Effects of Contaminants

Destructive interactions between airborne particulate and electronic equipment can happen in many ways, some of which are outlined in the following subsections.

Physical Interference

Hard particles with a tensile strength at least 10 percent greater than the component material can remove material from the component surface by abrasive action or embedding. Soft particles might not damage the component surface, but can agglomerate (stick together) as the result of electrostatic charge build-up and cause clogging. If these particles are tacky, they can collect with other particulate matter.

Corrosive Failure

Component failures can occur from the corrosion of electrical contacts caused by certain types of particulate. Some particulates absorb water vapor and gaseous contaminants which adversely affect electrical components . Salts can grow in size by absorbing water vapor (nucleating). If the area is sufficiently moist, salts can grow large enough to physically interfere with a mechanism, or cause damage by forming corrosive salt solutions.

Short Circuits

The accumulation of certain types of particles on circuit boards and other components can create conductive pathways , thus creating short circuits. Many types of particulate are not inherently conductive, but can become conductive by absorbing moisture from the air. When this happens, the problems can range from intermittent malfunctions to component failures. To avoid this problem, care should be taken with both the proper filtration of air and careful control of humdification.

Thermal Failure

Thermal failures occur when cooling air cannot reach the components. Clogging of filtered devices can cause restricted airflow resulting in overheating of components. Heavy layers of accumulated dust on hardware components can form an insulative layer that can lead to heat- related failures. Regular replacement of air filters and cleaning of components will help to avoid this problem.

In one data center, plastic sheeting designed to contain particulate from a decommissioned server was actually causing thermal outages in an online server three feet away. The fans sucked the plastic just close enough to block inlets and overheat the system. Engineers couldn't find the problem because, when the system shut down, the fans stopped and the plastic dropped away. Plastic sheeting should be taped down to avoid this problem.