Description
Zurn Wilkins 34-975XL 3/4" RPZ Reduced Pressure Backflow Preventer
Product Overview
The Zurn Wilkins 34-975XL 3/4" RPZ Reduced Pressure Principle Assembly is a bronze backflow preventer designed to protect potable water supplies against both backsiphonage and backpressure from contaminated water. Supplied with full-port QT ball valves and female NPT threaded connections, it provides high-hazard cross-connection protection for irrigation, mechanical equipment, industrial water systems, and other approved non-potable applications.
The Model 975XL features a compact wye-pattern bronze body that provides direct access to the first and second check assemblies without requiring removal of the relief valve or the complete device from the pipeline. This service-friendly design helps reduce maintenance time, labor requirements, and system downtime.
Cast-bronze construction, stainless steel fasteners and springs, Noryl™ internal polymers, and silicone and Buna-N elastomers provide durable performance in demanding residential, commercial, and industrial installations.
Key Features & Benefits
- Protects against both backsiphonage and backpressure
- Designed for high-hazard cross-connection protection
- Supplied with full-port QT ball valves
- 3/4" female NPT threaded inlet and outlet connections
- Compact wye-pattern bronze body reduces installation space
- First and second check assemblies are accessible in-line
- Checks can be serviced without removing the relief valve
- Complete assembly can remain installed during routine internal maintenance
- Cast-bronze main valve body and access covers
- 300 Series stainless steel fasteners and springs
- Noryl™ internal polymer components
- Silicone and Buna-N elastomers
- Maximum working pressure of 175 PSI
- Maximum working water temperature of 180°F
- Hydrostatic test pressure of 350 PSI
- ASSE® 1013 listed reduced pressure assembly
- Compatible air gap, strainer, repair kits, and testing accessories available separately
Why Choose the Zurn Wilkins 975XL?
The Zurn Wilkins 975XL combines compact bronze construction with convenient in-line service access. Its wye-pattern configuration allows technicians to reach the first and second check assemblies without removing the relief valve or taking the complete backflow preventer out of the piping system.
The 34-975XL is well suited to 3/4" water connections where reduced pressure principle protection is required. Its full-port ball valves, threaded connections, high-temperature capability, and established approval profile make it a dependable option for irrigation, equipment connections, and other approved non-potable applications.
The compact layout also makes the 34-975XL practical for mechanical rooms, utility spaces, and installations where available service clearance is limited.
Typical Applications
- Irrigation and sprinkler systems
- Boiler and HVAC make-up water connections
- Mechanical equipment connections
- Commercial water systems
- Industrial process-water connections
- Laboratory and institutional equipment
- Water treatment equipment
- Other high-hazard non-potable applications
The Model 975XL protects the potable water supply from a connected hazard, but Zurn specifies the assembly for non-potable applications only. Final product selection and installation must comply with local plumbing codes, cross-connection-control requirements, and the authority having jurisdiction.
Engineering Specification
The Reduced Pressure Principle Backflow Preventer shall be ASSE® Listed 1013, rated to 180°F, and supplied with full-port ball valves.
The main valve body and access covers shall be cast bronze conforming to ASTM B584. The seat rings and internal polymer components shall be Noryl™, and the seat-disc elastomers shall be silicone. Fasteners and springs shall be manufactured from 300 Series stainless steel.
The first and second check assemblies shall be accessible for maintenance without removing the relief valve or the complete assembly from the pipeline. Where installed indoors, the installation shall include an air-gap adapter. The assembly shall be intended for non-potable applications and shall be a Zurn Wilkins Model 34-975XL.
