ASHRAE TC 9.9 sets the environmental guidelines for data centres. Beyond temperature and humidity, it addresses contamination in two forms: particulate and gaseous. The second is often overlooked.
Particulate: back to ISO 14644-1
For particulate contamination, ASHRAE points to ISO 14644-1 Class 8. That sets the ceiling for airborne dust, the domain of filtration, sticky mats and periodic cleaning.
Gases: the creeping damage
Gaseous contamination, especially sulfur-bearing gases, attacks copper and silver on circuit boards. ASHRAE recommends keeping the level within the G1 severity class of ANSI/ISA-71.04: the lowest corrosivity.
The corrosion limits
In practice G1 means a corrosion rate below roughly 300 Å/month for copper and 200 Å/month for silver, measured with reactivity coupons. Above those values, the risk of hardware failure rises.
Why it ties back to cleaning
Particles and gases reinforce each other: dust layers hold moisture and corrosive species against components. A clean environment reduces both the particulate and the gas-related load.
Key takeaways
- TC 9.9 covers both particles and gases.
- Particulate target: ISO 14644-1 Class 8.
- Gas target: G1 severity per ANSI/ISA-71.04.
- Dust holds corrosive species against components.