Series 774/774DCDA
774X/774XDCDA
Double Check Backflow Preventer
Double Check Detector Assemblies
Sizes: 21⁄2" - 12" (65 - 300mm) 774
4" - 12" (100 - 300mm) 774DCDA
6" - 8" (150 - 200mm) 774X/774X DCDA
• Installation
• Service
• Repair Kits
• Maintenance
For eld testing procedure, send for IS-TK-DP/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 on back page.
RP/IS-774/774DCDA/774X/774XDCDA
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.
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 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 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 applicable
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.
Installation Instructions
Watts Series 774 Double Check Valve
Installation Note:
The ange gasket bolts for the gate valves should
be retightened during installation as the bolts may
have loosened due to storage and shipping.
#3 Test Cock
#2 Test Cock
#4 Test Cock
Inlet
Shutoff
Valve
#1 Test Cock
First
Check
Check with local authorities for installation requirements.
Install valve in the line with arrow on valve body pointing in the
direction of flow. Pipe lines should be thoroughly flushed to remove foreign material
installed as shown, ahead of the backflow preventer to prevent discs
from unnecessary fouling.
before installing the unit. A strainer should be
CAUTION: Do not install a strainer when backflow preventer is
used on seldom-used water lines which are called upon during
emergencies, such as fire sprinkler lines, etc.
It is important that Series 774 be tested periodically in compliance
with local codes, but at least once a year or more often, depending upon system conditions.
Second Check
774 Series for Retrofit Installations
Vertical Flow Up
Vault Installation
Outlet
Shutoff
Valve
Watts 774
Watts 774
12” min.
Refer to
Local Codes
12” min.
Refer to
Local Codes
2
Installation Instructions
Watts Series 774
Installation
A. Series 774 may be installed in a horizontal or vertical flow up
position. The shutoff valve with the test cock is to be mounted on the inlet side of the backflow preventer. The test cock
is on the inlet side of the shutoff valve.
B. The 774 should always be installed in an accessible location
to facilitate testing and servicing. Check state and local
codes to insure that the backflow preventer is installed in
compliance, such as the proper height above the ground.
The backflow preventer must be supported and is not designed to carry full weight of the stand pipe.
C. Backflow preventers should never be placed in pits unless
absolutely necessary and then only when and as approved
by local codes. Consult your local or state plumbing or health
inspector. Watts recommends installation indoors or above
ground in an insulated enclosure.
Start Up
D. The downstream shutoff should be closed. Open upstream
slowly, fill the valve and bleed the air through Test cock 2,
3 and 4. When valve is filled, open the downstream shutoff
slowly and fill the water supply system. This is necessary to
avoid water hammer or shock damage.
E . Two or more valves can be piped in parallel (when approved)
to serve a large supply pipe main. This type of installation is
employed where increase capacity is needed beyond that
provided by a single valve and permits testing or servicing of
an individual valve without shutting down the complete line.
The number of assemblies used in parallel should be determined by the engineer’s judgement based on the operating
conditions of a specific installation.
12” min.
Refer to
Local Codes
Watts 774
12” min.
Refer to
Local Codes
Above Ground
Parallel
* For additional information on Watts insulated
enclosures send for ES-WB or ES-WBT.
*Insulated Enclosure
Watts 774
3
Servicing First and Second Checks
#1 Check 21⁄2"-6"
Spring
O-ring Seal &
Groove
Seat
O-ring Seal &
Groove
#2 Check
O-ring Seal &
Groove
Lug
Seat
O-ring Seal & Groove
Cam Arm
Hole
6" & 8" only
Roller
Clapper
Spring
Cam Arm
Roller
Hole
6" & 8" only
Clapper
Removing Check Assemblies –
Before servicing be certain shut off valves
are closed
1. Slowly open all ball valves to relieve air and water pressure.
Loosen bolts on groove coupler and remove groove coupler
and cover plate from valve body.
2. Remove #1 Check assembly by using your hands to
unscrew (turn counterclockwise) Check and remove through
top access port. Do not use Arm as a handle to unscrew.
