Samon GLACIAR MIDI, User Manual

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5.6 Cleaning the device
Clean the detector with a soft cloth using water and a mild detergent. Rinse with water. Do not use alcohol, degreasers,
sprays, polishes, detergents, etc.
6
FURTHER INFORMATION
6.1 Sensor operating principle
6.1.1
Semiconductor sensors
Semiconductor or metal-oxide-semiconductor (MOS) sensors are very versatile and can be used in a wide range of
applications: they can measure both gases and vapours at low ppm and combustible gases at higher concentrations. The
sensor is made from a blend of metal oxides. These are heated to a temperature between 150 °C and 300 °C, depending
on the gas to be detected. The operating temperature and composition of oxides determines the selectivity of the sensor
with respect to different gases, vapours and refrigerants. Electrical conductivity increases significantly as soon as gas or
vapour molecules come into contact with the sensor’s surface by diffusion.
When the molecules of the selected gas come into contact with the sensor’s surface, the conductivity of the
semiconductor material increases significantly in proportion to the concentration of gas. Consequently, the current
running through the sensor also varies. Water vapour, high ambient humidity, temperature fluctuations and low oxygen
levels can alter the readings, giving a higher concentration than the actual level.
By using this technology,
GLACIÄR MIDI allows the gas detected to be selected based on its category. Gases are divided
into three categories or groups. Group 1 includes R32 gases, group 2 those HFCs/HFOs and group 3 HCs.
Depending on the gas to be detected, the specific device that detects that category of gas needs to be purchased, and
then the specific gas selected via app or Modbus.
The table in the next chapter shows the list of gases detected and the corresponding group.
For example, if needing to detect R-410A, the required device needs to be purchased, described as “Group 1”. At the
time of installation, then, select R-410A via app or by setting the corresponding Modbus register.
6.1.2
Electrochemical sensors
Electrochemical sensors measure the partial pressure of gases in atmospheric conditions. The monitored ambient air
diffuses through a membrane into a liquid electrolyte inside the sensor. Immersed in the electrolyte are a measuring
electrode, a counter electrode and a reference electrode. An electronic circuit with a potentiometer supplies a constant
voltage between the measuring electrode and the reference electrode. The voltage, the electrolyte and the material
used to make the electrodes are selected according to the gas being measured, so that this is correctly transformed
electrochemically on the electrode for measurement and thus a current is generated that flows through the sensor. The
current value is proportional to the concentration of gas. At the same time, oxygen from the ambient air reacts with the
counter electrode. At an electronics level, the current signal is amplified, digitised and corrected based on other control
parameters (e.g. ambient temperature).
6.1.3
Pre-calibrated sensors and devices
Pre-calibrated sensors and devices are supplied with the calibration certificate included in the packaging, in addition to
the instruction sheet.
IMPORTANT:
This product uses semiconductors that may be damaged by electrostatic discharges (ESD).
When handling printed circuit boards, observe proper ESD precautions so as to not damage the electronics.