Where the standard proves most useful is in its demand for a documented safety lifecycle. Many retrofit projects fail not due to technical errors, but due to missing verification artifacts. Part 6 of CEI 31-35 specifies:

It covers:

It is the legal basis for the "Explosion Protection Document" required by law in many jurisdictions.

CEI 31-35 PDF: A Comprehensive Guide to the Italian Standard for Industrial Automation

Know the Lower Explosive Limit (LEL), flash point, and relative density of the gases involved.

It provides an analytical method for classifying hazardous areas where flammable gases, vapors, or mists are present. It serves as a practical implementation guide for the broader European standard EN 60079-10-1