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NT 1008-C00 07 18 P BA series e
8. BYPASS (continued)
8.1 Bypass operation
The compensated bypass operates like a valve, by auto-
matically limiting the discharge pressure at the value for
which it is adjusted.
When the discharge pressure reaches the adjusted pres-
sure of the spring, the valve
823
opens, thus permitting
the partial or total return of the liquid to the inlet side of
the pump.
The compensated bypass is used when the pump flow
is frequently diverted through its bypass, i.e. when the
discharge is closed, the compensated bypass is designed
to generate a very small increase of pressure, which
means that the motor will economically supply the
necessary additional power for specific working condi-
tions. It should be noted that the role of the bypass, as a
safety device, is limited to protecting the pump against
accidental over-pressure.
For all electric motors - unless the model used can hand-
le the increased load due to maximum overpressure -
(pump sending its flow through the bypass with the
spring tightened to the maximum) it is vital to provide
appropriate overload protection.
8.2 Bypass orientation
The single bypass only protects the pump in one direc-
tion of operation. Consequently it is necessary to check
that the pump’s direction of operation is correct by veri-
fying that the cap
827
is located on the inlet side. The
bypass must be reversed if in the wrong direction.
8.3 Bypass inversion
• Loosen the 2 screws
859
.
• Remove the bypass.
• Check the seals
858
and change them as necessary.
• Turn the bypass through 180°.
• Screw the 2 screws
859
, taking care to balance the
tightening so that the bypass remains vertical.
8.4 Bypass adjustment
• Loosen the lock nut
835
.
• Turn the adjustment nut
834
clockwise to increase the
discharge pressure and anticlockwise to decrease it.
• Once the adjustment is finished, screw the lock nut
835
.
Adjustment of the bypass is satisfactory when the flow
meets the pump’s requirements and when the motor
bears, without incident, either excessive energy
consumption or the power increase due to the overpres-
sure seen upon closing the discharge. This is how the
bypasses of our pump units are adjusted, as a function
of the information provided by our Technical Services.
Counterclockwise rotation
WARNING
INCORRECT SETTINGS OF THE PRES-
SURE RELIEF VALVE CAN CAUSE PUMP
COMPONENT FAILURE, PERSONAL INJURY,
AND PROPERTY DAMAGE.
Hazardous pressure
can cause
personal injury
or property damage.
Version with plug
Installing for
High Temperature
