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The 6" - 8" Second Check Valve Assembly can be used on 6" Deringer 20X - 50X, 8" Deringer 20 - 50, 6" Magnum 20X & 40X, and 8" Magnum 20 & 40 models. The 6" - 8" Second Check Valve Assembly comes pre-assembled from the factory ready for installation.

The 6" - 8" Second Check Valve Assembly includes:
  • Second Check Valve Assembly
  • Cover Seal O-Ring
  • Retainer Bolt O-Rings

Note: This check valve assembly is for the 6" - 8" Deringer 20(X) - 50(X) and Magnum 20(X) and 40(X) models only. The first and second check valves are not interchangeable.



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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
Deringer & Magnum First Check
Deringer & Magnum 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
Deringer & Magnum High Swing Action



Deringer Magnum First Check

Second Check Maintenance

The Second Check Maintenance Video provides a step by step procedure for maintaining a 6" - 8" Deringer & Magnum 20(X) - 50(X) backflow preventer second check.

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Backflow Direct Product Warranty

Product Warranty

This printable document provides information for the Backflow Direct one year warranty for Deringer and Magnum backflow preventers.

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