Operating temperature range  | -40°F to 158°F (-40° to 70°C)  | 
  
  
Non-operating temperature  | -40°F to 167°F (-40° to 75°C)  | 
  
  
Humidity tolerance  | 5% to 90% non-condensing  | 
  
  
Airflow  | The PA-220R firewall uses passive cooling and does not
contain fans.  | 
  
  
Maximum BTU/hr  | 55BTU/hr  | 
  
  
Acoustic noise  | Emits no sound  | 
  
  
Maximum operating altitude  | 10,000ft (3,048m)  |