The presence of both the particulate and gaseous contaminants have the following consequences:
- Airborne chemicals become dissolved in AC system condensate forming acids which can attack heat transfer surfaces.
- The gaseous contaminants can corrode the delicate electronic circuitry of the computers and printers.
- Airborne particulate collects on computer equipment and can affect performance of disk drives and tape equipment.
- Smaller airborne particulate pass through filters on air conditioners/AHUs and foul heat transfer surfaces, reducing efficiency.
- The presence of respirable particulate (less than 1 micron) and gas phase chemicals create an uncomfortable and unhealthy environment, causing health problems for employees.
TYPICAL AIRBORNE PARTICLE SIZE DISTRIBUTION IN AN EDP FACILITY
|Particle Size (microns)||Distribution|
TYPICAL GASEOUS CONTAMINANT LEVELS IN AN EDP FACILITY
|Ammonia||1.4 - 16|
|Nitrogen dioxide||0.002 0.003|
|VOCs (as Toluene)||0.1 0.2|
AIR PURIFICATION METHODS FOR EDP FACILITIES
The optimum filtration system for electronic data processing facilities will address as many of the potentially offending materials as possible – gaseous and particulate. The recommended system would consist of:
- a 30% ASHRAE rated pre-filter – for removal of higher size particulate matter.
- a bed of plain activated carbon media – for removal of general VOCs like toluene, xylene etc., other higher molecular weight hydrocarbons, chlorine.
- a bed of acid impregnated activated carbon media – for removal of ammonia.
- a bed of potassium permanganate impregnated activated alumina media – for removal of ozone, oxides of nitrogen, traces of chlorine, formaldehyde and other low molecular weight gaseous compounds.
- a 90-95% ASHRAE rated final filter – for removal of dust generated from the media as well as the sub-micron particulate matter generated in the EDP environment.
For controlling gaseous contaminants generated from within the EDP room
Provide stand-alone powered re-circulation air scrubbers, of the above configuration designed for at least 6 air treatment cycles per hour, inside the room.