The Trade Metrology
Unit provides a range of calibration services centered around but
not restricted to the trading parameters of mass, length and volume.
These calibrations are directly traceable to the national
Measured Values for mass are usually quoted
on a weight - in - air basis, being the mass of a standard of
density 8g/cm3, which would balance the weight in air of density
The results can be given in any other basis
at the request of the customer.
The Unit maintains secondary standards for
length, which are calibrated periodically at CSIR and can therefore
offer calibrations of line standards with direct traceability to the
The unit also offers calibration of metal
content measures over the range of 1 to 20litres. The unit has the
capability to calibrate volumetrically by discharge of a transfer
liquid from a reference delivery vessel, ranging from small
laboratory glassware to 10litres.
All weighing or measuring instruments used
or intended for use in trade in Botswana must be verified before
they can be used. The Weights and Measures Act makes it an offence
for anybody who is found in possession of an instrument used for
trade that has not been verified.
Trade Metrology Unit caries out verification
of weighing and measuring instruments used in trade. This is done to
ensure that the instruments conform to their metrological
requirements (that it is suitable for use in the regulated area in
such a way that it is expected to provide reliable measurements) and
to the requirements of the Weights and Measures Act. The instruments
covered are as follows.
Weighing Instruments (these are divided into two classes)
Non - automatic.
An automatic instrument is an instrument
that weighs without the intervention of an operator and follows a
pre-determined programme of automatic processes characteristic of
the instrument. e.g. automatic fillers in a packaging
A non automatic instrument requires the
intervention of an operator during the weighing process, for example
to deposit on or remove from the receptor the load to be measured
and also to obtain the results, either displayed or printed. For
example an electronic counter scale or a weighbridge.
Measuring Instruments. e.g. tot measures, Bottle top pourers,
Bulk Flow meters
Measures of Length
Tape Measures ( steel,
Rigid, semi rigid, folding and mounted
The unit carries
out tests by sampling on the packer's premises or at traders
premises to check for the following;
The labeling of the product (that it
conforms with the requirement of the Weights and Measures
The accuracy and suitability of the
equipment and whether it was properly maintained
The adequacy of the quality control
system, and that it was being followed.
The adequacy of the records, and their
accuracy by checking packages from the appropriate
The quantity in packages.
Compliance with recommended pack sizes.