Watts 757 Series Setup guide

Series 757, 757DCDA, LF757DCDA
Series 757N, 757NDCDA, LF757NDCDA
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
installation requirements.
Note: For Australia and New Zealand: Pipeline strainers should
be installed between the upstream shutoff valve and the inlet of
the backflow preventer.
It's 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 system,
all mechanical checks, such as alarm checks and backflow
preventers, should be flow tested and inspected internally in
accordance with NFPA 13 and NFPA 25.
RP/IS-757/757DCDA
TM
Limited Warranty: Watts Regulator Co. (the “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.
THE WARRANTY SET FORTH HEREIN IS GIVEN EXPRESSLY AND IS THE ONLY WARRANTY
GIVEN BY THE COMPANY WITH RESPECT TO THE PRODUCT. THE COMPANY MAKES NO OTHER
WARRANTIES, EXPRESS OR IMPLIED. THE COMPANY HEREBY SPECIFICALLY DISCLAIMS
ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE.
The remedy described in the first paragraph of this warranty shall constitute the sole and exclu-
sive 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 repair-
ing or replacing other property which is damaged 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, improper installation or improper maintenance or alteration of the product.
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 appli-
cable state laws to determine your rights. SO FAR AS IS CONSISTENT WITH APPLICABLE
STATE LAW, ANY IMPLIED WARRANTIES THAT MAY NOT BE DISCLAIMED, INCLUDING
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE, ARE LIMITED IN DURATION TO ONE YEAR FROM THE DATE OF ORIGINAL
SHIPMENT.

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/LF 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.
Note: Assembly body should not be painted.
Horizontal Installation
N Pattern
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. Insert a #3 screwdriver through the hole on the top of the
cover sleeve and using both hands rotate the cover sleeve
approximately 1/4-turn clockwise and 1/4-turn counter-clock-
wise to break the sleeve O-ring seals. Using the screwdriver,
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 the 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
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 & #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

Series 757, 757N, 757DCDA, LF757DCDA
757NDCDA, LF757NDCDA Repair Kits
ORDERING NO. SIzE DISC MODEL
in. mm
1st Check Kits
7018128 21⁄2 - 4 65-100 Red Silicone RK 757/757DCDA CK1
7018131 6 150 Red Silicone RK 757/757DCDA CK1
7018134 8 200 Red Silicone RK 757/757DCDA CK1
0899200 10 250 Red Silicone RK 757/757DCDA CK1
Kit consists of: First check module, Check module O-ring and
Disc elastomer
2nd Check Kits
7018130 21⁄2 - 4 65-100 Red Silicone RK 757/757DCDA CK2
7018133 6 150 Red Silicone RK 757/757DCDA CK2
0899206 8 200 Red Silicone RK 757/757DCDA CK2
0899201 10 250 Red Silicone RK 757/757DCDA CK2
Kit consists of: Second check module, Check module O-ring and
Disc elastomer
ORDERING NO. SIzE DISC MODEL
in. mm
1st or 2nd Check Rubber Parts Kits
0899202 21⁄2 - 4 65-100 Red Silicone RK 757/757DCDA RC4
0899203 6 150 Red Silicone RK 757/757DCDA RC4
0899204 8 200 Red Silicone RK 757/757DCDA RC4
0899205 10 250 Red Silicone RK 757/757DCDA RC4
Kit consists of: Check module O-ring, Disc elastomer and E-clip
Check Sleeve Cover Kits
0899211 21⁄2 - 4 65-100 – RK 757/757DCDA C
0899212 6 150 – RK 757/757DCDA C
0899213 8 200 – RK 757/757DCDA C
0899214 10 250 – RK 757/757DCDA C
Kit consists of: Closure sleeve, Sleeve O-ring and Gasket
Sleeve O-ring and Gasket
Check Module O-ring
First Check Module
Closure Sleeve Test Cock
with O-ring
Closure Sleeve
E-clip
Disc Elastomer
Second Check Module
RP/IS-757/757DCDA 1018 EDP# 1915343 © 2010 Watts
USA: 815 Chestnut St., No. Andover, MA 01845-6098; www.watts.com
Canada: 5435 North Service Rd., Burlington, ONT. L7L 5H7; www.wattscanada.ca
A Watts Water Technologies Company