Backflow Direct Deringer 20 Technical specifications

4X”– 6” Deringer 20/30 Maintenance Instructions
At Backflow Direct we are committed to making our products as easy to install as possible. We design for
most contingencies, but installation may be different based on your regional regulations or system design.
We are continually improving our products and instructions –please help us by providing recommendations
as to how we can improve or products or instructions.
If you have any difficulties at all, please give us a call. Thank you for purchasing our product!
IMPORTANT NOTE: We use Stainless Steel Hardware where possible. Therefore, it is best to have Silver Anti-
seize available to use on all non-wetted bolts—only a small amount is needed.
WARRANTY INFORMATION: Please visit our website for our official warranty www.backflowdirect.com/warranty
READ INSTRUCTIONS IN FULL BEFORE INSTALLATION.
QUESTIONS? CALL 916-760-4524 M-F 8:00 AM –4:30 PM PST
REV: A | 09/06/2019 | BD-INST-4X2030

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 2 of 20
Tools Required: This list is the recommended tools for ease of installation. Other versions of the same tool can be used. For
example, Allen Wrenches instead ofAllen Drive Sockets.
QUESTIONS: Please call us at 916-760-4524 M-F 8:00 AM –4:30 PM PST or email us at [e-mail]
#2 Philips Head Screwdriver
#2 Flathead Screwdriver
Adjustable Wrench
Ratchet
Wood Block - 2” x 4” x 5”
Wood Block – 1” x 2” x 16”
Backflow Direct Test Cock Wrench
Expanding Pipe Pliers
15/16” Socket
1 1/8” Socket

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC
Closing Shut-Off Valves Prior to Maintenance
1. Slowly rotate Shut-Off Valve #2 Handle (B) clockwise
to the closed position. Flag perpendicular to flow (A).
2. Slowly rotate Shut-Off Valve #1 Handle (C) clockwise
to the closed position. Flag perpendicular to flow (A).
Note: When yellow/orange position indicator flags are
parallel with the flow of water the shut-off valves are in the
open position. Before doing any maintenance be sure the
yellow or orange flow indicators (flags) are perpendicular
to the flow of water and valve body indicating shut-off
valves are in the closed position (A).
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Page 3 of 20
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Note
BC
A
A

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Opening Test Cocks and Bleeding All Pressure from the Line Before Maintenance
1. DO NOT OPEN Main Test Cock Number 1,
as it is still subject to line pressure.
2. Using the Backflow Direct test cock wrench or
a small adjustable wrench open (A) Main Test
Cock Number 4. (Test Cock is open when
wrench flats are parallel to water flow through
test cock)
3. Using a #2 Flathead Screwdriver open
Bypass Test Cock Number 2. (Test Cock is
open when screwdriver slot is parallel to
water flow through test cock (B) )
4. Using the Backflow Direct test cock wrench
or a small adjustable wrench open Main
Test Cock Number 3.
5. Using a #2 Flathead Screwdriver open
Bypass Test Cock Number 1.
6. Using the Backflow Direct test cock wrench
or a small adjustable wrench open Main
Test Cock Number 2.
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 4 of 20
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A
A
B
B

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Removing Access Port Cover Plate
1. Using a 15/16”socket wrench loosen all eight bolts on the access port
cover plate (A).
2. Remove bolts and tapered washers (B) and store in a safe place. Be
careful not to lose tapered washers as the access cover will not seal
properly without the tapered washers.
3. Remove access port cover plate (C). Do not remove Access Port O-ring
(D).
B
C
A
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 5 of 20
D

