Zurn wilkins 720A User Manual

Model 720A

Pressure Vacuum Breaker

(1/2", 3/4", 1", 1 1/4", 1 1/2" & 2")

 Installation  Testing  Maintenance Instructions

INSTALLATION INSTRUCTIONS

®

CAUTION: Installation of Pressure Vacuum breakers must be performed by qualied,

licensed personnel. Faulty installation could result in an improperly functioning device.
The installer should be sure the proper device has been selected for the particular installation.
ZURN WILKINS Model 720A Pressure Vacuum Breakers are for use on irrigation, industrial,
and other non-potable services where a health hazard could exist if a backsiphonage situ­ation were to occur. They must not be installed where backpressure may occur.
Proper performance depends upon following these installation instructions and prevailing
governmental and industry standards and codes. Failure to do so releases ZURN WILKINS
of any liability that it might otherwise have with respect to that device. Such failure could
also result in an improperly functioning device.

1. Before installing the ZURN WILKINS Model 720A Pressure Vacuum Breaker, ush the

lines thoroughly to remove all debris, chips and other foreign matter.

2. The Model 720A must be installed in a vertical position (see Fig. 1) to provide
proper operation of the air inlet valve.

3. Provide adequate space around the installed unit so that the test cocks will be
accessible for testing and servicing.

4. CAUTION: If installation of a Model 720A unit is in a building, provide a suit-

able drain arrangement to drain off spillage from the air vent.

5. Install valve at least 12 inches above the highest piping or water outlet down
stream of the Model 720A Pressure Vacuum Breaker.

6. Always consult local codes for installation methods, approvals and guidance.

7. The Model 720A Pressure Vacuum Breaker may be installed outdoors only if the
device is protected against any freezing conditions. Warning: do not block air vent
opening with insulation. Exposure to freezing conditions will result in improper
function or damage to the device. The installation location must be kept above 32°F.

PLACING THE DEVICE IN SERVICE

After the installation of a Model 720A Pressure Vacuum Breaker has been completed, place
the unit in service as follows:

1. Start with both shut-off valves and test cocks closed. Open the inlet shut-off valve until the
Pressure Vacuum Breaker is completely pressurized.

2. A brief discharge from the air vent may occur while the device is pressurizing. The
discharge should cease by the time the shut-off valve is in the full open position.

Fig 1

MAIN SHUT-OFF
VALVE (1)

INLET DRAIN
VALVE (2)
(If allowed by
local codes)

TESTCOCKS (4)

DRAIN

DIRECTION OF FLOW

1” 720A PVB
(25MM)

INLET
SHUT OFF
VALVE (3)

OUTLET SHUT OFF
VALVE (5)

OUTLET DRAIN
VALVE (6)

TO IRRIGATION
SYSTEM

3. If the discharge does not stop, refer
to "MAINTENANCE INSTRUCTIONS".
Repressurize device as in Step 1. Device
should function properly.

4. Slowly open the No. 2 shut-off valve.
The Model 720A is now in service.

5. After the Model 720A has been prop­erly installed, test the device. If the device
fails the test, refer to "MAINTENANCE
INSTRUCTIONS"

Drain Procedure for Freeze Protection

1. Turn off main shut-off (1) that supplies
water to the system.

2. Open both inlet and outlet drain valves
in the system (2 & 6). Open inlet and outlet
shut-off valves on the pressure vacuum
breaker (3 & 5) and all of the test cocks.
Leave all valves and test cocks in the half
open/half closed (45°) position to allow full
drainage of the ball valves and test cocks.

3. If you "blow out" the system down­stream of the pressure vacuum breaker,
make sure the outlet drain valve (6) is open
and the pressure vacuum breaker shut-off
valve (5) is closed.

4. Connect an air hose to the outlet drain
valve (6) and inject an adequate volume of
air to remove all water from the downstream
portion of the system.

5. CAUTION: Open outlet shut-off valve to
the pressure vacuum breaker (5) and outlet
drain valve (6) to the half open/half closed
(45°) position after "blow out" process is
completed.

6. If drain valves (2 & 6) are not part of
the system, and if air pressure is not used
to "blow out" the system, the internal com­ponents of the pressure vacuum breaker
should be removed for the duration of the
winter.

7. Leave all drain valves (2 & 6), shut-off
valves (3 & 5) and test cocks in the half
open/half closed position (45°) for the
duration of the winter to prevent freezing.
Caution: Be certain that main shut-off (1)

remains tightly closed to prevent relling of

the system. Also, the main shut-off valve
must be resilient seated to insure no leak­age of water into the system.

