Freeze Protection Instructions

Proposition 65 Warning This product contains chemicals known to the State of California to cause cancer
or birth defects or other reproductive harm.
Model 350 & 375
Double Check Valve Backow Preventer 3/4" - 2"
Reduced Pressure Principle Backow Preventer 3/4" - 2"
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IS350&375BOF (REV 7/09)
Blow Out / Flush Procedure for Freeze Protection
WARRANTY: 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 WILKINS within 12 months
from date of purchase, it will be repaired or replaced free of charge. WILKINS liability shall be limited to our agreement to repair or replace the
valve only.
To Blow Out System for freeze protection, use the
following procedure:
1. Turn off main shut-off valve (1) that supplies water to the
system.
2. Open inlet drain valve in the system (2). Open inlet and
  outletshut-offvalvesonthebackowpreventer(3&5) 
and all of the test cocks (4). 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. Removeblackbackowpreventerhousing.Replacewith
  orangeblowout/ushtting.Storebackowpreventer 
housing in a safe location for winter. Orange blow out
  ushttingmayremaininvalvebodyduringwinter.Place
plugs in ports to keep debris from entering housing.
 4. Ahosecanbeconnectedtoushoutport(7)todrain 
water to a safe drain.
5. Connect an air hose to the air inlet connection (6). Inject
an adequate volume of air to remove all water from the
downstream portion of the system. Do not allow the
  ttingtooverheat.
6. Leave drain valve (2), shut-off valves (3 & 5) and test
cocks (4) in the half open/half closed position (45°) for
the duration of the winter to prevent freezing.
7. Store valve housing/check assemblies, clamp/sleeve and
o-rings in sealed plastic bag during winter to prevent
weathering.
To Flush System during installation, use the following
procedures:
 1. Installbackowdeviceinpipesystem,leavewateroff. 
 2. Removetheblackbackowpreventerhousingfromthe
bronze body.
 3. InstalltheorangeBlowOut/Flushttingintothebronze
body.
4. Thread a garden hose adapter into Flush-Out port (7).
Connect a hose to the adapter and run to a safe drain.
Shut-off valves (3) and (5) should be open.
 5.Turnonwatersupplyatmainshut-offvalve(1)toush 
out any debris in the pipe. Turn water off.
 6. RemoveorangeBlow-Out/Flushttingandreplace
black check housing back into the line. Close shut-off
valves (3) and (5). Turn water on at main shut-off (1).
 7.Slowlyopenshut-offvalve(3)topressurizebackow 
preventer. Once fully open, pressurize system by slowly
opening shut-off valve (5).
CAUTION: For freeze protection be certain that main shut-off valve
(1)re-mainstightlyclosedtopreventrellingofthesystem.Also,
the main shut-off valve must be resilient seated to insure no leak-
age of water into the system.
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INLET
SHUT-OFF
VALVE (3)
DIRECTION OF FLOW
DRAIN
DRAIN
TEST COCK (4)
OUTLET SHUT-OFF
VALVE (5)
INLET DRAIN (IF ALLOWED BY LOCAL CODES)
VALVE (2)
MAIN SHUT-OFF
VALVE (1)
MODEL 375
MODEL 350
LEAVE BALL VALVES AND
TEST COCKS 1/2 OPEN TO
PREVENT FREEZE DAMAGE
FLUSH OUT-
HOSE
HOSE TO AIR
COMPRESSOR
AIR INLET
BLOW OUT
CONNECTION (6)
BLOW OUT/
FLUSH FITTING
FLUSH OUT
PORT (7)
CHECK
HOUSING
TO SAFE
DRAIN
CHECK
HOUSING
BLOW OUT/
FLUSH FITTING
(ADAPTERS AND HOSES
PROVIDED BY OTHERS)
FLUSH
3/4" DC
WILKINS 350
AIR
INLET
WILKINS
3/4” NPT
3/4” NPT