Watts 775 Series Installation and user guide

Series
775/775DCDA
Double Check Backflow Preventer
Double Check Detector Assemblies
Sizes: 3" - 8"
• Installation • Service
• Repair Kits • Maintenance
LIMITED WARRANTY: Watts Regulator Company warrants each prod-
uctagainstdefectsinmaterialandworkmanshipforaperiodofoneyear
from the date of original shipment. In the event of such defects within
thewarrantyperiod,theCompanywill,atitsoption,replaceorrecondi-
tion the product without charge. This shall constitute the exclusive
remedy for breach of warranty, and the Company shall not be respon-
sible for any incidental or consequential damages, including without
limitation,damagesorothercostsresultingfromlaborcharges,delays,
vandalism,negligence,foulingcausedbyforeignmaterial,damagefrom
adverse water conditions, chemicals, or any other circumstances over
whichtheCompanyhasnocontrol.Thiswarrantyshallbeinvalidatedby
any abuse, misuse, misapplication or improper installation of the
product. THE COMPANY MAKES NO OTHER WARRANTIES EXPRESS
OR IMPLIED EXCEPT AS PROVIDED IN THIS LIMITED WARRANTY.
For field 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.
N775/N775DCDA Backflow Preventers are
identical in construction to 775/775DCDA Series
except include short radius elbows between
backflow preventer flange and gate valve flange.
RP/IS-775/775DCDA
IMPORTANT: Inquire with governing authorities
for local installation requirements.
NOTE: For Australia and New Zealand: Pipeline
strainers should be installed between the up-
stream shutoff valve and the inlet of the
backflow preventer.
CALIFORNIA PROPOSITION 65 WARNING
WARNING: This product contains chemicals
known to the State of California to cause cancer
and birth defects or other reproductive harm.
(Installer: California law requires that this
warning be given to the consumer.)
Insert lid bolts in holes
provided to remove 1st check

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Basic Installation Instructions
Installation Note:
The flange gasket bolts for the
gate valves should be retight-
ened during installation as the
bolts may have loosened due to
storage and shipping.
Check with local authorities for installation requirements. If
installing on a fire protection system be sure to purge air
from the system. Fill system slowly with all inspector test
valves open.
Pipe lines should be thoroughly flushed to remove foreign
material before installing the unit. A strainer should be in-
stalled as shown, ahead of the backflow preventer to prevent
discs from unnecessary fouling.
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 775 be tested periodically in compli-
ance with local codes, but at least once a year or more often,
depending upon system conditions.
775 Series for Retrofit Installations
Watts 775
12” min.
Refer to
Local Codes
Vault Installation
Vertical Flow
Up
12” min.
Refer to
Local Codes
Watts 775
Watts Series 775 Double Check Valve
#2 Test Cock
#3 Test Cock
#4 Test Cock
Outlet
Shutoff
Valve
Second Check
First
Check
#1 Test Cock
Inlet
Shutoff
Valve