WARRANTY: ZURN WILKINS Valves are guaranteed against defects of material or workmanship when used for the services recom­mended. If in any recommended service, a defect develops due to material or workmanship, and the device is returned, freight prepaid,
to ZURN WILKINS within 12 months from date of purchase, it will be repaired or replaced free of charge. ZURN WILKINS' liability shall
be limited to our agreement to repair or replace the valve only.

Proposition 65 Warning This product contains chemicals known to the State of California to cause cancer or birth defects
or other reproductive harm.

In accordance with U.S. Federal Safe Drinking Water Act Lead-Free requirements, as of January 4, 2014, this product can only be used in water sys­tems considered non-potable. Please contact your local water utility for further requirements.

Maintenance

1. Close inlet and outlet shut-off valves before disassembling device.

2. Remove canopy screws counterclockwise and remove canopy.

3. Bleed off pressure by opening the No. 2 test cock.

4. Unscrew the bonnet from the body by turning counterclockwise.

5. Remove the disc & poppet assembly, check spring and spider assembly from body.

6. Clean all parts with clean water only.

7. After completing inspection, replace necessary parts and reassemble. Repair kits are available from your supplier.

8. Retest according to "TEST PROCEDURES".

Testing Procedures

TEST NO. 1

Purpose: To test the opening pressure dif­ferential of the air inlet valve.
Requirement: The air inlet valve shall open
when the pressure in the body is no less than

1.0 psi above atmospheric pressure. The air
inlet valve shall be fully open when the water
drains from the body.

STEPS:

1. Bleed water through both test cocks
to eliminate foreign material.

2. Install appropriate ttings for test kit

hoses.

3. Remove air inlet valve canopy.

4. Install the high side hose of the differ­ ential pressure gauge to test cock #2.
Open test cock #2 and bleed air from
hose and gauge.

5. Close #2 shut-off valve then close #1
shut-off valve.

6. Slowly open the high side bleed needle
valve being especially careful not to
drop the pressure differential too fast.
Record the pressure differential at which
the air inlet valve opens.

7. Close test cock #2 and remove equip­ ment.

8. Open #1 shut-off valve.

TEST NO. 2

Purpose: To test the check valve for tightness

in the direction of ow.

Requirement: The check valve shall be drip-

tight in the normal direction of ow when the

inlet pressure is 1.0 psi and the outlet pres­sure is atmospheric.

STEPS:

1. Attach high side hose of differential
gauge to test cock #1. Open test cock
#1 and bleed all air from the hose and
the gauge by opening high side bleed
needle valve. Close high side bleed
needle valve.

2. Close #1 shut-off valve.

3. Open test cock #2. The air inlet valve
will open and the water in the body will
drain out through test cock #2.

When this ow of water stops, the dif-

ferential pressure indicated by the
gauge after it has settled will be the
pressure drop across the check valve.
This value must be 1.0 psi or greater.
Record this value. If water continues

to ow out of test cock #2, then the #1

shut-off valve is leaking.

4. Close test cocks #1 and #2 and remove
equipment.

5. Replace air inlet valve canopy.

6. Open #1 shut-off valve, then #2 shut­ off valve.

CANOPY

SCREW

BONNET

O-RING

SPRING

BALL VALVE

TEST COCK#2

CANOPY

PLASTIC
WASHER

DISC &
POPPET ASSY

SPIDER
ASSY

BODY

TEST COCK#1

BALL VALVE

Troubleshooting

PROBLEM

Air inlet valve does not open as gauge drops to 0.0 psid.

Air inlet valve does not open and differential on gauge will
not drop.

Air inlet opens below 1.0 psid.

Check valve opens below 1.0 psid.

2

IS720A (REV. 4/13)

POSSIBLE CAUSES

1. Air inlet disc stuck to seat.

2. “Old Style” pressure vacuum breaker (non-loaded air
inlet valve).

1. Leaking No. 1 shut-off valve.

2. Parallel installation with leaky No. 2 shut-off valve.

1. Dirty or damaged air inlet disc.

2. Scale buildup on seat.

1. Dirty or damaged air inlet disc.

2. Damaged seat.

ZURN WILKINS

1747 Commerce Way, Paso Robles, CA 93446 Phone:[phone] Fax:[phone]

www.zurn.com

®