Zurn Wilkins 6-375A 6" RPZ Reduced Pressure Backflow Preventer with NRS Gate Valves

Zurn Wilkins 6-375A 6" Reduced Pressure Backflow Preventer with NRS Gate Valves

Product Overview

The Zurn Wilkins 6-375A 6" Reduced Pressure Principle Assembly is a lead-free commercial backflow preventer designed to protect potable water systems against both backsiphonage and backpressure of contaminated water. Supplied with full-port non-rising stem gate valves and flanged end connections, this heavy-duty RPZ assembly is engineered for high-hazard cross-connection protection in large commercial, industrial, institutional, municipal, and mechanical piping systems.

The Model 375A uses a low-headloss compound check design to support high flow capacity while maintaining dependable backflow protection. The check assemblies and relief valve are accessible from the top of the unit, allowing inspection and internal maintenance without removing the complete assembly from the pipeline.

Its epoxy-coated ductile iron body, 300 Series stainless steel internals, NORYL™ check components, EPDM seals, and stainless steel braided sensing line provide durable performance in demanding potable-water installations.

Key Features & Benefits

• Protects potable water systems against backsiphonage and backpressure
• Designed for high-hazard cross-connection applications
• Includes full-port non-rising stem gate valves
• ANSI Class 150 flanged inlet and outlet connections
• Low-headloss compound check design supports efficient water flow
• Top-access check assemblies and relief valve simplify maintenance
• Internal components can be serviced without removing the assembly from the line
• Epoxy-coated ductile iron body provides strength and corrosion resistance
• 300 Series stainless steel internal components, springs, and fasteners
• NORYL™ seat rings and check valve components
• EPDM seal rings for potable-water service
• Stainless steel braided relief-valve sensing line
• Lead-free construction for regulated potable-water installations
• Maximum working water pressure of 175 PSI
• Maximum working water temperature of 140°F
• Repair kits and connected monitoring accessories available separately

Why Choose the Zurn Wilkins 375A?

The Zurn Wilkins 375A combines high-flow commercial performance with a service-friendly design. Its top-access check assemblies and relief valve help reduce maintenance time by allowing inspection and repair without removing the complete assembly from the piping system.

The 6-375A is particularly well suited to large mechanical rooms, industrial facilities, institutional buildings, municipal systems, and other applications requiring substantial flow capacity and reduced pressure principle protection.

Commercial-grade ductile iron construction, stainless steel internals, and a corrosion-resistant epoxy finish make the 6-375A a durable choice for demanding potable-water installations.

Typical Applications

• Large commercial buildings
• Industrial facilities
• Hospitals and healthcare campuses
• Schools and universities
• Municipal and institutional facilities
• Manufacturing and processing plants
• Large multi-unit residential buildings
• Irrigation systems
• Boiler and HVAC make-up water systems
• Mechanical equipment connections
• Fire protection system connections where permitted
• Other high-hazard potable-water cross-connections

Final product selection and installation must comply with applicable plumbing codes, cross-connection-control requirements, and the authority having jurisdiction.

Engineering Specification

The Reduced Pressure Principle Backflow Prevention Assembly shall meet the requirements of NSF/ANSI/CAN 61 and shall be ASSE® Listed 1013. The assembly shall be supplied with full-port non-rising stem gate valves.

The main valve body and access covers shall be epoxy-coated ductile iron conforming to ASTM A536. The seat rings and check valve components shall be constructed from NORYL™. Internal components, fasteners, springs, and stems shall be manufactured from 300 Series stainless steel. Seal rings shall be EPDM, and O-rings shall be Buna-N.

The check assemblies and relief valve shall be accessible for inspection and maintenance without removing the device from the pipeline. The Reduced Pressure Principle Backflow Prevention Assembly shall be a Zurn Wilkins Model 6-375A.

Product Specifications

Dimensions & Weight

Dimensions and weights are approximate and do not include packaging.