3
Watts Series 775 Installation Instructions
Installation
A. Series 775 may be installed in a
horizontal or vertical flow up posi-
tion. 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 775 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 back-
flow 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. Con-
sult your local or state plumbing or
health inspector. Watts recom-
mends 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 sys-
tem. This is necessary to avoid wa-
ter 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 in-
crease capacity is needed beyond
that provided by a single valve and
permits testing or servicing of an in-
dividual 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 in-
stallation.
Above Ground
*Insulated Enclosure
Indoor Installation
Watts 775
Watts 775
*For additional information on Watts insulated enclosures send for ES-WB or ES-WBT.
12” min.
Refer to
Local Codes
12” min.
Refer to
Local Codes
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Removing Checks
Before Servicing Be Certain Shutoff Valves Are Closed
The assembly may be locked open by aligning the holes
in the cam bar and hinge arms and inserting a rod (see
Fig. 8, pg.6). If the clapper needs to be replaced or re-
paired, please refer to check disassembly instructions
and figures 6 through 10 on page 6. Caution: If the seat
is damaged, replace complete check module. If replace-
ment is not required, please continue.
To clean No. 2 check, lift arm and hold in open position
(see Fig. 9, pg. 6). Thoroughly clean the seat area and
clapper sealing surfaces of both checks. Rinse checks
and o-rings thoroughly.
Installation of Cam-Checks
Before installing checks, thoroughly clean o-ring grooves
and lubricate o-rings with FDA approved lubricant. Insert
and thread No. 2 check first and then No. 1 check. No. 2
check should be tightened by inserting a long screwdriver
between lid bolts inserted in seat ring to tighten. Prior to
filling the system, please ensure that lid bolts are tightened
(50 ft.lbs.), cover plate is properly secured, and test cocks
are open.
Start Up: The downstream shutoff should be closed. Open
upstream slowly, fill the valve and bleed the air through test
cocks 2, 3 and 4. When valve is filled, open the down-
stream shutoff slowly. This is necessary to avoid water
hammer or shock damage to the water system.
Figure 2
No. 2 Cam Check
(6" and 8" models only)
Place yourself so that the water flow through the valve is
left to right.
1. Shut down water system and lock out system if possible.
Slowly open all ball valves to relieve air and water pressure.
After pressure is relieved, loosen bolts on groove coupler
and remove groove coupler and cover plate from valve body.
2. Remove No. 1 check assembly by unscrewing (turn counter-
clockwise) check and remove through top access port. Do
not use arm as a handle to unscrew check. Insert lid bolts in
1st check seat ring (see Fig. 1), insert a long screwdriver or
pry bar between lid bolts. Gently apply pressure against the
bolts and turn seat assembly counter clockwise moving
bolts hole to hole to maintain turning leverage (two addi-
tional bolts will eliminate need to move lid bolts from hole to
hole). Finish unscrewing by hand and remove from valve
body. Unscrew No. 2 check (turn counterclockwise) by plac-
ing a long screwdriver across lid bolts inserted in holes lo-
cated in the 2nd check seat ring, similar in method used to
remove 1st check and applying pressure to loosen No. 2
check. Finish unscrewing by hand.
3.To clean check assemblies, locate the check arm opening
stud on the outlet flange of the valve assembly, (6" and 8"
only). Slide the arm over the stud with the check threads fac-
ing downward (Fig. 2). Tighten a 1⁄4" nut on stud to secure.
Slowly pull the assembly outward to open check allowing
exposure of the seat and clapper contact area for cleaning.
4
Figure 1
No. 1 Cam Check
Figure 6
Valve outlet flange
Threaded stud on flange

775/775DCDA Repair Kits
First Check Kit
EDP No. Kit No. Size For use with /Model #'s
0888900 RK 775/775DCDA CK 1 3" - 4" 3" - 4" 775/775DCDA/N775/N775DCDA
0888901 RK 775/775DCDA CK 1 6" - 8" 6" - 8" 775/775DCDA/N775/N775DCDA
Kits include: Complete No. 1 Check Assembly with Check O-ring.
Second Check Kit
0888902 RK 775/775DCDA CK 2 3" - 4” 3" - 4" 775/775DCDA/N775/N775DCDA
0888903 RK 775/775DCDA CK 2 6" - 8" 6" - 8" 775/775DCDA/N775/N775DCDA
Kits include: Complete No. 2 Check Assembly with Check O-ring.
Cover Kit
0888904 RK 775/775DCDA C 3" - 4” 3" - 4" 775/775DCDA/N775/N775DCDA
0888905 RK 775/775DCDA C 6" - 8" 6" - 8" 775/775DCDA/N775/N775DCDA
Kit includes: Cover, Grooved Coupler & Gasket.
First Check Rubber Parts Kit
0888906 RK 775/775DCDA RC1 3" - 4" 3" - 4" 775/775DCDA/N775/N775DCDA
0888907 RK 775/775DCDA RC1 6" - 8" 6" - 8" 775/775DCDA/N775/N775DCDA
Kit includes: First Check Assembly O-ring and Check Disc
Second Check Rubber Parts Kit
0888908 RK 775/775DCDA RC2 3" - 4" 3" - 4" 775/775DCDA/N775/N775DCDA
0888909 RK 775/775DCDA RC2 6" - 8" 6" - 8" 775/775DCDA/N775/N775DCDA
Kit includes: Second Check Assembly O-ring and Check Disc
Rubber Total Parts Kit
0888910 RK 775/775DCDA RT 3" - 4" 3" - 4" 775/775DCDA/N775/N775DCDA
0888911 RK 775/775DCDA RT 6" - 8" 6" - 8" 775/775DCDA/N775/N775DCDA
Kit includes: First and Second Check Assembly O-ring, and First and Second Check Disc
Watts Series 775/775DCDA 3" - 8"
Figure 3
Figure 4
Figure 5
No. 1 Cam-Check
Assembly
No. 2 Cam-Check
Assembly
1st Cam-check
O-ring (removable)
2nd Cam-check
O-ring (removable)
Groove Coupler
Groove Coupler
Gasket
Ball Valve
Ball Valve
Cover Plate
5
No. 1 Check Assembly
No. 2 Check Assembly

