Type Of System; Closed Vessel Plant; Safety Valves - Dal Zotto Valli idro Manual Del Usuario

Whenever the generators lack a device, those missing can be installed on the generator flow pipe, within a distance no greater
than 1m from the machine.
cOMPOnent
Temperature safety sensors
Missing devices because not as per standard
The domestic heating appliances with automatic feeding must: be equipped with a fuel block thermostat or with a cooling
circuit set up by the appliance manufacturer.
The cooling circuit must be activated by a thermal safety valve, in order to ensure that the limit temperature set forth by the
Standard is not exceeded.
Connection between the power supply unit and the valve must be free from interceptions.
The pressure upstream from the cooling circuit must be at least 1.5 bar.

tyPe Of SySteM

There are two different types of system:
Š Open vessel plant and closed vessel plant.
The product has been designed and realised to work with closed vessel systems.

cLOSeD veSSeL PLAnt

System in which the water it contains is not in direct or indirect communication with the atmosphere. Generally, the closed
vessel system has one of the following expansion vessels:
Š Pre-loaded closed expansion vessel with membrane impermeable to the passage of gases.
Š Automatic closed expansion system with compressor and membrane impermeable to the passage of gases.
Š Automatic closed expansion system with transfer pump and membrane impermeable to the passage of gases.
Š Expansion system without diaphragm.
generALity
The closed systems must have:
Š Safety valve
Š Pump control thermostat
Š Acoustic alarm activation thermostat
Š Temperature indicator
Š Pressure indicator
Š Acoustic alarm
Š Adjustment automatic circuit breaker switch
Š Automatic circuit breaker switch (block thermostat)
Š Circulation system
Š Expansion system
Š Safety dissipation system incorporated with the generator with thermal safety valve (self-activated), whenever the
appliance does not have a temperature self-adjustment system

SAfety vALveS

The load capacity of the safety valve must allow the discharge of a quantity of vapour, not lower than: Q / 0.58 [kg/h] where: Q
is the useful outlet power to the generator water expressed in kilowatt. The diameter of the minimum net transversal section
of the valve inlet must not be lower than 15 mm. The valve load pressure, equal to the calibration pressure, increased by the
overpressure, cannot exceed the maximum exercise pressure of the heat generator. The designer must check that the maximum
pressure existing in every point of the system, does not exceed the maximum exercise pressure of its every component . The
safety valve must be connected to the upper part of the heat generator or outlet pipes, very close to the generator. The length
of the piping between the generator coupling and the safety valve must not exceed 1 m. The piping connecting the safety valve
to the heat generator must not be interrupted and must not have, in any point, a cross-section lower than than that of the safety
46
DiStAnce
On the machine or not exceeding 30 cm
Not exceeding one metre, on the flow pipe
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