INFICON
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(WD) 724-250 450 650 -Low Voltage Operating Manual 220627.docx
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4.5 Remote sensors
LDMR series is a range of remote sensors designed for use with the LDM units.
Low voltage LDM250, LDM450, or LDM650 units include either 2, 4, or 6 LDMR remote sensors
for detecting HFCs, HCFCs, and mixtures and carbon dioxide (CO2).
Please Note!
The sensors used in the LDMR series have limited selectivity and are therefore
not gas specific. Care should be taken when installing the equipment to minimize
any cross contamination from other gases or vapours.
For further guidance on specific applications contact us.
5
Location/Installation
Correct location of the LDMR is essential to ensure optimum operation of the system. Special
consideration must be given to air movement and whether the gas to be detected is heavier or
lighter than air. For gases heavier than air (e.g. Refrigerants (HFC, HCFC) or CO2) the sensor
should ideally be located approximately 20cm above floor level. Connect the sensor according to
the wiring diagram.
NOTE! For unused channels a jumper (8) must be mounted and a >100 kohms resistor (attached)
must be installed between (+) and (S) to prevent open sensor alarms.
Otherwise, the channel will indicate a fault alarm.
When changing or replacing a LDMR a new calibration must be performed.
5.1
ALARM LEVELS / CHANGING ALARM LEVELS
The unit is normally supplied with default set alarm thresholds.
These must be verified or reset during commissioning.
To set or change the alarm thresholds you need a MCT150 Calibration tool and a small
screwdriver.
Full details regarding custom alarm set-points for a range of gases together with a detailed
procedure are outlined in specific data sheets. Multiple gases and alarm set-points can be
accommodated on a single LDM as each channel is totally independent.
5.2
Function Control
Testing the system is recommended to be done once a year. A basic function test can be
performed using MCT150. Extended control and calibration require test gas with a specific
concentration.
6
Technical Data
