Watts 774 User Manual
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
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