Identifying Common Particulates

 

Particulate contamination can have one or more of the following characteristics:

  • Abrasiveness - abrasive particulate may contribute to wear as well as fretting and fretting corrosion.
  • Hygroscopic - many particulate contamination compositions have an affinity for water and readily absorb water vapor in the air. If sufficient water vapor is available, the particulate can become wet with water at temperatures above the bulk room dew point.
  • Corrosive Composition - the elemental composition of a particulate contamination may be corrosive to materials within the computer system.

 

We will identify the common types of particulates that contaminate the environment and offer some suggestions for reducing and controlling contamination in your facility.

Synthetic Fibrous Particulate:

Common sources: Clothing

Other sources: Carpet fibers, Insulated drop in ceiling tiles

Because synthetics have a low melting point, they may create a sticky surface to which other particulates will adhere.

 

Metallic Particulate: Metal dust enters the data center environment from a variety of sources. Common culprits include worn air conditioning parts, new raised floors, rotor brushes in vacuum cleaner monitors and printer component wear. Another common culprit is the electrician, who might be hardwiring and leave metal debris behind. Metallic particulates conduct electricity. Because they conduct electricity, they have an increased potential for creating short circuits. They are also magnetically attracted to circuits because of the magnetic fields generated by computer equipment. This particulate usually shows up as rust.

 

Carbonaceous particulate: Carbon comes from automobile exhaust, tobacco smoke, printer toners and carbon paper dust. In addition to being conductive, carbon dust is also combustible.

This type of particulate can be disastrous as metallic particulates because humidity transforms the fibers into electrically conductive elements which also act as carriers of other particulates.

 

Fibrous Organic Particulates: These are natural based fibers such as cotton and wool. These fibers usually originate from clothing, but also from incorrect cleaning materials or packaging materials. These fibers absorb moisture and cause major problems with electronic circuits. Once a short circuit has been caused it is almost impossible to detect the cause of failure because this particulate disintegrates from the heat of the short.

 

Paper Dust: Paper dust and particulates can cause problems similar to the fibrous particulates. These particulates are attracted to magnetic fields.

 

Construction Particulates: These particulates originate from the improper sealing of the concrete subfloor, the eventual erosion of the concrete, sand, plaster, sheetrock, brick and wax. Because these particulates are so fine, they fall in the raised floor plenum and become airborne. They may be ejected through perforated floor tiles into the atmosphere or into floor cooled computer hardware at speeds of 500 linear feet per minute. These particulates are extremely abrasive.

Excessive particulate contamination within computer equipment can contribute to several problems, including corrosion, wear, heat transfer and failure of electrical contacts.