Watts LF909 Installation, maintenance & repair

RP/IS-909/909RPDA

Watts 909 OSY shown

Designed for inline servicing

IMPORTANT: Inquire with governing authorities for local installa-

tion requirements.

NOTICE

For Australia and New Zealand, line strainers should be installed 

between the upstream shutoff valve and the inlet of the backflow pre-

venter.

Its important that this device be tested periodically in compliance 

with local codes, but at least once per year or more as service con-

ditions 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.

Testing

For field testing procedure, send for IS-TK-DL, 

IS-TK-9A, IS-TK-99E and IS-TK-99D.

For repair kits and service parts, reference PL-RP-BPD at  

www.watts.com

For technical assistance, contact your local Watts 

representative.

Installation, Maintenance, & Repair 

Series 909, LF909, 909RPDA, LF909RPDA

Reduced Pressure Zone Assemblies 

Reduced Pressure Detector Assemblies

Sizes: 2

1

⁄

2

" – 10" (65 – 250mm)

Local building or plumbing codes may require modifications to 

the information provided.  You are required to consult the local 

building and plumbing codes prior to installation.  If this informa-

tion is not consistent with local building or plumbing codes, the 

local codes should be followed.

Need for Periodic Inspection/Maintenance:  This product 

must be tested periodically in compliance with local codes, but 

at least once per year or more as service conditions warrant.  

Corrosive water conditions, and/or unauthorized adjustments 

or repair could render the product ineffective for the service in-

tended.  Regular checking and cleaning of the product’s internal 

components helps assure maximum life and proper product 

function. 

WARNING

!

Read this Manual BEFORE using this equipment.

Failure to read and follow all safety and use information 

can result in death, serious personal injury, property 

damage, or damage to the equipment.

Keep this Manual for future reference.

Basic Installation Instructions

NOTICE

The flange gasket bolts for the gate valves should be re tight ened 

during in stal la tion as the bolts may have loos ened due to stor age 

and  ship ping.

High Capacity Relief Series: 

Location and Installation Considerations

  1.  Backflow preventers must be installed in high-visibility locations 

in order to allow for immediate notice of telltale discharge or 

other malfunction. This location should also facilitate testing and 

ser vic ing, and protect against freezing and vandalism.

  2.  Installing a backflow preventer in a pit or vault is not rec om-

mend ed. However, if this becomes necessary, Watts highly rec-

om mends that a licensed journeyman tradesperson, who is rec-

ognized by the authority having jurisdiction, be consulted to 

ensure that all local codes and required safety provisions are 

met. An air gap below the relief port must be maintained so as 

to avoid flooding and submersion of the assembly, which may 

lead to a cross connection. *Please refer to Figure No. 1 for fur-

ther information.

  3.  A strainer should be installed ahead of the backflow preventer to 

protect all internal components from unnecessary fouling.

CAUTION

!

Do not install a strainer ahead of the backflow preventer on seldom-

used, emergency water lines (i.e. fire sprinkler lines). The strainer 

mesh could potentially become clogged with debris present in the 

water and cause water blockage during an emer gen cy.

  4.  Normal discharge and nuisance spitting are accommodated by 

the use of a Watts air gap fitting and a fabricated indirect waste 

line. Floor drains of the same size MUST be provided in case of 

excessive discharge. *Please refer to Figure No. 1 and Figure 

No. 2 for further in for ma tion.

  5.  When a 909/LF909 Series backflow preventer is installed for 

dead-end service applications. (i.e. boiler feed lines, cooling 

tower makeup or other equip ment with periodic flow require-

ments), discharge from the relief vent may occur due to water 

supply pressure fluctuation during static no-flow con di tions. A 

check valve may be required ahead of the backflow preventer. 

*Please see “Troubleshooting”, Page 7, prior to installation.