TLV DR20 Manuel D'utilisation page 10

5. Piping and Installation
CAUTION
5.1 Recommended Straight Pipe Runs
If a pressure reducing valve is installed either directly before or after an elbow or control valve,
unevenness in flow may result in chattering and unstable pressure.
To ensure stable flow, it is recommended that the pressure reducing valve be installed on
straight runs of piping, as illustrated below.
○ Inlet (primary side) of the pressure reducing valve
1
• 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"),
have 250 mm (10") 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"),
have 750 mm (30") or more)
○ Outlet (secondary side) of the pressure reducing valve
2
• 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"),
have 375 mm (15") 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"),
have 750 mm (30") 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"),
have 750 mm (30") or more)
• Installation, inspection, maintenance, repairs, disassembly, adjustment and
valve opening/closing should be carried out only by trained maintenance
personnel.
• Take measures to prevent people from coming into direct contact with
product outlets.
• Install for use under conditions in which no freeze-up will occur.
• Install for use under conditions in which no water hammer will occur.
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d = pipe diameter
10 d or more
30 d or more
15 d or more
30 d or more
30 d or more