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Chapter 2: Prerequisites
At a minimum, the supporting structure usually consists of a base
cabinet and chemical-resistant work surface.
The ability for analytical balances to accommodate vibration varies
with type and brand. More advanced balances have improved
tolerance, however in the preparation of a balance enclosure site,
please consider the following:
• Avoid tubular stands or mobile benches that have the potential
of moving when touched.
• Work surfaces should be of a thick rigid material that remains
stable when buttons are pressed. An epoxy benchtop or
accessory work surface is a minimum requirement.
• A bench that is rigidly mounted to the floor or fixed to the
wall, but not both, may be appropriate.
• The corners of a building typically have less vibration than the
center.
• The bench with the balance enclosure should not contain any
vibration-producing equipment, such as shakers or pumps.
• Marble, granite or epoxy balance tables are generally
recommended by the manufacturers of analytical and
microbalances. (See the installation instructions in Chapter 3).
• Marble slabs with dampening pads placed within the enclosure
are also an effective low cost means of controlling vibration.
The extent the balance readings are influenced by temperature
variations is a function of the balance design. Most manufacturers
would suggest that a temperature drift of 1-2°C is generally
tolerable. Only validation through your Operational Qualification
protocol can define what is acceptable. To minimize the potential
for temperature variations:
• Never install balances near heating sources such as radiators
and hot plates.
• Do not place the balance and enclosure on a bench that would
receive direct sunlight.