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9. ANTI-FLOODING DEVICE
The cover installed on the pressure modulating switch makes it possible, by means
of the special tube, to collect and carry to the drain tub any water which may exit
the boiler to due any malfunction of the machine.
10. PUMPING SYSTEM
This is a component that serves the purpose of feeding the machine, raising the
water pressure to 8-9 bar for the delivery of the coffee and for automatic filling
of the boiler.
11. VALVE GROUP
The valves are devices whose purpose is to ensure the safety and proper operation
of the machine.
11.1 NEGATIVE PRESSURE VALVE
The purpose of the negative pressure valve is to prevent the backflow of liquids
through the steam nozzle when they are being heated. Furthermore, the excess
air is eliminated inside the boiler during the heating phase of the machine.
11.2 SAFETY OR PRESSURE RELIEF VALVE
The pressure relief valve guarantees that the pressure in the boiler does not go
above 2 bar. If there is a malfunction, the capacity of the valve is such that it can
eliminate all of the excess pressure in the valve.
11.3 EXPANSION VALVE - NON-RETURN VALVE
This is a valve consisting of an expansion valve and a non-return valve.
•
Expansion valve: the cold water sent from the pump to the heat exchangers
is heated. This heating causes an increase in the volume of water. To limit
increases of pressure in the hydraulic circuit, the valve limits the maximum
internal pressure of the circuit to 12 bar.
•
non-return valve: Its function is that of preventing the back flow of water
from the exchangers in the hydraulic circuit.
NOTE
On all machines with four groups, two pressure relief valves are installed.
espresso coffee machine - instructions for technician
valve
EXPANSION
NON-RETURN
R
valve
17
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