2 1/2" Deringer 20
Backflow Direct's 2.5" Deringer 20 Double Check DC DCA Backflow Preventer
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The 2 ½" Deringer 20 Double Check prevents non-health hazard pollutants 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.
Approved in the Horizontal & Vertical Up Position.

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

MSRP: $1,179.00
Pro Price: $939.00

Product Code: BFD-2520

Specifications Technology Downloads

The Deringer 20 Double Check Valve Assembly is designed to prevent non-health hazard pollutants from entering the potable water supply system caused by backpressure and/or backsiphonage conditions.

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 20 Double Check (DC) valve shall utilize two independent Dual Action 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. Assembly shall be serviceable without special tools and approved for both horizontal and vertical applications.

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

  0 of 0 people found the following review helpful:
2 1/2" Deringer 20 Install at Chruch March 17, 2016
Reviewer: Bob Williams from Huntingtron, NY United States  
As a licensed professional engineer and Church member I needed to address the notification received that our existing valveless back flow device failed required annual testing.The Church's sprinkler system is housed in a small storage closet installing a new device there seemed plausable. However, the limited space available would not accommodate a conventional device with two valves and dealing with a weight of over 200 pounds would be difficult.
However, the Deringer 20 device, being 18.7 inches in length, weighing 42 pounds and using IPS grooved ends, could be accomodated. Actual installation was simple, quick, and without any difficulties.

Being a professional engineer, I throughly inspected the device before installation and found it to a significant improvement and less costly compared to conventional devices that I have encountered in my almost 50 years experience in drinking water programs.    

Robert R. Williams, P.E.

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