Labconco XPert Filtered Balance Stations 3962622 - Manual (Page 8)

Chapter 2: Prerequisites
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
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 balance should be calibrated and verified at least annually; for best
results, the balance should be calibrated inside the enclosure while running at
the desired face velocity.
Temperature Variation Requirements
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.
Humidity and Static Electricity Requirements
Electrostatics can be troublesome in a balance enclosure. It is important to
understand and, to the extent possible, control static charges. An electrostatic
charged vessel, sample or enclosure can apply forces and lead to errors in
weighing. The repulsion or attraction can be detected with micro, semi micro and
analytical balances. Static charges can also lead to particulates being attracted to
surfaces within the balance enclosure. Containment of harmful powders,
prevention of cross-contamination and clean-up is enhanced when static attraction
of powders is minimized. The construction of the XPert Filtered Balance System
and XPert Filtered Balance Station avoid the use of plastics, which are highly
insulative. The advantages to the glass and epoxy-coated metal construction are
twofold:
1. The enclosure does not contribute high electrostatic forces affecting the
precision of the balance.
2. The attraction and ultimate accumulation of powders, (hazardous or
nuisance), are minimized on the inside of the enclosure.