If Check can not be loosened by hand, insert a long screwdriver between valve body and Check (see Figure 3). Slowly
apply pressure against the Check until loosened. Finish
unscrewing by hand. Unscrew #2 Check (turn counterclockwise) by placing a long screwdriver between lugs and applying pressure to loosen #2 Check. Finish unscrewing by hand.
3. To clean #1 Check, (6' and 8" only) locate the Check Arm
opening stud on the outlet flange of the valve assembly.
Slide the Check Arm over the stud with the check threads
facing downward (Figure 1). Tighten 1⁄4" nut on stud to secure
Check bar.
Threaded Stud on
Valve Outlet Flange
6" & 8" 1st Check DC
6" & 8" 2nd Check DC
Figure 1
Cleaning Position
Figure 2
Slowly pull the assembly outward to open check allowing exposure of the seat and clapper contact area for cleaning. To clean
#2 Check, lift Check Arm and hold in open position. Raise clapper so that the end of the Check Arm rests between roller and
clapper (Figure 2). Thoroughly clean the seat area and clapper
sealing surfaces of both Checks. Inspect seats, clapper sealing
surfaces, Check Arms, and O-rings for damage. If not damaged
gently close the clapper. If damaged, install a new Check assembly and/or O-ring.
4. Before reinstallation of Checks thoroughly clean O-ring
groove and lubricate O-ring w/FDA approved lubricant. Insert
and thread #2 Check first and then #1 Check. #2 Check
should be tightened by inserting a long screwdriver between
lugs to tighten firmly. Do not over tighten. Tighten #1 Check
firmly by hand only. Replace cover plate, clean groove
coupler gasket and groove, replace groove coupler.
Figure 3
4
Watts Series 774/744DCDA 21⁄2"- 6"
First Check
Second Check
774/774DCDA Repair Kits
EDP NO KIT NO. SIzE
First Check Kit
0888820 RK 774/774DCDA CK 1 21⁄2 - 4 65 - 100 21⁄2"-4" 774/774DCDA / 6" 774X/774XDCDA
0888821 RK 774/774DCDA CK 1 6 150 6" 774/774DCDA / 8" 774X/774XDCDA
Kits include: Complete #1 Check with Check O-ring.
Second Check Kit
0888822 RK 774/774DCDA CK 2 21⁄2 - 4 65 - 100 21⁄2"-4" 774/774DCDA / 6" 774X/774XDCDA
0888823 RK 774/774DCDA CK 2 6 150 6" 774/774DCDA / 8" 774X/774XDCDA
Kits include: Complete #2 Check with Check O-ring.
Cover Kit
0888824 RK 774/774DCDA C 21⁄2 - 4 65 - 100 21⁄2"-4" 774/774DCDA
0888825 RK 774/774DCDA C 6 150 6" 774/774DCDA / 8" 774X/774XDCDA
0888826 RK 774X/774XDCDA C 6 150 6" 774X/774XDCDA
Kit includes: Cover, Grooved Coupler & Gasket.
in. mm
5
Watts Series 774/744DCDA 8"- 12"
Check Studs
Check Studs
774/774DCDA Repair Kits
EDP NO KIT NO. SIzE
First or Second Check Kit
0888827 RK 774/774DCDA CK 4 8, 10, 12 200, 250, 300 774/774DCDA
Kits include: Complete Check with Check O-ring.
Cover Kit
0888828 RK 774/774DCDA C 8, 10, 12 200, 250, 300 774/774DCDA
Kits include: Cover, Grooved Coupler & Gasket.
in. mm
Servicing and Second Checks
#1 Cam-Check Figure 2
#2 Cam-Check Figure 3
Figure 4
Watts assemblies require minimum maintenance. All assemblies must be retested once maintenance has been performed.
(Before servicing be certain shut off valves are closed)
Removing Cam-Checks
1. Shut down water system and lock out system if possible.
Slowly open all ball valves to relieve air and water pressure.
Loosen bolts on groove coupler and remove groove couple
and cover plate from valve body
2. #1 Check (Fig.2) Using a 9⁄16" socket wrench or nut driver, re-
move the four nuts from the #1 check studs (See fig. 1) Using
two hands, place them at 12 o'clock and 6 o'clock, wiggle
the check assembly free. Remove through access port with
back of clapper first with back of clapper first with spring end
down. Pull check assembly out of main body.