Approximate Schedule 40 Pipe Capacity

Published values represent approximate Schedule 40 pipe capacity and should not be interpreted as the certified rated flow of the backflow assembly.

Materials of Construction

Standards & Approvals

• ASSE® Listed 1013
• AWWA C511 compliant with gate valves
• AWWA C550 compliant
• IAPMO® Listed
• CSA® Certified
• UL® Classified
• cUL® Classified
• FM® Approved
• Approved by the Foundation for Cross-Connection Control and Hydraulic Research at the University of Southern California
• NYC MEA 484-04-M
• Meets the requirements of NSF/ANSI/CAN 61
• Lead-free construction with no more than 0.25% weighted-average lead content

Approvals may vary by assembly size, valve configuration, installation orientation, and jurisdiction. Verify project-specific requirements before ordering.

Installation Tips

• Install the assembly in the direction of flow indicated on the valve body.
• Follow all applicable plumbing, backflow-prevention, and cross-connection-control regulations.
• Unless otherwise specified, mount the assembly at least 12" (305 mm) and no more than 30" (762 mm) above an adequately sized drain.
• Provide sufficient side and top clearance for testing, inspection, and internal maintenance.
• Position the relief valve above a drain capable of handling discharge during normal operation or a backflow event.
• Do not install the assembly where any portion of the unit may become submerged.
• Provide freeze protection and a suitable enclosure for outdoor installations in cold climates.
• Support adjoining piping independently to prevent excessive pipe weight or mechanical stress from being transferred to the assembly.
• Flush supply piping before installation to help prevent construction debris from damaging the checks or relief valve.
• Install an approved air gap where required for relief-valve drainage.
• Allow unrestricted access to the shut-off valves, test cocks, access covers, and sensing line.
• Have the completed installation tested by a qualified or certified backflow tester as required by the local authority.

Compatible Accessories

• Zurn AG air gap
• QT-SET Quick Test Fitting Set
• Rubber repair kit
• Zurn XT thermal expansion tank
• ZCSM-PF Connected Pressure Monitor
• ZCSM-BTM Connected Flow Meter
• Additional testing, service, and monitoring components specified for the Model 375A series

Accessories are sold separately unless expressly included in the product listing.

Frequently Asked Questions

What does the Zurn Wilkins 6-375A protect against?
The 6-375A protects potable-water systems against both backsiphonage and backpressure where a potential health hazard exists.

What shut-off valves are included?
The standard 6-375A includes full-port non-rising stem gate valves with flanged external pipe connections.

Is the Zurn Wilkins 6-375A lead-free?
Yes. The assembly is intended for regulated potable-water applications and meets the applicable requirement of no more than 0.25% weighted-average lead content.

Can the 375A be serviced without removing it from the pipeline?
Yes. The check assemblies and relief valve are accessible through the top access covers, allowing routine inspection and internal service without removing the complete valve body from the pipeline.

What is the maximum working pressure?
The maximum working water pressure is 175 PSI, or approximately 12.1 bar.

What is the maximum working temperature?
The maximum working water temperature is 140°F, or 60°C.

How much does the 6-375A weigh?
The standard configuration with flanged non-rising stem gate valves weighs approximately 356 lb, or 162 kg.

What flow capacity can the 6-inch piping support?
Published Schedule 40 pipe-capacity values range from approximately 450 GPM at 5 ft/sec to 1,351 GPM at 15 ft/sec. These figures describe approximate pipe capacity rather than the assembly's certified rated flow.

Does the assembly require drainage beneath the relief valve?
Yes. The reduced pressure relief valve can discharge during normal operation or during a backflow condition, so adequately sized drainage is required.

Does the assembly require periodic testing?
Yes. Reduced pressure principle assemblies generally require commissioning and recurring field testing by a qualified backflow tester. Testing frequency is determined by local regulations and the authority having jurisdiction.