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2" (Deringer 50) Kit

The 2" (Deringer 50) Kit is a reduce pressure detector assembly that prevents non-health hazard pollutants from entering a potable water supply system when backpressure and/or backsiphonage conditions occur.

2" (Deringer 50) Kit Includes:

  • (1) 2½" Deringer 50
  • (2) 2½" Groove Couplings
  • (2) 2" NPT x 2½" Groove Adapter
End connections are union type stainless steel 2" female NPT threads for ease of installation. Entire valve housing is constructed of stainless steel (including shut off valves) for industry leading corrosion resistance.




Pro Price:


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.



True-Seal™  1st Check Modules

The True Seal Check Valve was designed to incorporate a poppet only motion during the check stroke and is used exclusively on the first check assembly on the Deringer RP and RPDA models. This design allows a more consistent pressure loss across the check valve which helps maintain a steady and continual closure of the Relief Valve.

  • Light weight engineered polymer components
  • Modular for easy removal of complete check from body
  • Easily disconnect spring tension for safe check servicing
  • Replaceable Silicone Rubber Elastomer Disk
  • Excellent resistance to fouling.
Skewed View
Low Flow Poppet Action

Poppet Action


  • 100% of check stroke is that of a poopet check
  • Consistent static sealing
  • Excellent resistant to fouling
  • Reliable check closure
  • Stable flow characteristics at ALL flow rates

Dual-Action™  2nd Check Modules

The Patented Dual-Action Check™ ( US8875733) is the core technology behind the superior performance of Deringer Backflow Prevention Product Line. The Dual-Action Check™ combines all of the best features of industry standard “poppet” checks and “swing” checks into a single high performance check module.

•Light weight engineered polymer components
•Modular for easy removal of complete check from body.
•Easily disconnect spring tension for safe check servicing.
•Replaceable Silicone Rubber Elastomer Disk.
•Excellent resistance to fouling

Skewed View
Low Flow Poppet Action

Poppet Action


•Initial 25% of check stroke is that of a poppet check
•Consistent static sealing
•Excellent resistant to fouling
•Reliable check closure
•Stable flow characteristics at lower flow rates

Swing Action


•Final 75% of check stroke is that of a swing check
•Minimal friction loss at high flow rates
•More linear flow path water through valve

High Swing Action

Bow-Seal™  Full Access Cover

Bow Seal 1
Bow Seal 3

The Patented Bow-Seal™ Full Access Cover ( US8844562) is pre-formed to cylindrical shape friendly to high fluid pressure. This allows the cover to be much thinner and lighter than traditional flat covers while still providing FULL and EASY access to Dual Action™ Check Modules. Additional features include:

• Light weight
• Simple removal
• No sliding seals
• Full access to valve internals
• No cumbersome and heavy couplings

Bow Seal 2
Bow Seal 4

Eccentric-Seal™  Shut Off- Valve

The only large diameter STAINLESS STEEL shutoff valve in the Backflow Industry. The Patented Eccentric-Seal™ Shut Off Valve ( US8887756) has a unique feature in that the inlet shutoff valve sealing disk seals on the downstream side of the valve operation shaft. This allows the #1 test cock to be located adjacent to the valve operation shaft reducing the overall length of the valve (and weight) by at least 2 inches. Additional features and benefits include:

• Self-centering disk seal
• Bolt-on replaceable shutoff disks
• Low torque valve operation
• Disk replacement does not require elastomer compression
• Elimination of seal around valve shaft
• Stainless steel shutoff disk
• The entire valve operation shaft is a single component

Eccentric Seal Shut Off Valve 1

Tamper Resistant  Test Cock

The Deringer tamper resistant ½” and ¾” ball valves are the first handle-less test cocks found on large diameter backflow devices in the industry. The top of the valve actuation stem has a unique shape that uses an independent custom wrench to open and close test cocks. All test cocks are lead free and meet the SDWA requirements.

Micro-Bypass™  Assembly

The Deringer 30/50 Micro Bypass™ Assembly is a type II bypass that utilizes an angled check valve and includes a standard 5/8 X 3/4 water meter for water use detection. It is the shortest, lightest and smallest bypass in the industry and the same bypass is used on all size Deringer 30/50 models. Constructed of lead free bronze, the micro bypass assembly meets all SDWA lead free standards.

Mirco Bypass Assembly 2½ - 4

Bypass-Angled  Check Valve

The bypass angled check valve has many features shown in the graphic below that are fundamental to creating the shortest, lightest and smallest bypass in the industry.

Bypass Angled Check Valve Image

Relief Valve

The Deringer 40/50 Relief Valve uses a stainless steel body, piston seal and stainless steel sensing line and has been designed to be the smallest and lightest Relief Valve in the industry. Unlike previous relief valve designs, the piston seal does not use the body of the relief valve to align itself properly when closing and opening and instead uses the guide pin on the piston. This will aid in making the Relief Valve resistant to build up and binding. All components of the relief valve are lead free and meet the SDWA requirements.

Relief Valve Image


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