Setting The Needle-Type Throttles In The Bypass - Wilo FLA Série Notice De Montage Et De Mise En Service

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8.1.2 Setting the needle-type throttles in the bypass

The needle-type throttle is set in the factory to a
specific volume flow and is secured against unau-
thorised activation.
If the needle-type throttle has to be reset, we rec-
ommend proceeding as follows:
The volume flow for the relevant pump's minimum
flow rate can be set using the calibration method.
To calibrate, you require an additional draw-off
connection in the bypass line (Fig. 6a/b, item 18,
feeder pipe). Select valves with minimal pressure
Pump type Volume flow
to be set
m³/h
HELIX V16.. 1.6
HELIX V22.. 2.2
HELIX V36.. 3.6
HELIX V52.. 5.2
MVI70.. 7.0
MVI95.. 9.5
Table 6
(*) Bypass connection ... Screwed connection with
male thread R (tapered pipe thread) and female
thread G (cylindrical pipe thread).
The minimum nominal diameter of the bypass
applies for a maximum bypass line length of 5 m. If
a longer bypass line is necessary, the minimum
nominal diameter of the entire bypass line should
be increased by one nominal diameter for each
new 5 m (or part thereof).
38
Bypass
connection (*)
R G
3/4" 1"
3/4" 1"
1 1/4" -
1 1/4" -
1 1/2" 1 3/4"
1 1/2" 1 3/4"
losses for the shut-off devices. During the cali-
bration operation, ensure that there is no reduc-
tion by other consumers in the downstream
system.
The minimum nominal diameter, calibration time
and volume flow to be set depend on the pump
used. See Table 6 below:
Calibration at (litre)
10L 20L
seconds
23s 45s
16s 33s
10s 20s
7s 14s
5s 10s
4s 8s
Minimum
nominal
diameter of
bypass
30L
68s DN20
49s DN20
30s DN25
21s DN32
15s DN40
11s DN50
WILO SE 08/2019