Vaisala HMT360 - Manual (Page 4)

Safety Guide ______________________________________________________________________
2 ___________________________________________________________________ M210483EN-E
ENGLISH
HMT360 INSTALLATION IN HAZARDOUS LOCATIONS
Protected installation is mandatory in a hazardous environment
In hazardous environments, always connect the transmitters via galvanic isolators or Zener
barriers. A galvanic isolator or Zener barrier must also be used when the transmitter body is in
a safe area, but the probe is installed in a hazardous environment. Examples of protected
installations are provided on the next page. Also read the HMT360 User’s Guide before
starting the installation.
The transmitter does not include a galvanic isolator or a Zener barrier. They can be ordered as
optional accessories from Vaisala.
2-wire Connection
Connect the unpowered power supply wires to the connectors: Ch 1 (humidity) and Ch 2
(temperature). Both channels require an own power supply. As Ch 1 is a main output, the
transmitter does not operate if only Ch 2 is connected (Ch 2 is optoisolated from transmitter
electronics).
Mounting the Probe Cable in Gas Group IIC Spaces
The following instructions shall be followed to fulfil the specifications of the EN50284 for
nonconductive layer of the probe cable:
- Never mount or handle the probe cable when hazardous gases are present.
- For achieving a conductive shield, cover the probe cable with conductive material like
metal or conductive tape or mount the probe cable in a metal conduit.
- Assure that the conductive shield fulfils requirements of the standard EN 50284
(resistance less than 1 GΩ) and make sure that it can not come loose in any operation
situation.
NOTE During the installation work of the probes in gas group IIC areas (requiring
category I devices), it has to be guaranteed that even in fault cases sparks
generated by impacts or friction on the surface of the housing can never
occur.
EU Directive 94/9/EC (ATEX 100a)
This product is in conformity with the provisions of the EU directive 94/9/EC (ATEX 100a):
- Standards EN 50014 and EN 50020.
- Standard EN 50284 for group II, category 1 G devices (for use in hazardous locations).
- Marking EEx ia IIC T4: temperature range -40...+60 °C and pressure range 0,8...1,1 bar.