The air cleanliness class by particle concentration of air in a cleanroom or clean zone shall be defined in one or more of three occupancy states, viz. “as-built,” “at-rest” or “operational”
The common mistake here is, many cleanroom certifiers are not turning devices on during “at rest” condition. The idea behind this is to see the contamination load of devices while they are running. This doesn’t mean proper production conditions but just up and running!
𝘏𝘢𝘷𝘦 𝘵𝘩𝘪𝘴 𝘣𝘦𝘭𝘰𝘸 𝘵𝘢𝘣𝘭𝘦 𝘪𝘯 𝘺𝘰𝘶𝘳 𝘭𝘪𝘣𝘳𝘢𝘳𝘺 𝘢𝘴 𝘢 𝘳𝘦𝘧𝘦𝘳𝘦𝘯𝘤𝘦!