Product Specifications
| Specification | Details |
|---|---|
| Manufacturer | Zurn Wilkins |
| Model | 34-975XL |
| Series | 975XL |
| Assembly Type | Reduced Pressure Principle Assembly |
| Common Abbreviation | RP / RPZ |
| Nominal Size | 3/4" / DN20 |
| Shut-Off Valves | Full-Port QT Ball Valves |
| End Connections | Female NPT Threaded |
| Thread Standard | ANSI B1.20.1 |
| Maximum Working Pressure | 175 PSI / 12.1 bar |
| Maximum Working Temperature | 180°F / 82°C |
| Hydrostatic Test Pressure | 350 PSI / 24.1 bar |
| Main Body Material | Cast Bronze, ASTM B584 |
| Access Cover Material | Cast Bronze, ASTM B584 |
| Fasteners | 300 Series Stainless Steel |
| Springs | 300 Series Stainless Steel |
| Elastomers | Silicone and Buna-N |
| Internal Polymers | Noryl™ |
| Relief-Valve Discharge-Port Area | 0.63 sq. in. / 406 mm² |
| Application Classification | Non-Potable Applications Only |
| Order Number | 34-975XL |
Dimensions & Weight
| Dimension | Imperial | Metric |
|---|---|---|
| Overall Length with Ball Valves – A | 12" | 305 mm |
| Body Length – B | 7-3/4" | 197 mm |
| Dimension C | 2-1/8" | 54 mm |
| Dimension D | 3" | 76 mm |
| Dimension E | 3-1/2" | 89 mm |
| Dimension F | 5" | 127 mm |
| Dimension G | 16-1/8" | 410 mm |
| Approximate Weight | 12 lb | 5.5 kg |
| Order Number | 34-975XL | |
Dimensions and weights are approximate and do not include packaging.
Approximate Schedule 40 Pipe Capacity
| Pipe Velocity | Approximate Flow Capacity |
|---|---|
| 5 ft/sec | 8 GPM |
| 7.5 ft/sec | 12 GPM |
| 10 ft/sec | 17 GPM |
| 15 ft/sec | 25 GPM |
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
| Component | Material |
|---|---|
| Main Valve Body | Cast Bronze, ASTM B584 |
| Access Covers | Cast Bronze, ASTM B584 |
| Fasteners | 300 Series Stainless Steel |
| Springs | 300 Series Stainless Steel |
| Elastomers | Silicone and Buna-N |
| Internal Polymers | Noryl™ |
Standards & Approvals
- ASSE® Listed 1013
- cUPC® Listed
- UL® Classified when supplied less shut-off valves or with qualifying OS&Y valves
- cUL® Classified
- CSA® Certified B64.4
- AWWA C511 compliant
- Approved by the Foundation for Cross-Connection Control and Hydraulic Research at the University of Southern California
- NYC MEA 425-89-M Volume 3
Approvals may vary by exact 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 and cross-connection-control requirements.
- Install according to the manufacturer's instructions and the current applicable plumbing code.
- Unless otherwise specified, position the assembly at least 12" (305 mm) and no more than 30" (762 mm) above an adequately sized drain.
- Provide sufficient side clearance for testing, inspection, and maintenance.
- Do not install the assembly where any portion of the unit may become submerged.
- Use an air-gap adapter for indoor installations.
- Provide freeze protection and a suitable enclosure for outdoor installations in cold climates.
- Flush the piping before installation to help prevent debris from entering the check assemblies.
- Keep the ball valves, test cocks, access covers, and relief valve accessible.
- Provide drainage capable of accepting relief-valve discharge.
- Have the completed installation tested by a qualified or certified backflow tester as required by the authority having jurisdiction.
Compatible Accessories
- Zurn Model AG air gap
- Zurn Model SXL bronze Y-strainer
- Zurn repair kits
- Zurn Model XT thermal expansion tank
- Zurn Model 40XL2 soft-seated check valve
- Zurn Model 1260XL shock arrester
- QT-SET Quick Test Fitting Set
Accessories are sold separately unless expressly included in the product listing.
Frequently Asked Questions
What does the Zurn Wilkins 34-975XL protect against?
The 34-975XL protects the potable water supply from contamination caused by both backsiphonage and backpressure.
Is the 34-975XL intended for potable applications?
The assembly protects a potable water supply, but Zurn specifies the Model 975XL for non-potable applications only.
What shut-off valves are included?
The standard 34-975XL configuration includes full-port QT ball valves.
What type of pipe connections does it use?
The 34-975XL uses 3/4" female NPT threaded connections conforming to ANSI B1.20.1.
Can the check assemblies be serviced in-line?
Yes. The first and second checks can be accessed without removing the relief valve or the complete assembly 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 180°F, or approximately 82°C.
Is an air gap required?
Zurn specifies an air-gap adapter for indoor installations. Local drainage and plumbing requirements must also be followed.
How high should the assembly be installed above a drain?
Unless local requirements state otherwise, the assembly should be installed at least 12" and no more than 30" above an adequately sized drain.
Does the 34-975XL require periodic testing?
Testing requirements are determined by the local authority, but reduced pressure assemblies commonly require commissioning and recurring testing by a qualified backflow tester.
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