HVAC Recovery Test

Dear All,

Which instrument do you use for conducting Recovery test? and what is the source of particulate generator?


Room Recovery Test HVAC System

An HVAC stop test was performed in which the HVAC was turned off for one hour. Data was recorded before, during, and after the event. Environmental data (temperature, humidity, and differential pressure) was recorded and is presented along with particles. Particles were only measured in the Room

Shutdown of the HVAC started at approximately 8:20 AM and ended at approximately 9:20AM. Particle counts of size 0.5µm started to increase in number immediately after the HVAC was turned off, but did not go out of specification during the 1 hour event. The room specification for 0.5 µm particles in the grade C room is 350,000 particles/m3. The particle counter was set to report particles/m3. It was taking a 1 minute long count every 2 minutes. It was sampling 1 cubic meter of air in each counting period. Particle counts started to decrease about 2 minutes after the restart of the HVAC system.

The highest particle count observed was 138909 at 9:24AM, about 4 minutes after restarting the HVAC. Subsequently, and within 10 minutes after restart, the particle counts had settled to less than a few hundred counts/min.

On review of the other environmental data (temperature, humidity, and differential pressure) it was found that temperature and dP occasionally went above or below specification. In all cases, it recovered within 5 minutes of the HVAC being turned on.

AHU data (screen shots) from the computer are supplied by personnel for before, during and after the stop event.