The Watts 757N-DCDA-DOSY-LM 3 is a 3" double check detector assembly (DCDA), approved for low health hazard protection. It features a stainless body and a silicone seat. Rated to 175 psi and 33°F to 140°F.
This 3 inch N pattern double check detector backflow preventer assembly is designed to prevent the reverse flow of fire protection substances and water of non-potable quality, but not toxic, from being pumped or siphoned into the potable water supply due to backsiphonage and or backpressure in accordance with national plumbing codes and water authority requirements. It is ideal for protection at cross-connections identified as non-health hazards such as on fire protection systems and from other contaminants found at the service line entrance. This compact modular design with a single access cover for easy maintenance is approved for horizontal and vertical flow up installation. It consists of a light weight stainless steel body and sleeve, domestic outside stem and yoke resilient seated gate valves, captured spring check valves, a bypass less meter to detect underground leaks and unauthorized water use, and four test cocks.
Features
- Stainless steel housing and sleeve
- Domestic outside stem and yoke gate valves
- Non-health hazard application
- No special tools required for servicing
- Includes: Test Cocks
- Includes: Bypass
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.
- Can this be installed on potable water?
- No. This model is not certified lead-free, so it may not be installed in potable water systems in states enforcing the NSF/ANSI 372 weighted-average lead rule. Use it on non-potable service — fire lines, irrigation or industrial water — or order the LF (lead-free) version of this model for drinking-water use.
- 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.
- How does this have to be installed?
- This assembly is approved for horizontal N-pattern installation, with the shutoff valves in line with the body. USC approval is orientation-specific, so it must be installed in that position.
Specifications
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Type: Double Check
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Size: 3"
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Inlet Size: 3"
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Outlet Size: 3"
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Body Material: Stainless
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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: 757N-DCDA-DOSY-LM 3
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Temperature: 33°F to 140°F
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Certifications: UL, FM, USC
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Lead-Free: No
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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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Approved Orientation: N-Pattern
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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
