Watts 757a Series Manuale utente

Series 757a/757aDCDA

Double Check Valve Assemblies

Double Check Detector Assemblies

Sizes: 21⁄2" – 6" (65 – 150mm)

• 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

and F-RK-DC.

For technical assistance, contact your local Watts representative.

Watts 757a 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-757a/757aDCDA

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.

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 757a and 757aDCDA 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.

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

Basic Installation Instructions

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 exces-

sively. To test for a leaky #2 shutoff, use the follow-

ing 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

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

757a/757aDCDA 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

0899250 2

⁄

" - 4" RK 757a/757aDCDA CK1

0899251 6" RK 757a/757aDCDA CK1

Kit consists of: First check module, Check module O-ring,

Disc elastomer

2nd Check Kits

0899254 2

⁄

" - 4" RK 757a/757aDCDA CK2

0899255 6" RK 757a/757aDCDA CK2

Kit consists of: Second check module, Check module O-ring,

Disc elastomer

ORDERING NO. SIZE MODEL

1st or 2nd Check Rubber Parts Kits

0899258 2

⁄

" - 4" RK 757a/757aDCDA RC4

0899259 6" RK 757a/757aDCDA RC4

Kit consists of: Check module O-ring, Disc elastomer and E-clip

1st or 2nd Check Cover Kits

0899266 2

⁄

" - 4" RK 757a/757aDCDA C

0899267 6" RK 757a/757aDCDA C

Kit consists of: Closure sleeve, 2 pieces of sleeve O-ring

Watts USA Website: www.wattsreg.com • Watts Canada Website: www.wattscda.com

RP/IS-757a/757aDCDA 0230 EDP# 1915344 © Watts Regulator Co., 2002 Printed in U.S.A.

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