novaG
– 2K
Service Manual
17/23
Issue 1.6
To determine if the decompensation occurs as a result of an obstruction or as a result of a
problem in the pumping system, project with the gun, observe the pressure indicated by the
manometer corresponding to the missing component and compare it with the pressure indicated
by the manometer of the other component: if the pressure of the missing component is greater,
decompensation is a consequence of an obstruction, if the pressure is lower the
decompensation is a consequence of a problem in the pumping system
3. Cavitation
Cavitation occurs when the proportioning pump requires a larger volume of material than that
supplied by the feeding system, causing the formation of a vacuum in the proportioning pump.
The causes of cavitation are the following:
a) High viscosity: the polyurethane foaming systems normally require a minimum transfer
temperature of 12º C; at lower temperatures, the product increases in viscosity, making
the pumping more difficult. When the ambient conditions prevent the products from
being maintained at a minimum temperature of 12º C auxiliary heating elements must
be used to condition the products as the minimum temperature required for the transfer.
b) The product inlet filter is obstructed (see Maintenance).
c) The inlet ball valve has leaks as a result of wear or possible faults in the ball or the
closing surface of the bushing, which means that part of the material supplied returns to
the supply tank and that the proportioning pump supplies a smaller volume of material
in the discharge cycle, causing an incorrect ratio.
4. Fault in the Direction Change Micro
The pneumatic cylinder that drives the supply pumps has two magnetic position detectors for
making the change of direction. Each detector includes an led to indicate when it is active. Any
accidental movement of the detection position will prevent the pumps from making the change
in direction, which will oblige the detector to be put back into the correct position by using the
gauge supplied with all of the accessories.
5. Rising Movement Pressure Regulator
During the up stroke, the pumps must self-aspirate the products through the feeding hoses.
Adjust the up-stroke regulator so that the pressure of the proportioning pumps is the same in
both directions.