Hazardous Area Classification; Protection Approaches - Mettler Toledo IND560 Serie Guia De Instalacion

IND560xx Terminal Division 2 and Zone 2/22 Installation Manual

Hazardous Area Classification

A hazardous (explosive) area is classified as a Division 2 area when the hazard is
either not present during normal operating conditions or is present only for very
short periods of time.
METTLER A hazardous (explosive) area is classified as a Zone 2 area when an explosive
gas-air mixture is either not present during normal operating conditions or is
TOLEDO DOES
present only for very short periods of time.
NOT CLASSIFY
HAZARDOUS
A hazardous (explosive) area is classified as a Zone 22 area when an explosive
AREAS!
atmosphere, in the form of a cloud of combustible dust in the air, is either not
present during normal operating conditions or is present only for very short periods
of time.
The area must be classified by an agent of the customer.

Protection Approaches

Various protection methods are used by different manufacturers for equipment
located within Division 2 or Zone 2 or Zone 22 classified areas. METTLER TOLEDO
uses a non-incendive limited-energy approval method for the analog load cell and
a non-sparking method for the IDNet circuits. Non-incendive means the power
present is insufficient to ignite an explosive atmosphere under normal operation
conditions. Non-sparking means that the product does not have the ability to arc or
spark during normal operating conditions. Component and surface temperatures of
the terminal are also evaluated for these approvals.
Other inputs and outputs to the IND560xx terminal have been classified as
incendive, which means they could be capable of igniting such an atmosphere.
Whether an input or output is defined as incendive, non-sparking or non-incendive, it
must be protected accordingly. For installation in the United States, refer to the
current version of the National Electrical Code (NFPA 70, Articles 500 – 505) and
ANSI/ISA-RP12.6 for specific requirements. For installation in Canada, refer to the
current version of CSA standard C22-1, Section 18, Appendix F. If installed in other
countries, refer to the electrical regulations for the country of installation for specific
wiring requirements.
As a general guide, if a signal is rated as non-incendive and is connected to
another device that is non-incendive, and the non-incendive field circuit wiring
(NIFW) parameters agree in the correct manner, no special protection of the signal
is required. On the control drawings and certificates found in this manual, a list of
field circuit parameters for the analog load cell connection of the IND560xx
terminal is given. These parameters include voltage, current, capacitance and
inductance values. A comparison of these values from the IND560xx terminal with
the values for other approved apparatuses (such as load cells for the analog load
cell port) provides the ability to use the IND560xx terminal with METTLER TOLEDO
load cells and other manufacturers' load cells in an approved system. This process
is explained in the next chapter.
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