172-65634MAJ-03 (A-DR20) 6 Oct 2021
7
4. Recommended Straight Pipe Runs
In order to ensure a stable flow of air, the piping upstream and downstream of the
A-DR20 must be straight runs. If the A-DR20 is installed either directly before or
after an elbow or control valve, unevenness in flow may result in chattering and
unstable pressure.
To ensure a stable air flow, it is recommended that the A-DR20 be installed on
straight runs of piping, as illustrated below.
(1) Inlet (primary side) of the A-DR20
NOTE: d = pipe diameter
Maintain a straight piping
run of
10 d or more
when a manual valve, a
strainer or an elbow, etc.
is installed.
(Example: if nominal size
is 25 mm (1 in), have
250 mm (10 in) or more)
Maintain a straight piping
run of
30 d or more
when an automated
valve (on-off valve) is
installed.
(Example: if nominal size
is 25 mm (1 in), have
750 mm (30 in) or more)
Maintain a straight piping
run of
30 d or more
when another pressure
reducing valve is
installed. (Two-stage
pressure reduction)
(Example: if nominal size
is 25 mm (1 in), have
750 mm (30 in) or more)
(2) Outlet (secondary side) of the A-DR20
Maintain a straight piping
run of
15 d or more
when a manual valve, a
strainer or an elbow, etc.
is installed.
(Example: if nominal size
is 25 mm (1 in), have 375
mm (15 in) or more)
Maintain a straight
piping run of
30 d or
more
when a safety
valve is installed.
(Example: if nominal size
is 25 mm (1 in), have 750
mm (30 in) or more)
10d or more
A-DR20
Valve, elbow,
strainer, etc.
A-DR20
Valve, elbow,
strainer, etc.
Less than
10d
Automated
Valve
A-DR20
30d or more
A-DR20
Automated
Valve
Less than
30d
30d or more
A-DR20
Pressure
Reducing
Valve
A-DR20
Pressure
Reducing
Valve
Less than
30d
A-DR20
15d or more
Valve, elbow,
strainer, etc.
A-DR20
Less than
15d
Valve, elbow,
strainer, etc.
A-DR20
30d or more
Safety Valve
Safety Valve
A-DR20
Less than
30d
