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3" Deringer 30G

The 3" Deringer 30G Double Check Detector Assembly 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.

The smallest, lightest, most economical, best performing, and only all stainless steel backflow preventer. Period.

Approved in the Horizontal & Vertical Up Position.
Important Note: Install with FLEX Couplings or Flange Adapters Only. DO NOT use RIDGED Couplings!



Pro Price:

The Deringer 30G(x) Double Check Detector Valve Assembly (DCDA-II) 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 unathorized 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  BypassTM Assembly

The type-II bypass assembly is a new technology to the backflow industry and is used on Backflow Direct's Deringer 30 (DCDA-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 30G(x) Double Check Detector Assembly Valve shall utilize two independent Dual Action Check modules contained within a single valve housing constructed entirely of 304 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). Both gate valves shall include a stainless steel stem with 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 have a single full access service port and cover with an “inline” replaceable elastomer cover seal. The bypass assembly shall include a meter registering either gallons or cubic feet, a single check valve and required test cocks. Assembly shall be serviceable without special tools and approved for both horizontal and vertical applications.



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

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


More Information
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