Watts 757 Series User manual

Series 757, 757DCDA
Double Check Valve Assemblies
Double Check Detector Assemblies
Sizes: 21⁄2" – 10" (65 – 250mm)
• Installation
• Service
• Repair Kits
• Maintenance
For field testing procedure, send for IS-TK-DL, IS-TK-9A,
IS-TK-99E and IS-TK-99D.
For other repair kits and service parts, send for PL-RP-BPD.
For technical assistance, contact your local Watts representative.
757 OSY
IMPORTANT: Inquire with governing authorities for local installa-
tion requirements.
NOTE: For Australia and New Zealand: Pipeline strainers
should be installed between the upstream shutoff valve and the
inlet of the backflow preventer.
Its important that this assembly be tested periodically in com-
pliance with local codes, but at least once per year or more as
service conditions warrant. If installed on a fire sprinkler sys-
tem, all mechanical checks, such as alarm checks and back-
flow preventers, should be flow tested and inspected internally
in accordance with NFPA 13 and NFPA 25.
RP/IS-757/757DCDA
Limited Warranty: Watts Regulator Company warrants each product to be free from
defects in material and workmanship under normal usage for a period of one year from
the date of original shipment. In the event of such defects within the warranty period, the
Company will, at its option, replace or recondition the product without charge. This shall
constitute the sole and exclusive remedy for breach of warranty, and the Company shall
not be responsible for any incidental, special or consequential damages, including without
limitation, lost profits or the cost of repairing or replacing other property which is dam-
aged if this product does not work properly, other costs resulting from labor charges,
delays, vandalism, negligence, fouling caused by foreign material, damage from adverse
water conditions, chemical, or any other circumstances over which the Company has no
control. This warranty shall be invalidated by any abuse, misuse, misapplication or
improper installation of the product. THIS WARRANTY IS IN LIEU OF ALL OTHER WAR-
RANTIES, EXPRESS OR IMPLIED, INCLUDING ANY IMPLIED WARRANTIES OF MER-
CHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Any implied warranties that
are imposed by law are limited in duration to one year.
Some States do not allow limitations on how long an implied warranty lasts, and some
States do not allow the exclusion or limitation of incidental or consequential damages.
Therefore the above limitations may not apply to you. This Limited Warranty gives you
specific legal rights, and you may have other rights that vary from State to State. You
should consult applicable state laws to determine your rights.

2
Guidelines
Most field problems occur because dirt and debris present in
the system at the time of installation becomes trapped in the
#1 check. The system should be flushed before the backflow
valve is installed. If the system is not flushed until after the
backflow valve is installed, remove both check modules from
the valve and open the inlet shutoff to allow water to flow for a
sufficient time to flush debris from the water line. If debris in the
water system continues to cause fouling, a strainer can be
installed upstream of the backflow assembly.
Watts models 757 and 757DCDA may be installed in either
horizontal or vertical position as long as the backflow assembly
is installed in accordance with the direction of the flow arrow
on the assembly and the local water authority approves the
installation. The assembly should be installed with adequate
clearance around the valve to allow for inspection, testing and
servicing. 12" should be the minimum clearance between the
lower portion of the assembly and the floor or grade.
Horizontal Installation
Vertical Installation
Figure D Figure E Figure F
Figure A Figure B Figure C
Prior to servicing any Watts valve, it is mandatory to shut down
the water system by closing both the inlet and outlet shutoff
valves. After shutoff valves are closed, open test cock #2, #3
and #4 to relieve pressure within the backflow assembly.
1. After #3 test cock has been opened to relieve pressure,
remove #3 test cock from housing. (Figure A)
2. Slowly slide the cover sleeve to the downstream side of the
housing. (Figure B)
3. Remove the stainless steel check retainer from the housing.
(Figure B)
4. Remove the #1 check module (Figure C) by inserting two
flat blade screwdrivers into the slots on either side of the
check module and gently pry to check module toward the
open zone.
5. Remove #2 check module with the same instructions as in
#4 above. For servicing 6" (150mm) checks see 8" – 10"
(200 – 250mm) instructions on p. 3.
6. To clean or inspect either check module, insert a #3 screw-
driver through the downstream side of the check module as
shown in Figure D and E. When the screwdriver is in place,
remove the E-clip (Figure F) and pin connecting the structur-
al members and the check clapper will open with no tension.
7. Thoroughly clean the seating area. The sealing disk may be
removed, if necessary, by removing the screws connecting
the keeper plate to the clapper. The sealing disc may be
reversed and reinstalled if the elastomer is cut or damaged.
8. Wash check module and O-ring and inspect for any dam-
age. If damaged, reinstall new parts.
9. After thorough cleaning, lubricate O-ring w/FDA approved
lubricant, replace pin and E-clip in structural members,
remove screw driver and reinstall check modules and
assemble housing in reverse order of these instructions.
Maintenance Instructions 21/2" – 6" (65 – 150mm)
Basic Installation Instructions

