Zinc whiskers viewed under an
electron microscope
Zinc whiskers have
been responsible for increased equipment and system failure in
data centres.
Zinc whiskers can form on the
underside of electroplated zinc raised floor tiles
and on the bare metal surfaces of the pedestals and
stringers.
Zinc whiskers are typically 2
microns in diameter and over time they can grow to several
millimetres in length. These whiskers can become airborne if
disturbed and dislodged. Even CRAC air flow is strong
enough to dislodge these particles. Once dislodged they
circulate throughout the data centre and get blown or sucked
into equipment possibly resulting in short circuits usually
within power supply.
One data centre extension into
raised floor space previously used as offices was an example
where zinc whiskers have grown without any type of disturbance
over many years. The moment the subfloor barrier was removed
multiple power supply's failed within the live data
centre.
One of the main factors in zinc
whiskers being identified now is due to the age of many data
centre facilities. Zinc whiskers are not known to
cause any threat to humans however this has not been
extensively researched to date.
There are 2 types of zinc plated
floor tiles. Electroplated zinc and hot dipped galvanised.
Only electroplated zinc floor tiles grow zinc whiskers. These
tiles are identified by their even dull grey
appearance.
Electroplated Zinc floor
tile
Zinc plating is also applied via
hot dipped galvanising, however these types of tiles typically
do not grow zinc whiskers. This surface is identified by
a bright mottled appearance.
Hot dipped galvanised floor
tile
If
you think you may have zinc whiskers, the first thing to do is
to halt any work within the data centre and more particularly
in the sub floor. Contact us to
complete a site inspection and if zinc whiskers are found, we
will assist to formulate a plan to minimise further
contamination of your data centre and equipment.
The best option is to
carefully and systematically remove, decontaminate and replace
with new raised floor tiles. However, this is a costly
capital expenditure and there may not be funds in the
budget to cover this option. The alternative is to perform a
thorough and complete top to bottom decontamination of
the data centre and equipment beginning with the
electroplated tiles and the entire subfloor area
concurrently. This process should only be undertaken by
professional decontamination staff. This option can
provide a year or two of planning time and allow for
funds to be budgeted for tile replacement as zinc whiskers
will over time grow back unless a regular maintenance and
monitoring program is implemented.
Air scrubber pre-filter after Zinc
whisker decontamination
Zinc whiskers also grow on the
chassis inside some equipment
