2 1/2" Deringer 50
2 1/2" Deringer 50
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The 2 ½" Deringer 50 Reduced Pressure Detector Assembly 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.
    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: $1,749.00
Pro Price: $1,399.00

Product Code: BFD-2550

Choose Your Bypass Options:

Relief Valve ships attached to Backflow [Add $80.00]
**Select this option if your water authority requires the relief valve to be attached to the backflow 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; “…In order to ensure proper installations, all backflow assemblies shall be delivered for installation completely assembled by the original manufacturer…”

Specifications Technology Downloads

The Deringer 50 Reduced Pressure Detector Assemby prevents non-health hazard pollutants 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

Micro type-II Bypass TM Assembly

The type-II bypass assembly is a new technology to the backflow industry and is used on Backflow Direct's Deringer 50 (RPDA-II).

As more manufacturers begin to utilize this technology it is only a matter of time before it’s widely used and is more commonly seen than the old type-I bypass assembly.

We created this video to provide a clear explanation on how the type-II bypass provides the EXACT same level of protection as a type-I bypass as well as some of the similarities and differences between the two.

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 50 Reduce Pressure Detector Assembly (RPDA-II) valve shall utilize two independent check modules and two integral resiliently seatedshut-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. All bypass assembly components shall be lead free and include a meter registering either gallons or cubic feet, a single check valve and required test cocks. The 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.

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