Hazardous Area Classification; Protection Approaches - Mettler Toledo Division 2 IND570 Serie Guia De Instalacion

1.1.

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
TOLEDO DOES
either not present during normal operating conditions or is present only for very short periods of
NOT CLASSIFY
time.
HAZARDOUS
AREAS!
A hazardous (explosive) area is classified as a Zone 22 area when an explosive 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 authorized agent of the customer.
1.2.

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, SICSpro load cells and discrete I/O in Division 2
locations, a non-sparking method for the IDNet and SICSpro circuits in Zone 2/22 locations, and an
intrinsically safe level "c" approval method for the analog load cell and discrete I/O in Zone 2/22
areas. Non-incendive means the power present is insufficient to ignite an explosive atmosphere
under normal operation conditions. Non-incendive for Division 2 areas is equivalent to intrinsically
safe level "c" in Zone 2/22 areas. 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 IND570xx 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 CEC, Section 18, Appendix F. If installed in other countries, refer to the electrical
regulations for the country of installation for specific wiring requirements.
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, SICSpro interface and DIO connections of the
IND570xx terminal is given. These parameters may include voltage, current, capacitance and
inductance values. A comparison of these values between the IND570xx terminal and the values for
other approved apparatuses (such as load cells for the analog load cell port) provides the ability to
use the IND570xx terminal with METTLER TOLEDO or any appropriately approved equipment. This
process is explained in the next chapter.
If a signal cannot be classified as non-incendive, non-sparking or intrinsically safe level "c", follow
the electrical regulations for the country of installation for specific wiring requirements of incendive
equipment in a Division 2 or Zone 2/22 area.
1-2 METTLER TOLEDO IND570xx Division 2 and Zone 22 Installation Manual 30205321 | 02 | 05/2017