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4X”- 6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Maintenance of First Dual-Action Check Module
1. Use a #2 Philips Head Screwdriver to remove Tower
Screws (A) from the First Check Seat (B) The Double
Torsion Spring is captured and does not need to be
retained during maintenance.
2. After removing the Tower Screws (A) Examine the
Elastomer Disk (D) and Check Seat (E) for fouling or
damage.
3. Should Elastomer Disk (D) need replacement unscrew
Disk Retainer Screws (F) and remove Disk Retainer (G).
Carefully remove and replace Elastomer Disk (D).
When replacing Elastomer Disk (D) be certain that no
air, water or debris is trapped in the Clapper (H) cavity
behind the Elastomer Disk (D).
A
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC
4. Reverse the order of the above instructions to reassemble check.
• Elastomer Disk must be flat in Clapper (H) cavity before
tightening Disk Retainer Screws (F).
• Do not cross thread Disk Retaining Screws (F).
B
E
D
F
D
G
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H