CO
2
NNEXT
rev.01
EN
69 / 293
2.2.
Devices and Solutions for protection
2.2.1.
Passive safety devices
For the partly-completed machine the devices and constructive solutions described below were adopted:
x
fixed guards close to the moving parts;
x
external fairing with fixed access doors (if present);
x
safety signs corresponding to the guards of the partly-completed machine.
2.2.2.
Active safety devices
For the partly-completed machine, the active safety devices described below were adopted:
x
Maximum safety pressure switch for each automatic reset compressor (PSH) or for specific versions
with safety pressure switch for each manual reset compressor (PZH);
x
Safety valve on the MT and LT circuit low pressure side (if present);
x
Safety valve(s) on the intermediate receiver;
x
Safety valve on the high pressure side, (if present).
The valve calibration is shown on the valves themselves and has been dimensioned on the basis of the
indications of the EN 13136 standard.
ATTENTION: It is absolutely forbidden to modify the calibration of the safety pressure switch and/or to inhibit
its operation.
2.2.3.
Protection systems
The system is equipped with protections to safeguard anomalous situations acting on both the pressure and
voltage circuits.
Excessive pressure inside the refrigeration circuit
The safeguard against excess pressure inside the refrigerating circuit during discharge, which beside
compromising system operation, can also be dangerous to the personnel, has two intervention steps:
x
When the pressure reaches values exceeding the acceptable conditions, values determined
according to the characteristics of the refrigerant adopted, from the sizing of the system and from the
characteristics of the compressor, the maximum pressure switches intervene which cause the
associated compressor to stop. Resetting the system operation can occur automatically or through
manual intervention, which should only be carried out after having removed the fault cause. The
resetting differs on the basis of the machine characteristics.
ATTENTION: It is strictly forbidden to change calibration of the high pressure safety switches once
testing has been carried out during initial start-up.
x
Regarding all the safety valves on the low pressure and high pressure side; the calibration is shown on
the valve itself and has been calculated on the basis of the indications of the EN 13136 standard. The
intervention of these devices causes leakage and loss, in whole or in part, of the refrigerant loading
into the system.
