8" Deringer 40
Backflow Direct's 8" Deringer 40 Reduced Pressure RP RPZ Backflow Prevention Valve
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The 8" Deringer 40 Reduced Pressure Valve prevents non-health hazard pollutants and hazardous contaminants from entering a potable water supply system when backpressure and/or backsiphonage conditions occur.
    The smallest,
    most economical,
    best performing,
    and only all stainless steel
    backflow preventer. Period.

Important Note: Install with FLEX Couplings or Flange Adapters Only. DO NOT use RIDGED Couplings!

MSRP: $5,249.00
Pro Price: $4,199.00

Product Code: BFD-8040

Relief Valve ships attached to Backflow [Add $110.00]
**Select this option if your water authority requires the relief valve to be attached to the backflow assembly at the time of shipment. See the University of Southern California Foundation for Cross Connection Control and Hydraulic Research, Manual of Cross-Connection Control Tenth Edition Section General Statement of Policy Regarding Assembled Assemblies, which states the following: “…In order to ensure proper installations, all backflow assemblies shall be delivered for installation completely assembled by the original manufacturer with all components as approved…”

Specifications Technology Downloads

The Deringer 40 Reduced Pressure Valve prevents non-health hazard pollutants and hazardous contaminants from entering a potable water supply system when backpressure and/or backsiphonage conditions occur. Used primarily on fire sprinkler systems when monitoring of unauthorized water use is required.

Maximum Working Pressure:
175psi (12.1 bar)
Temperature Range:
33° - 140°F (1° - 60°C)
End Connections
- IPS Groove for Steel Pipe:
- Flange Adapters:
ANSI B16.1 Class 125
Lead Free:
0.25% Maximum by Weight

Flow Performance

Measures & Materials

Valve Housing:
304 Stainless Steel
Valve Cover:
304 Stainless Steel
SOV Disks:
SOV Shafts:
304 Stainless Steel
SOV Bearings:
Non Wetted Bolts:
Grade 8 Zinc Plated
Check Disks:
Wetted Fasteners:
18-8 Stainless Steel
Check Springs:
17-7 Stainless Steel
Check Pins:
17-7/18-8 Stainless Steel
Check Seats:
Noryl Polymer

Engineering & Specifications

The Deringer 40 Reduce Pressure (RP) valve shall utilize two independent check modules and two integral resiliently seated shut-off valves all of which shall be contained within a single rigid valve housing constructed entirely of 304 stainless steel. Both integral shutoff valves shall include pre-wired supervisory tamper switches contained within a weatherproof actuator housing approved for both indoor and outdoor use. Dual Action Check modules shall operate as a “poppet style” check under low flow conditions, operate as a “swing style” check under high flow conditions and utilize replaceable silicone elastomer sealing discs. Assembly test cocks shall be handle-less and operate via a tamper resistant actuator. Assembly shall have a single full access service port and cover with an “inline” replaceable elastomer seal. Relief Valve shall operate using only static seals (zero dynamic/sliding seals). All wetted surface Relief Valve components shall be constructed of stainless steel. Assembly shall be serviceable without special tools and approved for horizontal applications.

Average Rating: 5 of 5 Total Reviews: 1 Write a review »

  0 of 0 people found the following review helpful:
Great Product and Superior Customer Service January 29, 2018
Reviewer: Mark from Fort Washington, PA United States  
I recently purchased an 8" Deringer 40 RP from Backflow Direct. I have been installing, servicing and testing Backflow preventers for 15 years and I am very impressed with the design of the components inside the unit which makes it very service friendly. The customer service that I have received has been outstanding, from the ordering process through the installation. I had an issue with debris coming from my very old water supply line into my 1st check valve after the installation. I consulted their support staff which have been extremely helpful with a resolution to my issue. I would highly recommend this product for any 2" and larger piping systems. My only suggestion to the company would be to produce this design unit in smaller sizes, 1" through 1-1/2".

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