Check Parts and Disassembly
Before reinstallation of check assembly, thoroughly clean o-ring groove and lubricate o-ring with FDA approved lubricant.
Item No. Part Description
1. First Check O-ring (removable)
2. Clapper Assembly (removable)
3. Clapper Retaining Plate Screws (removable)
4. Clapper Retainer Plate (removable)
5. Clapper Disc (removable)
6. Pivot Arm Pin (removable ) Two c-clips
7. Second Check O-ring (removable)
Note: Align holes and
insert pin or small
screwdriver to hold in
open position.
Figure 7
Figure 8
Figure 9
Figure 10
Check Disassembly
Please use caution when disassembling check.
Check Parts
6
Figure 7
Using a thin rod or screwdriver, lift the bar
up so that the clapper is free to swing up-
wards away from the seat.
Figure 8
Using your free hand, swing the clapper
open until the roller is almost to the free
end of the bar. Align the maintenance
lockout holes in the bar and the hinge
arms. Secure the check assembly in the
maintenance position by inserting a rod or
thin screwdriver through the lockout holes.
Figure 9
Remove one c-clip from the center pivot
pin. Withdraw the center pivot pin from the
clapper and the hinge arms. Remove the
clapper assembly from the check assembly
module. Remove the retainer screws. Note:
You may replace this item as an assembly or
you may continue and replace only the disc.
Figure 10
Disassemble the clapper by removing four
screws, disc retainer and the sealing disc.
Disc may be flipped if sealing surface
is damaged.

7
For additional testing information send for IS-TK-DP/DL, IS-TK-9A and IS-TK-99E
Testing - Double Check Valve Assemblies
The following Test Procedure is one of several that is recognized throughout the United States for verifica-
tion of the functioning of Backflow preventers.
The following procedure is not a specific recommendation. The Watts series of test kits are capable of per-
forming 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 PSID
below the low side pressure (differential reading about -2.0
PSID). Close VA. If reading is maintained, record as “tight”.
If reading returns to 0 and the pressure A increases to pres-
sure B, the check is recorded as leaking. If the reading re-
turns to + PSID, 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 PSID
below the low side pressure (differential reading about -2.0
PSID). Close VA. If reading is maintained, record as “tight”.
If reading returns to 0 and the pressure A increases to pres-
sure B, the check is recorded as leaking. If the reading re-
turns to + PSID, No. 2 shutoff valve is leaking excessively,
and must be replaced to test the valve.
Push - Stop Test.
Watts 775 Watts 775
Watts TK-DP Watts TK-DP
Test 1 Test 2
VA
AB
VB VA VB
AB
It is important that this device be tested periodically in compli-
ance with local codes, but at least once per year or more as ser-
vice 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