American Backflow Deringer 20 User manual

20, 20X, 20G, 20GX
2” –8”

Product Overview
Production of the Model 20 (DCA) began in 2014.
The “X” and “GX” series come in 4” and 6” sizes
only. This indicates internal check valves that are
larger than line size. For example 6” uses 8” parts.
The “G” series indicates gate valve shut off valves.

Single Access Cover Removal
The access cover is
secured by bolts and
o-ring sealed.
There is no spring load
on the cover.
Remove bolts and
tapered washers.

Check Valve Removal
Modules are o-ring
sealed and secured by
retaining bolts located
on the outside of the
valve body.
2”-4” sizes: Loosen the
six 7/32” allen bolts until
they are flush with the
inner wall of the body.
6”-8” sizes: Loosen the
six retaining bolts.

Check Valve Removal
Modules are o-ring
sealed.
Remove check 1 first,
then check 2.
Using a flat blade
screwdriver, gently pry
the module out of the
body.

Check Disc Replacement
Remove 4 tower screws on
the front or back of the check
module.
The torsion spring is
captured and does not need
to be retained.
Remove the tower from the
check seat.
Remove retaining screws
from the disc retainer.

Check Seat Service
The check seat is part
of the module.
If seat is damaged, the
entire module will have
to be replaced.

First Check Valve Reassembly
Proper orientation of
the tower and seat is
critical for First
check operation.
Re-attach the tower
to the seat with the
spring arms and
seat protrusions
facing UP.

Second Check Valve Reassembly
Proper orientation of
the tower and seat is
critical for Second
check operation.
Re-attach the tower to
the seat with the spring
arms facing DOWN
and seat protrusions
facing UP.

Second Check Installation
Check 2 must be
installed before check 1.
Insert check 2 into body
with tower pointing down
stream.
Push check into place
until o-ring is fully seated.
Do not tighten retaining
screws until check 1 is
installed.

First Check Installation
Check 2 must be
installed before check 1.
Insert check 1 into body
with tower pointing
down stream.
Push check into place
until o-ring is fully
seated.

Check Valve Reassembly Notes
Once check 1 and
check 2 are fully
seated, tighten the
6 retaining bolts on
the outside of the
body.
Make sure that the
retaining bolts do
not bind against the
check valves.

Access Cover Reassembly
Place the access cover on the
main body.
Make sure cover o-ring
maintains the correct position.
Insert cover bolts and tapered
washers.
Tapered washers are necessary
for water tight seal.
Tighten the cover bolts
sequentially and by alternating
from side to side.