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Removing the First Dual-Action Check Module
1. Use a 15/16”Socket Wrench to loosen the check retainer bolts on
both sides of the valve body (A). Do not completely remove check
retainer bolts from valve body. Merely loosen the bolts until the
ends of the bolts are flush with the inner wall of the valve body(B).
This allows for easy removal of Check Modules.
2. Insert a flathead screwdriver between the inner valve body and the
First Check Module Flange (C), gently coax the First Check
Module in the downstream direction until the First Check Module
can easily be removed from the access port by hand.
A
B
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 6 of 20
C
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4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Removing the Second Dual-Action Check Module
1. Use a 1 1/8”Socket Wrench to loosen the Check Retainer Bolts on
each side of the valve body (A). Do not completely remove check
retainer bolts from valve body. Merely loosen the bolts until the
ends of the bolts are flush with the inner wall of the valve body(B).
2. Insert a flathead screwdriver between the inner valve body and the
Second Check Module Flange (C), gently coax the Second Check
Module in the upstream direction until the Second Check Module
can easily be removed from the access port by hand.
A
A
C
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 7 of 20
B
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4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Disassembly and Maintenance of By-Pass Check Valve
1. Use an adjustable wrench to
rotate Check Cover (A)
counterclockwise to remove.
2. Examine Cover Plate O-ring (B)
for damage or fouling.
3. Remove Spring (C).
4. Remove Check Poppet
Assembly (D) and examine for
damage or fouling.
5. Examine seat cage (E) for
damage or fouling to the Sealing
Seat. Do not remove unless the
seat cage is being replaced.
6. Reverse the order of above
instructions to reassemble By-
Pass Check Valve.
B
C
D
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC
A
Page 8 of 20
D

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct,
LLC
Disassembly and Maintenance of By-Pass Check Valve (continued)
1. To replace a damaged Red Silicone Poppet Disk, use a #2 Philips Head
Screwdriver to remove the Disk Retaining Screw (A).
2. Remove Disk Retaining Washer (B).
3. Use a Flathead Screwdriver to remove the gasket from Poppet Cavity (C).
4. Install new Red Silicone Poppet Disk (D).
5. Reverse the order of the above instructions to reassemble Check Poppet
Assembly.
6. Reverse the order of the instructions on the previous page to reassemble
Bypass Check Assembly.
A
A
C
D
B
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 9 of 20

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Removing Bypass Meter
1. Using the Ball Valve Handles close the #2 Bypass Ball Valve (A) and
then #1 Bypass Ball Valve (B). (Ball Valve is closed when “T” handle is
perpendicular to water flow through Ball Valve).
2. Using a #2 Flat Head Screwdriver open Bypass Test Cock #2 (C) and
then open Bypass Test Cock #1 (D). (Test Cock is open when
screwdriver slot is parallel to water flow through Test Cock).
3. Using a large wrench or adjustable pliers unscrew and retract Bypass
Meter Coupling Nuts (E) . Remove the Gaskets (F) on both sides of
Bypass Meter.
4. Gently remove Bypass Meter (G) from line. It is OK if the bypass
fittings move slightly during the removal process.
5. Reverse order of above instructions to reinstall Bypass Meter.
Remember install Gaskets (F) before threading Meter Coupling Nuts
into place.
B
A
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC
C
D
E
E
E
F G
Page 10 of 20
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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
DG
Page 11 of 20
H

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
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 12 of 20
Note: The diagram below shows the correct orientation of the First Dual-Action Check Module when being re-attached to the seat. In
order to maintain the performance of the valve pay attention to the proper orientation of the check module.

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Maintenance of Second Dual-Action Check Module
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC
A
B
E
D
F
D
G
Page 13 of 20
1. Use a #2 Philips Head Screwdriver to remove Tower
Screws (A) from the Second 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).
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).

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Maintenance of Second Dual-Action Check Module
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 14 of 20
Note: The diagram below shows the correct orientation of the Second Dual-Action Check Module when being re-attached to the seat.
In order to maintain the performance of the valve pay attention to the proper orientation of the check module.

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Installing Second Dual Action Check Module
1. Insert Second Check Module (A) into Access Port (B) with Second Check
Towers (C) pointing downstream. Push Second Check Module (A)
downstream into Valve Sealing Ring (D) until Check O-ring (E) rests against
Valve Sealing Ring (D). Coax Second Check Module (A) into its fully seated
position by hand.
2. Alternatively place 2”x4”piece of wood cut to 5”length (F) against the
backside of the Second Check Seat Ring (G). Using a 1”x4”piece of wood
cut to 16”length (H) as a lever between Access Port Wall the 2”x4”(F) gently
coax the Second Check Module (A) into its fully seated position.
3. Be certain Second Check Module (A) is fully seated and Check O-ring (E) is
NOT “fish mouthed” or damaged.
4. Tighten the Second Check Retaining Screws (I) ONLY AFTER the First Check
Module (A) as been installed.
Binding Not Binding
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 15 of 20
WARNING: The Second Check Module must be fully
seated to ensure Retainer Screws do not bind against
Check Seat. Binding Retainer Screws against Check Seat
will result in permanent damage to Second Check Modules.
F
G
H
I
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B
A
C
D
E

