Dell Precision 7920 Owner's Manual page 130

Table 40. Gaseous contamination specifications
Gaseous contamination
Copper coupon corrosion rate
Silver coupon corrosion rate
Maximum corrosive contaminant levels measured at ≤50% relative humidity.
NOTE:
130 BIOS and UEFI
Specifications
<300 Å/month per Class G1 as defined by ANSI/ISA71.04-2013.
<200 Å/month as defined by ANSI/ISA71.04-2013.