Easy Spray-H
Service manual
38/48
Issue 1.9
Ref. NR-00088-ENG
http://www.gamapur.com/
To ascertain whether the pressure imbalance is caused by an obstruction or by a problem in the
pumping system, operate the spray gun and check the reading on the pressure gauge of the
missing component. Compare this reading with the pressure indicated on the other component’s
pressure gauge: if the pressure of the missing component is higher, the pressure imbalance is
caused by an obstruction; if it is lower, the imbalance is due to a problem in the pumping
system.
3. Cavitation
Cavitation occurs when the proportioning pump requires a greater volume of material than the
feed system is supplying, giving rise to the formation of voids in the proportioning pump. There
are three possible causes of cavitation:
a) High viscosity. Polyurethane foam spray systems normally require a minimum transfer
temperature of 12ºC: at lower temperatures, the viscosity of the component products
increases and it is more difficult to pump them. When ambient conditions do not allow
the component products to be kept at the minimum temperature of 12ºC, auxiliary
heating equipment must be used to keep the component products at the minimum
required transfer temperature.
b) The product intake filter is clogged (see Maintenance).
c) The intake ball valve is leaking as a result of wear or defects in the ball or the closing
surface of the bushing, which causes some of the material to return to the tank.
Therefore the volume of material delivered by the proportioning pump in the discharge
cycle is lower than required, giving rise to an incorrect product ratio.
4. Fault in the direction change sensor
The hydraulic cylinder which drives the proportioning pumps is fitted with two inductive sensors
which control its change of direction. Accidental displacement from the detection position will
mean the pumps do not change direction, and so the sensor has to be returned to it correct
position.
The only way to adjust the position of the sensors is by inserting them to a greater or lesser
degree in the cylinder body.
5. Tank empty
As there is no way of visually checking the level of product in the tanks during the normal
operation of the unit, there is a risk that air will enter the circuit if the level in one tank is too low.
This will cause the pumping system to malfunction.
If this problem occurs, purge the air from the circuit as described in the corresponding section
on
p.20
(hoses with recirculation) or
p.23
(heated hoses).