Most ATEX mistakes begin before any hardware is ordered. They happen when the classified process is simplified into a paperwork task instead of treated as an engineering decision that changes booth scope and integration cost.
Mistake 1: Treating zoning as a fixed label from the start
Zone decisions should come from real operating behavior, not from habit or copied project notes. A better starting point is theATEX zone classification page, where the logic begins with chemistry, airflow, and classified volume.
Mistake 2: Assuming existing booth airflow is "good enough"
Old booths are often judged by fan nameplate or past experience instead of current validated performance. That can hide the real reason a retrofit gets expensive: the booth never had the airflow baseline that the new classified process requires.
Mistake 3: Buying equipment before defining the safety boundary
Teams sometimes choose robots, sensors, or cabinets before they know which parts of the system fall inside the classified envelope. That creates rework later because the protection concept was not aligned to the actual booth layout.
In practice, ATEX classification should inform the scope ofpaint booth automation, not follow it after procurement.
Mistake 4: Underpricing retrofit disruption
A retrofit can look cheaper until ventilation changes, cabinet relocation, interlock updates, and downtime are priced honestly. If those items stay vague, the project usually drifts into delay and scope expansion.