The Watts LF757DCDA-OSY-LM 4 is a 4" lead-free double check detector assembly (DCDA) with Flanged connections, approved for low health hazard protection. It features a silicone seat. Rated to 175 psi and 33°F to 140°F. This model is certified lead-free for potable-water installations.
This 4" lead free double check detector backflow preventer assembly prevents the backflow of pollutants that are objectionable but not toxic, from entering into the potable water supply. It is designed for non-health hazard applications and may be installed under continuous pressure service to protect against both backpressure and backsiphonage. It is used primarily on fire sprinkler lines when it is necessary to monitor unauthorized use of water. This assembly consists of two independently operating tri-link check valves, two shutoff valves, four test cocks, and UL/FM outside stem and yoke resilient seated domestic gate valves. It features a compact stainless steel housing and sleeve that is 70 percent lighter than traditional designs. The maximum working pressure is 175 psi (12.06 bar).
Features
- Stainless steel for corrosion resistance
- Lightweight construction
- 150 pound ANSI/AWWA CL D flanged
- Outside stem and yoke shutoffs
- Includes: Test Cocks
Common Questions
- What hazard level is this DCDA approved for?
- It is rated for low health hazard (non-toxic, "pollutant") cross-connections only. Where the substance downstream could be a health hazard, codes require a reduced pressure zone (RPZ) assembly instead. The assembly is listed to ASSE 1048.
- Is this model legal for potable water?
- Yes. It is certified lead-free to NSF/ANSI 372, which is what state plumbing codes require for any device in a drinking-water line.
- Does this assembly have to be tested every year?
- Yes. This is a field-testable assembly. Most water authorities require it to be tested and certified by a licensed backflow tester at installation and annually thereafter. It carries USC FCCCHR approval, which many jurisdictions accept as their sole approval list.
- What shutoff valves are included?
- It is supplied with outside screw and yoke (OS&Y) gate valves on the inlet and outlet. OS&Y gates give the visible open/shut indication that fire-line and many water-authority specs require.
- Is this suitable for a fire sprinkler line?
- Yes. Detector assemblies are built for fire sprinkler service: the metered bypass registers the low flows that reveal a leak or an unauthorized tap on the fire line. This model is UL Classified and FM Approved. This is the "less meter" (LM) variant — the bypass line is supplied without the meter, which you specify separately.
Specifications
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Type: Double Check
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Size: 4"
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Inlet Size: 4"
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Outlet Size: 4"
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Connection: Flanged
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Seat / Seal Material: Silicone
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Max Pressure (psi): 175
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Application: Fire Protection
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Backflow Protection: Both
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Operation: Continuous
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Country of Origin: United States
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Warranty: 1 Year Limited
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MPN: LF757DCDA-OSY-LM 4
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Temperature: 33°F to 140°F
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Certifications: UL, FM, USC
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Lead-Free: Yes
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Assembly Type: DCDA
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Hazard Protection Level: Low Health Hazard
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ASSE Standard: ASSE 1048
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USC FCCCHR Approved: Yes
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Fire Protection Listing: UL Classified;FM Approved
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Field Testable: Yes
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Shutoff Valves: OSY Gate
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Flood Sensor (SentryPlus Alert): No
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Strainer Included: No
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Air Gap Fitting Included: No
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Bypass Meter: None
