Compliance · ASHRAE Technical Committee 9.9
ASHRAE TC 9.9: data center contamination and environmental guidelines
Indoor: data centers
ASHRAE Technical Committee 9.9 (Mission Critical Facilities, Data Centers, Technology Spaces and Electronic Equipment) publishes the environmental guidance data centers are designed and operated to. For contamination, it recommends keeping the white space at ISO Class 8 cleanliness under ISO 14644-1 (3,520,000 particles/m³ at ≥0.5 µm), holding corrosive gases within ANSI/ISA-71.04 severity level G1 (copper corrosion below 300 angstroms and silver below 200 angstroms per month), and keeping relative humidity below 60 % to protect circuit boards from corrosion.
Limit values
ASHRAE TC 9.9 Limit Values
Every value ASHRAE Technical Committee 9.9 publishes for the 2 parameters below, with its averaging period, as the standard states it.
Who it applies to
Who Uses It
Data center operators, colocation providers, and the equipment makers whose warranty conditions refer to the guidance, and designers of technology spaces. Particulate cleanliness is typically achieved with MERV 8 filtration for recirculating air and MERV 11 to MERV 13 for outside air.
Monitoring
How Monitoring Supports It
Particles, temperature, and humidity can be monitored continuously in the white space and at the air intakes. The data shows when a filtration problem, nearby construction, or a humidity excursion puts equipment at risk. Corrosion severity is measured separately, with copper and silver reactivity coupons or corrosion monitors, because it is not a concentration any gas sensor reports directly.
Recommended
best match-
Industrial monitor for indoor and outdoor sites. Built-in sensors cover the essentials, and hot-swappable gas sensor cartridges and a differential-pressure option add more.
Built-inRelative HumidityParticle Count (by size)Gas 1
Free: one more gas sensor cartridge
Gas 2
Free: one more gas sensor cartridge
MultiSense
Free: a MultiSense, stock or built to order
Expansion
Free: differential pressure
Also measures 11 more
Dew PointHeat IndexIlluminance / LightPM1PM10PM2.5Total PM / Mass Conc.Barometric PressureEquivalent Continuous Level (Leq)Sound Pressure Level (SPL)Air Temperature
Alternative
Aethair IAQ-
Aethair IAQ built-in sensors
Compact plug-in monitor with every sensor built in, nothing to add. Ideal for straightforward indoor air quality monitoring.
Built-inRelative HumidityParticle Count (by size)Also measures 11 more
Formaldehyde (CH₂O)Carbon Dioxide (CO₂)Dew PointHeat IndexPM1PM10PM2.5Total PM / Mass Conc.Barometric PressureAir TemperatureVOC (Total)
Who measures each parameter
| Parameter | Aethair PRO | Aethair IAQ |  External |
|---|---|---|---|
| Particle Count (by size) | Built in | Built in | 1 instrument via Thiamis |
| Relative Humidity | Built in | Built in | 12 instruments via Thiamis |
Devices
Devices That Cover ASHRAE TC 9.9
How much of this standard one Aethair monitor covers, followed by the third-party instruments in the sensor catalog that measure its parameters. Each connects to Environet through a Thiamis gateway, which adds whatever the monitor leaves out.
Aethair monitors
Covers both on its own
Covers part of it (combine on one Thiamis)
Article Library
Articles on ASHRAE TC 9.9
Data Center Air Quality Monitoring, Inside and Out
Data center air quality monitoring for operators: ISO 14644 cleanliness in the white space, construction dust, generator emissions, and perimeter noise.
Questions
ASHRAE TC 9.9 FAQ
What cleanliness does ASHRAE recommend for data centers?
ISO Class 8 under ISO 14644-1 for the white space, which is 3,520,000 particles per cubic meter at 0.5 µm and larger.
What humidity does ASHRAE TC 9.9 guidance call for?
Relative humidity below 60 %, to protect circuit boards from corrosion.
What is ISA-71.04 severity level G1?
The mildest corrosion class for gaseous contamination: copper corrosion below 300 angstroms per month and silver below 200 angstroms per month, measured with reactivity coupons or corrosion monitors.
Monitor Against ASHRAE TC 9.9
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