#2 Check (Fig.3) After loosening bolts with a 9⁄16" socket,
remove bolts completely, Using the centerline access bar,
spin the cam assembly from the 9 o'clock position to the 12
o'clock position, then (without letting go of the access bar)
6
push the cam assembly slightly downstream so that the
clapper is now parallel to the valve body. Now bring the cam
assembly through the check retaining wall. Leave the cam
assembly clapper parallel to the valve body. Pull the cam
assembly through the access port.
3. Using a 3⁄8" nut driver or a piece of small diameter pipe, place
on the cam arm torsion spring and move away from and
around the torsion spring retaining bracket so as to relieve the
torsion spring tension. (See Figure 4) This will allow the cam
arm to move freely, enabling you to inspect the clapper face
and cam seat.Thoroughly clean the seat area and clapper
sealing surfaces, cam arms, and O-rings.
4. Before reinstallation of Checks thoroughly clean O-ring groove
and lubricate O-ring with F.D.A. approved lubricant.
Testing
Double Check Valve Assemblies
The following Test Procedure is one of several that is recognized
throughout the United States for verification of the functioning of
Backflow preventers.
The following procedure is not a specific recommendation.
The Watts series of test kits are capable of performing any
of the recognized Backflow test procedures.
A. Flush all test cocks.
B. Turn tester on (before connecting hoses). Tester must
read all zeroes. Close VA and VB.
Test No. 1 - Test No. 1 Check Valve
1.
Install high side hose between TC #2 and tester
connection A.
2.
Install low side hose between TC #3 and tester
connection B.
3. Open TC #2 then VA, bleed hose, then close VA.
4. Open TC #3 then VB, bleed hose, then close VB.
5. Install a bypass hose between VB and TC #1. Open TC #1
and bleed by loosening hose connection at VB. Tighten
hose connection, fully open VB.
Push - Print Head (wait) then Push - Star Test
6. Close shutoff valve #2 then #1.
7. Slowly open VA and loser high side pressure about -2 psi
below the low side pressure (differential reading about -2.0
psi). Close VA. If reading is maintained, record as “tight”.
If reading returns to 0 and the pressure A increases to
pressure B, the check is recorded as leaking. If the reading
returns to + psi, No. 2 shutoff valve is leaking excessively,
and must be replaced to test the valve.
8. Close all test cocks, remove hoses from TC #2 and TC #3
and TC #1. reopen shutoff valve #1. Proceed to Test No.2.
Push - Stop Test.
Test No. 2 - Test No. 2 Check Valve
1.
Install high side hose between TC #3 and tester
connection A.
2. Install low side hose between TC #4 and tester
connection B.
3. Open TC #3 then VA, bleed hose, then close VA.
4. Open TC #4 then VB, bleed hose, then close VB.
5. Install a bypass hose between VB and TC #1. Open TC #1
and bleed by loosening hose connection at VB. Tighten
hose connection, fully open VB.
Push - Start Test
6. Close shutoff valve #1.
7. Slowly open VA and lower high side pressure about -2 psi
below the low side pressure (differential reading about -2.0
psi). Close VA. If reading is maintained, record as “tight”.If
reading returns to 0 and the pressure A increases to pressure B, the check is recorded as leaking. If the reading returns to + psi, No. 2 shutoff valve is leaking excessively,
and must be replaced to test the valve.
Push - Stop Test.
Test 2
Watts TK-DP
VA
VB
VA
Test 1
Watts TK-DP
VB
Watts 774
Watts 774
It is important that this device be tested periodically in compliance
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, single checks and backflow preventers
should be inspected internally every one to five years in accordance
with NFPA 13 A and NFPA 25
For additional testing information send for IS-TK-DP/DL, IS-TK-9A
and IS-TK-99E
7
For additional information, visit our web site at: www.watts.com
A Watts Water Technologies Company
Canada: 5435 North Service Rd., Burlington, ONT. L7L 5H7; www.wattscanada.ca
USA: 815 Chestnut St., No. Andover, MA 01845-6098; www.watts.com
RP-IS-774/774DCDA/774X/774XDCDA 0829 EDP#1911292 © 2009 Watts
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