The Watts 957-NRS-S-FS 4 is a 4" reduced pressure zone (RPZ) backflow preventer with Flanged connections, approved for high health hazard protection. It features a stainless body and a rubber seat. Rated to 175 psi and 33°F to 140°F.
This 4" reduced pressure zone assembly backflow preventer help stop the reverse flow of liquids due to backpressure or backsiphonage, where potential health hazard exists. This extremely compact and lighter than a traditional designed assembly is approved for horizontal installation as long as backflow assembly is installed in accordance with the direction of the flow arrow. This assembly consists of a stainless steel body with quick access sleeve, cast iron flanged strainer, torsion spring check valves, resilient seated gate valves with non-rising stem, test cocks and corrosive resistant stainless steel bottom mounted pressure relief valve. This backflow assembly contains a flood sensor with SentryPlus Alert® technology to detect excessive water discharges from the relief valve. When paired with an add on connection kit, the sensor is activated to relay alerts for potential flooding events. Connection kit options include BMS, cellular communication, and the Sensor Control Monitor which enables integration with BAS via RS-485 Modbus or the Nexa® platform through Wi-Fi.
Features
- Features a flood sensor with SentryPlus Alert technology to detect continuous discharge from the relief valve
- Add-on sensor connection kit to extend flood monitoring on compatible assemblies
- Integrates with the Sensor Control Monitor to deliver maintenance alerts to BAS via RS-485 Modbus or the Nexa platform by Wi-Fi connectivity
- 304 (Schedule 40) stainless steel housing and sleeve
- UL and FM outside stem and yoke resilient seated gate valves
- Replaceable check disc rubber
- Bottom mounted cast stainless steel relief valve
- Compact design allows small enclosures to be used
- Groove couplings for ease of installation and pipe alignment
- Includes: Test Cocks
- Includes: Strainer
- Includes: Flood Sensor
Common Questions
- What hazard level is this RPZ approved for?
- It is rated for high health hazard (toxic) cross-connections, so it may be used on either high or low hazard service. The assembly is listed to ASSE 1013.
- 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 with 4 test cocks. 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 non-rising stem (NRS) resilient-seated gate valves on the inlet and outlet.
- Is this listed for fire protection service?
- Yes — it is UL Classified and FM Approved, the listings normally required for a backflow device on a fire sprinkler supply.
- How does this have to be installed?
- It is approved for horizontal installation only, with the flow arrow on the body pointing in the direction of flow.
- Does the relief valve need a drain?
- Yes. An RPZ relief valve is designed to discharge, and it can dump a large volume of water, so it must never be installed in a pit or below grade and the discharge must be piped to an adequate drain through an air gap. The air gap fitting is not included with this model and is ordered separately. This model includes the SentryPlus Alert flood sensor, which signals a relief-valve discharge before it becomes a flood.
Specifications
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Type: RPZ
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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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Body Material: Stainless
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Seat / Seal Material: Rubber
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Max Pressure (psi): 175
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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: 957-NRS-S-FS 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: No
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Assembly Type: RPZ
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Hazard Protection Level: High Health Hazard
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ASSE Standard: ASSE 1013
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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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Number of Test Cocks: 4
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Shutoff Valves: NRS Gate
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Approved Orientation: Horizontal
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Flood Sensor (SentryPlus Alert): Yes
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Strainer Included: Yes
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Air Gap Fitting Included: No
