20
7425MUM651
Model: QBS
- Use and Maintenance Manual
Rev. 02
Safety Devices
QBS chillers have a series of safety devices that limit the machine's temperature and pressure values
to ensure that it operates within the expected 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 condensation pressure
High-pressure switch
Compressor output pipe
Low water temperature
Anti-freeze thermostat
Water exit from the
evaporator
Frequent compressor start-ups
Anti-circulation timer
Electronic controller
Low water level in the tank
Water-level sensor
Tank
Legend: n.a. not available – Opt.: optional
When they reach their calibration value, most of the security devices 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.
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 gauge
30 barg//435 psi
23 barg//334 psi
Manual
Anti-freeze thermostat
4°C//39,2°F
6°C//42,8°F
Semiautom.
Water-level sensor
--
--
Semiautom.
Anti-circulation timer*
5 min.
--
--
* This is a function of the electronic controller that prevents the same compressor from stopping and
starting too frequently: at least 5 minutes must elapse between one compressor’s power up and the
next.