3
Test Procedures Double Check Valve Assemblies
Test Check Valve No.1
Step 1: Ensure shutoff #1 is open, shutoff #2 is closed.
Step 2: Connect high side hose to test cock #3, low side to test
cock #2 and open both test cock #2 and test cock #3.
Step 3: Open valve C, then open A to bleed air from the high
side. close valve a, then open B to bleed low side.
Close valve B.
Step 4: Connect vent hose loosely to test cock#1. Open valve
A to vent air from vent hose, Tighten vent hose at test
cock #1, open test cock #1.
Step 5: Close shutoff #1. Slowly loosen hose at test cock #2
until differential gauge rises to 2psi and retighten hose.
If the differential reading does not decrease, record
check valves as “tight”.
Test Check Valve No. 2
Step 1: Move the high side hose to test cock #4, low side to
test cock #3 and open both test cock #3 and test
cock #4. Remove vent hose from test cock #1, open
shutoff #1.
Step 2: Open valve C, then open valve A to bleed air from the
high side. Close valve A, then open valve B to bleed
low side. Close valve B.
Step 3: Connect vent hose loosely to test cock #1. Open valve
A to vent air from the vent hose, Tighten vent hose at
test cock #1, open test cock #1.
Step 4: Close shutoff #1, then slowly loosen hose at test cock
#3 until differential gauge rises to 2psi and retighten
hose. If the differential reading does not decrease,
record check as tight. Remove all hoses and restore
valve to original working condition.
Note: The assembly will fail both the first and second check
valve tests above, if shutoff #2 leaks excessively. To test for a
leaky #2 shutoff, use the following procedure.
Test for Leaky No. 2 shutoff
Step 1: Connect the high side to test cock #1, low side to test
cock #4. Open test cock #1 and test cock #4. Close
shutoffs #1 and #2.
Step 2: Close valve C. Open valve A, then open valve B 1⁄2
turn, loosen hose at test cock #4 to remove air.
Retighten hose.
Step 3: If the differential gauge rises above 0, there is exces-
sive leakage at shutoff #2 and it must be replaced to
test the assembly.
Ball Type Test Valves
AC
B
Needle
Valve
High Hose
(Yellow)
Low Hose
White or Red
Vent Hose
(Blue)
Test Cock Test Cock Test Cock Test Cock
No. 1 No. 2 No.3 No.4
Material/Tool Requirements:
•#3 Phillips screwdriver or 5/16" diameter rod, length sufficient to
span diameter of check, see Figures A and B.
•1/2– 13 x 5" fully threaded hex bolt (Service bolt).
•3/4" open end or socket wrench.
Instructions:
Prior to servicing any Watts valve, it is mandato-
ry to shut down the water system by
closing both the inlet and outlet
shutoff valves. After shutoff valves
are closed, open test cock #2, #3 & #4 to
relieve pressure within the backflow assembly.
1. After #3 test cock has been opened to relieve
pressure, remove #3 test cock from housing.
When repairing an 8" or 10" (200 – 250mm) device, remove
both Victaulic couplers from body. Slide the downstream
Victaulic coupler gasket to the downstream side of the hous-
ing. The upstream Victaulic coupler gasket stays in place.
2. Remove check/s to be maintenanced.
3. Locate the service hole and thread in the service bolt by hand
until it contacts the linkage. (Figure A)
4. Continue to thread in service bolt with the wrench until the
service hole in the linkage is aligned with the service notches
on the spring arbors. (Figure A)
5. Insert the Phillips screwdriver through the arbors and service
hole of the linkage making sure that the tip of the screwdriver
extends past the ends of the arbors by a minimum of 1/4"
(6mm). (Figure B)
6. Back out the service bolt until load is transferred to the screw-
driver. Continue to back out the service bolt until sufficient clear-
ance is achieved to remove the complete spring mechanism.
7.To disconnect linkage, remove retaining clip and pin (store in a
safe location for reinstallation).
8. To remove spring mechanism, grasp the screwdriver at the
center and pull complete assembly straight out and store in a
safe place.
9. Reinstall in reverse.
WARNING – While the spring mechanism is removed for check
servicing; never pull the screwdriver out or off the support notch-
es on the arbors. Doing so may cause bodily injuries.
Maintenance Instructions 8" – 10" (200 – 250mm)
Figure A
Figure B
Service Hole

757, 757DCDA Repair Kits
Closure Sleeve Test Cock
with O-ring
Closure Sleeve
E-clip
Disc Elastomer
Second Check Module
Sleeve O-ring and Gasket
Check Module O-ring
First Check Module
ORDERING NO. SIZE MODEL
1st Check Kits
7018128 2
1
⁄ 2 " - 4" RK 757/757DCDA CK1
7018131 6" RK 757/757DCDA CK1
7018134 8" RK 757/757DCDA CK1
0899200 10" RK 757/757DCDA CK1
Kit consists of: First check module, Check module O-ring and
Disc elastomer
2nd Check Kits
7018130 2
1
⁄ 2 " - 4" RK 757/757DCDA CK2
7018133 6" RK 757/757DCDA CK2
0899206 8" RK 757/757DCDA CK2
0899201 10" RK 757/757DCDA CK2
Kit consists of: Second check module, Check module O-ring and
Disc elastomer
ORDERING NO. SIZE MODEL
1st or 2nd Check Rubber Parts Kits
0899202 2
1
⁄ 2 " - 4" RK 757/757DCDA RC4
0899203 6" RK 757/757DCDA RC4
0899204 8" RK 757/757DCDA RC4
0899205 10" RK 757/757DCDA RC4
Kit consists of: Check module O-ring, Disc elastomer and E-clip
Check Sleeve Cover Kits
0899211 2
1
⁄ 2 " - 4" RK 757/757DCDA C
0899212 6" RK 757/757DCDA C
0899213 8" RK 757/757DCDA C
0899214 10" RK 757/757DCDA C
Kit consists of: Closure sleeve, Sleeve O-ring and Gasket
Watts USA Website: www.wattsreg.com • Watts Canada Website: www.wattscda.com
RP/IS-757/757DCDA 0314 EDP# 1915343 © Watts Regulator Co., 2002 Printed in U.S.A.