Non-Sparking Approval; Protection By Enclosure; Incendive Inputs And Outputs - Mettler Toledo Division 2 IND570 Serie Guia De Instalacion

2.3.

Non-sparking Approval

The IND570xx has been approved as a non-sparking device for Division 2 and Zone 2
environments. This permits the equipment to be physically located within a Division 2 or Zone 2
area. Certain scale connections have also been evaluated as non-sparking (nA) for the ATEX and
IECEx approvals. This permits connection of a matching type of load cell in Zone 2 areas when the
load cell also has a non-sparking approval. This includes analog load cells, the IDNet High
Precision bases (using the "T-Brick T4" cell) or the PBK9xx platforms (using the MPGI cell). Note
that the load cell in the platform must also have a non-sparking approval and the maximum supply
voltage listed on the certificate must not be exceeded by the IND570xx terminal.
2.4.

Protection by Enclosure

The IND570xx protection method for dust environments (Division 2 and Zone 22) is a sealed
enclosure suitable for the environment. The cFMus approval lists this as "S" indicating special
protection and the ATEX and IECEx approvals list this as "tc" which indicates protection by
enclosure for Zone 22 areas.
For the harsh enclosure, the terminal has been tested to IP65 sealing standards which exceed the
required IP rating for the approval. The front panel sealing of the panel enclosure was tested and
meets IP65 requirements as well.
The panel version must be installed into a Factory Mutual approved dust tight enclosure to meet
cFMus requirements and an ATEX/IECEx tc certified enclosure to meet ATEX/IECEx requirements.
2.5.

Incendive Inputs and Outputs

If a specific input or output is rated incendive, then special wiring precautions must be taken to
protect the wiring in the Division 2 or Zone 2/22 area. Refer to the electrical regulations for the
country of installation for specific wiring requirements. Note that the United States prefers installation
of conduit hubs and conduit to protect incendive signals. Other locations may require conduit,
special cables, or certified glands. Refer to the first part of this chapter for details.
All inputs and outputs to the IND570xx terminal not listed in the previous sections as non-incendive
must be treated as incendive.
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Note that there is no I or I
max
circuit will only use the amount of current required for normal operation – more current cannot
be "forced" into the receive circuit. In this case, there is no need to compare the I
as part of the NIFW calculations.
NOTE: While the IND570xx with IDNet interface has been given a non-sparking approval, at
this time no METTLER TOLEDO High Precision IDNet bases are approved for use within an area
rated as Division 2 or Zone 2/22 in the United States or Canada.
METTLER TOLEDO IND570xx Division 2 and Zone 22 Installation Manual
value listed for the RS-422 receive circuit. This is because the
i
or I values
max i
2-7