4X”-6” Deringer 20/30 Maintenance Instructions
WARNING: The First Check Module must be fully
seated to ensure Retainer Screws do not bind
against Check Towers. Binding Retainer Screws
against Check Towers will result in permanent
damage to First Check Modules.
1. Insert First Check Module (A) into Access Port
(B) with First Check Towers (C) pointing
downstream. Push First Check Module (A)
upstream into Valve Sealing Ring (D) until
Check O-ring (E) is resting against Valve
Sealing Ring (D). Coax First Check Module (A)
into its fully seated position by hand.
2. Alternatively, using a piece of 1”x4”wood cut to
16”length (F) as a lever between the Second
Check Seat (G) and the First Check Towers
(C), coax the First Check Module (A) into its
fully seated position.
3. Be certain First Check Module (A) is fully
seated and Check O-ring (E) is NOT “fish
mouthed” or damaged.
4. Now fully tighten the First and Second Check
Retaining Screws (I) .
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Installing First Dual-Action Check Module
Not BindingBinding
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 16 of 20
I
A
B
C
D
E G
F
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4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Installing Access Port Cover
1. It is best to never remove the Access Port O-ring (A). Should the Access
Port O-ring (A) become dislodged, simply insert it back into Access Port
Groove (B).
2. Slide the Access Port Cover (C) into place being certain that Access Port O-
ring (A) does not become dislodged during the process.
3. Insert Cover Bolts (D) and Tapered Washers (E) into Tapered Cover Holes
(F). Tapered Washers (E) must be properly installed or the Access Port
Cover (C) will not seal under pressure.
4. Use 15/16”Socket Wrench (G) to tighten the 4 center Cover Bolts (D)
alternating from one side of the valve to the other. Then Tighten the four
corner bolts alternating from one side of the valve to the other.
A
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 17 of 20
C
E
D
G
F
B

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Close Test Cocks and Double Check all Closing/Sealing Mechanisms
1. Using the Backflow Direct Test Cock Wrench or a small
adjustable wrench close Main Test Cocks Number 1, 2
and 3 (A). (Test Cock is closed when wrench flats on
stem are perpendicular to water flow through Test Cock)
2. Using a #2 Flathead Screwdriver Close Bypass Test Cock
Number 1 and 2 (B). (Test Cock is closed when
screwdriver slot on stem is perpendicular to water flow
through Test Cock)
3. Use the “T” handles to open bypass Ball Valve Number 1
(C) and then open bypass Ball Valve Number 2 (D). (Ball
Valve is open when “T” handle is parallel to water flow
through Ball Valve)
4. Double check to be certain of the following:
•All Cover Bolts are Tightened (E)
•Bypass Check Valve Cover is Tightened (F)
•Bypass Meter Coupling Nuts are Tightened (G)
A
A
B
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC
B
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Page 18 of 20
D
E
C
GF

4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Open Shut-Off Valves to make Backflow Preventer Functional
1. Slowly rotate the Number 1 Shut-Off Valve Operation
Handle (A) counterclockwise to the open position. (Shut-Off
Valve is open when yellow/orange position indicator flags
are parallel to the mainline water flow)
2. Slowly rotate the Number 2 Shut-Off Valve Operation
Handle (B) counterclockwise to the open position.
Note: Yellow/Orange Position Indicator Flags must be parallel
to mainline water flow for Backflow Valve to be functional (C).
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC
A
B
CC
Page 19 of 20
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4X”-6” Deringer 20/30 Maintenance Instructions
BD-INST-02030 | Rev C | 12/22/2015 | Copyright 2011 Backflow Direct, LLC
Important Note: If a Deringer is going to be installed outdoors and the tamper switches will not be wired into the fire alarm system,
the wires will need to be cut, and a plug will need to be installed to protect the internal components of the gear box.
Step 1: Using wire cutters, cut the wires coming out of the gearbox as close to the gearbox as possible.
Step 2: Use a piece of thread seal tape to seal the threads on the ½” NPT plug
Step 3: Using an Allen wrench, install and tighten the ½” NPT plug into the same threaded hole where the wires were previously cut.
BD-INST-4X2030 | Rev A | 09/06/2019 | Copyright 2011 Backflow Direct, LLC Page 20 of 20
IMPORTANT NOTE