IEC 60079-26:2021 pdf free download – Explosive atmospheres
5.2.2Basic requirements
The following basic requirements apply for separation elements:
a) a separation element shall provide a boundary between different areas or parts of the equipment complying with different EPLs to avoid a migration of flammable gasses, vapoursor dusts from parts of the equipment with higher EPL into parts of the equipment with lowerEPL;
b) if a potential ignition source becomes active in the part of the equipment with the lower EPL,it shall not act as an ignition source in the part of the equipment with the higher EPL, forexample the permissible surface temperature of the separation element shall not beexceeded; and
c) if an ignition can occur in the part of the equipment with the lower EPL, flame propagation into the part with the higher EPL shall be avoided.This consideration is not applicable toEPL Db or Dc enclosures with dust exclusion according to lP 5X.
5.2.3Mechanical partition walls
Partition walls shall be constructed of either:
a) corrosion-resistant metal, glass or ceramic;
b) other materials which can be verified as providing the same level of safety. In this case, the certificate number shall include the “x” suffix in accordance with the marking requirementsof lEC 60079-0, the certificate shall include the Specific Conditions of Use and the materialshall be specified in the instructions according to Clause 9.
lf the partition wall is under constant vibrational stress (for example vibrating membranes), theminimum endurance limit at maximum amplitude shall be defined in the instructions (seeClause 9).
For mechanical loads (for example pressure， static forces，torques) the applicable safetyrequirements of the relevant industrial standards shall be applied. Due to the maximumallowable specified process pressure, loads or temperature, the separation element shall notimpair the Type of Protection.
For glass or ceramic partitions，a minimum thickness of 10 % of the diameter/maximumdimension is required, with a minimum thickness of 1 mm.
A partition wall of other than metal, glass or ceramic shall be subjected to thermal endurancetests according to lEC 60079-0 before the lP testing.
Partition walls used in equipment mounted in the boundary wall of Zone 20 or Zone 21containments shall be dust-tight according to lP6X for the specified process conditions (forexample process pressure). When the surrounding area is classified as either Zone 1 or Zone 2,the partition shall additionally meet the enclosure requirements of lEC 60079-31 to ensure ahybrid mixture is not formed within the equipment. Partition walls separating EPL DalGb(Table A.7) shall comply with the type test for enclosures EPL Da.Partition walls separatingEPL Db/Gb (Table A.8)shall comply with the type test for enclosures EPL Db.