FRIULAIR PURESTREAM CHILLERS CWE-Q 041, Use And Maintenance Manual

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7425MUM753 Model: CWE-Q - Use and Maintenance Manual Rev. 15
6
S
AFETY
D
EVICES
CWE-Q chillers have a series of safety devices that limit the machine's temperature and
pressure values to ensure that it operates within the anticipated limits and to avoid
dangerous situations.
Here is a list of dangerous situations, including the relative safety device and its location.
Dangerous situation Safety device Location
High condensing pressure High pressure switch Compressor discharge pipe
High condensing pressure High pressure prevention system Electronic controller
Low evaporation pressure Low pressure transducer Compressor suction pipe
Low evaporation pressure Low pressure prevention system Electronic controller
Low water flow-capacity Water differential pressure switch Evaporator heat exchanger
Low water temperature Anti-freeze thermostat
Water exit from the evaporator heat
exchanger
High water pressure Safety valve (optional) Water tank (optional)
Frequent compressor start-
ups
Anti-circulation timer Electronic controller
Low water level in the tank Water level sensor (optional) Water tank (optional)
When the safety devices reach their setting value, most of them trigger an alarm managed by
the electronic controller.
For some safety devices, once the cause of the alarm times out, the machine
resumes operation automatically as soon as the reset value is reached. Others must
be manually reset to restart the machine (also see paragraph 5.11 Alarms ).
The following paragraph lists the characteristics of each safety device.
6.1 C
ALIBRATION OF THE SAFETY DEVICES AND TYPE OF REARM
Safety device Intervention value Reset value Type of rearm
High pressure switch 41,5 barg // 602 psi 33 barg // 478 psi Manual
Low pressure transducer 5,8 barg // 84 psi 6,8 barg // 99 psi Semiautomatic
High pressure prevention* 40 barg // 580 psi 38 barg // 551 psi Automatic
Low pressure prevention* 6,8 barg // 99 psi 7,8 barg // 113 psi Automatic
Water differential pressure switch 85 mbar // 1,24 psi 105 mbar // 1,53 psi Manual
Anti-freeze thermostat 4°C // 39,2°F 8°C // 46,4°F Semiautomatic
Water safety valve 6 barg // 87 psi --- ---
Anti-circulation timer** 5 min. --- ---
* Only active on units with more than one compressor: consists in reducing the number of
functioning compressors to 1 until the condensation pressure falls below the reset value
again
.
** This is a function of the electronic controller that prevents the compressor from stopping
and starting too frequently: at least 5 minutes must elapse between the compressor’s power
up and the next.