2 1/2" DERINGER 50G (RPDA)
The 2½" Deringer 50G 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, lightest, 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:
$3,539.00Pro Price:
$2,529.00NEVER install an RP or RPDA in a location where any amount of discharge from the Relief Valve will cause property damage. For an indoor, pit, vault, mechanical room or enclosure installation of an RP or RPDA, an auxiliary drain (separate and independent of the Air Gap Assembly) is REQUIRED and MUST be properly sized for the Maximum Relief Valve Discharge Rate (see specifications below) corresponding to the system/supply pressure. Backflow Direct shall not be responsible for any damage caused by lack of auxiliary drain, location of auxiliary drain or undersized auxiliary drain. If the buyer is unwilling to meet this requirement please DO NOT purchase this product.

NEVER install an RP or RPDA in a location where any amount of discharge from the Relief Valve will cause property damage. For an indoor, pit, vault, mechanical room or enclosure installation of an RP or RPDA, an auxiliary drain (separate and independent of the Air Gap Assembly) is REQUIRED and MUST be properly sized for the Maximum Relief Valve Discharge Rate (see specifications below) corresponding to the system/supply pressure. Backflow Direct shall not be responsible for any damage caused by lack of auxiliary drain, location of auxiliary drain or undersized auxiliary drain. If the buyer is unwilling to meet this requirement please DO NOT purchase this product.


The Deringer 50G 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.

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

Engineering & Specifications
The Deringer 50G(X) Reduce Pressure Detector (RPDA-II) Valve shall utilize two independent Dual Action Check modules contained within a single valve housing constructed of entirely of stainless steel. 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. Valve assembly shall include two resiliently seated and inline serviceable AWWA C509 gate valves of type outside yoke and stem (OS&Y). Gate valves shall utilize a stainless steel stem with a pre-machined groove for installation of supervisory tamper switches. Assembly test cocks shall be handle-less and operate via a tamper resistant actuator. Assembly shall utilize a single full access service port and a cover with an “inline” replaceable elastomer seal. Relief valve shall operate without the use of sliding seals and shall be constructed entirely of stainless steel. The bypass assembly shall include a meter registering gallons or cubic feet, a single check valve and test cocks. Assembly shall be serviceable without the use of special tools.
Maximum Relief Valve Discharge Rates

Air Gap Assembly will capture and evacuate light water discharge from the Relief Valve caused by daily fluctuation in system/supply pressure. An Air Gap Assembly will NOT capture and evacuate the Maximum Relief Valve Discharge Rate caused by catastrophic valve or system failure. An auxiliary drain (separate and independent of the Air Gap Assembly) is REQUIRED and MUST be properly sized for the Maximum Relief Valve Discharge Rate. Backflow Direct shall not be responsible for any special, consequential or incidental damages, including without limitation, repair costs, lost profits, property damage, or any other costs resulting from labor charges, delays, vandalism, negligence, fouling caused by foreign material, adverse water conditions or any other circumstances, caused by lack of auxiliary drain, location of auxiliary drain or undersized auxiliary drain.
Retrofit Spool Program
The Backflow Direct Retrofit Program is the easiest spool ordering process in the industry!
Simply go to our online Retrofit Spool Form and submit a few pieces of needed information. Backflow Direct will take the information provided and create a CAD drawing of the completed retrofit package along with a quote for you to review.
When you are ready to order, simply confirm by email and BackFlow Direct will start your order. It really is THAT easy!
BackFlow Direct's retrofit program video provides an easy to understand demonstration of the ordering process from start to finish. Please feel free to contact us with any questions at [email protected]
TECHNOLOGY
TopTrue-Seal™ 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 and Magnum RP model. 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.


Poppet Action
Features:
- 100% of check stroke is that of a poppet check
- Consistent static sealing
- Excellent resistant to fouling
- Reliable check closure
- Stable flow characteristics at ALL flow rates
Dual-Action™ 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


Poppet Action
Features:
- 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
Features:
- 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.

Bow-Seal™ Full Access Cover
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

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.

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.

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.
