead in Drinking Water Act, California Health and Safety Code 116875
S.3874, Reduction in Drinking Water Act, as certified by ICC-ES, file PMG-1360.
1
ASSE 1012
USC
38517.10
© Copyright 2023 Caleffi
www.caleffi.com
FlowShield™DuC-AV
Backflow preventer with intermediate atmospheric vent
573 Series

2
SAFETY INSTRUCTION
WARNING: This product can expose you to chemicals including lead, which
is known to the State of California to cause cancer and birth defects or other
reproductive harm. For more information go to www.P65Warning.ca.gov.
CAUTION: All work must be performed by qualified personnel trained in the
proper application, installation, and maintenance of systems in accordance
with all applicable codes ordinances.
CAUTION: If the backflow preventer is not installed, commissioned and
maintained properly, according to the instructions contained in this manual, it
may not operate correctly and may endanger the user.
CAUTION: Make sure that all the connecting pipework is water tight.
CAUTION: When making the water connections, make sure that the backflow
preventer connecting pipework is not mechanically over-stressed. Over time
this could cause breakages, with consequent water losses which, in turn,
could cause harm to property and/or people.
Caleffi shall not be liable for damages resulting from stress corrosion, misapplication or
misuse of its products.
This safety alert symbol will be used in this manual to draw attention to safety related
instructions. When used, the safety alert symbol means ATTENTION! BECOME ALERT!
YOUR SAFETY IS INVOLVED! FAILURE TO FOLLOW THESE INSTRUCTIONS
MAY RESULT IN A SAFETY HAZARD.
CAUTION: Water temperatures higher than 100 degrees F can be dangerous.
During the installation, commissioning and maintenance of the backflow
preventer, take the necessary precautions to ensure that such temperatures
do not endanger people.
CAUTION: In the case of highly aggressive water, arrangements must be
made to treat the water before it enters the backflow preventer, in accordance
with current legislations. Otherwise, the valve may be damaged and will not
operate correctly.

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CONSIGNE DE SÉCURITÉ
AVERTISSEMENT: Ce produit peut vous exposer à des produits chimiques
comme le plomb, qui est connu dans l’État de Californie pour causer le
cancer, dommages à la naissance ou autre. Pour plus d’informations rendez-
vous www.P65Warnings.ca.gov.
AVERTISSEMENT: Tous les travaux doivent être effectués par du personnel
qualifié formé à la bonne application, installation et maintenance des
systèmes conformément aux codes et règlements locaux.
AVERTISSEMENT: Si Disconnecteur n'est pas installé, mis en service et
entretenu correctement, selon les instructions contenues dans ce manuel, il
peut ne pas fonctionner correctement et peut mettre en danger l'utilisateur.
AVERTISSEMENT: S'assurer que tous less raccordements sont étanches.
AVERTISSEMENT: Lorque vous effectuez les raccordements d'eau, assurez-
vous que lat tuyauterie reliant disconnecteur n'est pas mécaniquement des
overstressed. Au fil du temps, ceci pourrait causer des ruptures, avec
pour conséquence des pertes en eau qui, à leur tour, peuvent causer des
dommages à la peopriété et/ou les gens.
Caleffi ne pourra etre tenue responsable des dommages resultant de la corrosion, d’une
mauvaise utilisation ou une mauvaise utilisation des produits.
Ce symbole d’avertissement servira dans ce manuel à attirer l’attention sur la sécurité
concernant instructions. Lorsqu’il est utilisé, ce symbole signifie. ATTENTION! DEVENEZ
ALERTE ! VOTRE SÉCURITÉ EST EN JEU ! NE PAS SUIVRE CES INSTRUCTIONS PEUT
PROVOQUER UN RISQUE DE SECURITE.
AVERTISSEMENT: Les temperatures de l'eau supérieure à 100 degrés peut
être dangereux. Au cours de l'installation, mise en service et l'entretien de la
disconnecteur, prendre les précautions nécessaires afin de s'assurer que de
telles températures ne compromettent pas les gens.
AVERTISSEMENT: Dans le cas de l'eau fortement agressifs, des dispositions
doivent être prises pour traiter l'eau avant qu'elle ne pénètre dans le
disconnecteur, conformément à la législation actuelle. Sinon las soupape
pourrait être endommagée et ne fonctionnent pas correctement.

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Flow rate graph
10
2 5
10
5
20 50
Dp (psi)
G(l/min) (
gpm
)
20
10
5
(psi) (bar)
20
1 0.5 10 2 5 15
1
0.52
0
.3
Cv = 0.7
VENT
Δ
Δp (psi) Δp (psi) (bar)
G (l/min) (gpm)

Installation
The 573 Series FlowShield DuC-AV backflow preventer with atmospheric vent must be installed
in accordance with the diagrams contained in this instruction manual taking into account all the
applicable Codes and Regulations.
Before installing, the system must be thoroughly flushed to remove impurities or any debris which
may have accumulated during installation. Failure to remove dirt or debris may affect performance
and the manufacturer’s guarantee.
The 573 Series FlowShield DuC-AV backflow preventer must be installed preferably horizontally
and following the flow direction indicated by the arrow on the valve body.
It also must be installed with one isolating valve and a strainer upstream and one isolating valve
downstream.
The 573 Series FlowShield DuC-AV backflow preventer must be installed in an accessible location
to facilitate testing and servicing.
It must be installed with the vent port connected via an air gap to a discharge line, in accordance
with the plumbing code requirements and keeping a minumum distance of 12” from the floor.
Do not install where the discharge can could cause damage.
If field testing is required by code, it must be installed in accordance with the relevant diagram in
this instruction manual.
NOTE:
When installing the 573 series FlowShield DuC-AV with sweat tailpieces, sweat the tailpiece to the
pipe before installing the body which includes an embedded o-ring.
5

Installation diagram
6
Installation diagram
BACKFL
O
W
PRE
V
Series:
5
73
Sizes:
1/2”
-
S/
N
VEN T
BACKFL
O
W
PREV
Series:
5
73
Sizes:
1/2”
-
S/
N
VENT
Heating system application
BACKFL
O
W
PRE
V
Series:
5
73
Sizes:
1/2”
-
S/
N
VENT
Field testing installation
SUPPLY
Inlet test
valve
Upstream
shut-off
valve
Y-strainer Upstream
test valve
573 series
FlowShield
DuC-AV
backflow
preventer
Downstream
test valve
Downstream
shut-off valve
SUPPLY
Air gap
Vent
Drain
Floor

Field testing procedure
1) Check operation of the discharge. When inlet water pressure drops to atmospheric, the valve
must open the vent port and discharge the contained amount of water in the valve body.
a. Close shutoff valves upstream and downstream.
b. Open the upstream test cock
The water contained in the body must be discharged, indicating that the diaphragm has opened
the vent port.
2) Check for tightness of the internal second check valve. When backpressure is applied to the
downstream side of the valve, the internal second check valve must close back drip tight on its seat.
a. Close shutoff valves upstream and downstream.
b. Open the upstream test cock
c. Install a removable bypass hose connecting inlet test cock to downstream test cock and open
them for admitting pressure to the downstream side of the internal second check valve. Water must
not drip from the vent port indicating that the second check valve is not leaking.
Service
A replacement body assembly, 573100A, is available for order.
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8
NOTES
Caleffi North America, Inc.
3883 West Milwaukee Road
Milwaukee, WI 53208
T: 414.238.2360 F: 414.238.2366
09-2023
For Technical Support call 1-414-338-6338, or
email techsupport.us@calef.com