evolution G-50 H
Service Manual
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Issue 3.2
Metering pumps
WARNING!
Before resolving any kind of defect, make sure all of the pushbuttons are
off, that the general switch is in shutdown position and that the unit is disconnected from
the power supply source. Never handle the inside of the control panel with the unit
connected to the power supply. The metering pumps are components that work under
pressure; do not open any connection or perform repair or maintenance work on
components subject to pressure until all of the pressures have been completely
eliminated.
If excessive pressure is caused in
the Isocyanate circuit or the Polyol
circuit, an alarm will be activated
that will be shown on the control
panel (3 for the Isocyanate and 4
for the Polyol).
Follow
the
recommended
procedure in the order indicated, to
try to solve the problem and avoid
costly repairs. Make sure all the
automatic switches and control
elements are in the correct working
position before determining the
existence of a fault.
PROBLEMS
SOLUTIONS
The pumps fail to maintain the pressure when the unit is shut down.
1
There are pressure differences between the metering pumps.
1-2-3
There is cavitation in the metering pump.
1-2-3
The metering pumps do not change direction.
4
The metering pumps fail to move and the direction indicator lights are out.
4-5
The movement of the metering pumps is erratic.
4
SOLUTIONS
1.
Loss in the Valve Ball
Observe the pressure gages to identify which pump fails to maintain the pressure and check the
direction indicator light to determine in which direction the pump fails to maintain the pressure. If
the lit lamp is the left hand one and the pressure is lost in the Polyol pump, check the discharge
valve ball of the Polyol pump; or check the inlet valve ball of the Isocyanate pump, if the
pressure loss is caused in the Isocyanate pump. If the lit lamp is the right hand one and the
pressure is lost from the Polyol pump, check the inlet valve ball of the Polyol pump; or check the
discharge valve ball of the Isocyanate pump, if the pressure is lost from the Isocyanate pump.
