Hitachi AJ-CE series Operation Manual page 3

For More Precise Measurements
To be able to conduct more precise measurements, it is necessary to minimize the factors that contribute to
measurement errors. There are a great variety of such error-inducting factors, which can be linked to
machine error and performance of the balance itself, as well as the properties and condition of samples being
measured, and the measuring environment (e.g., vibration, temperature/humidity). These factors can readily
affect the results of measurement on a balance that has resolution comparable to that of the AJ Series.
This material includes some precautionary notes that the user should bear in mind to eliminate error factors
and ensure accurate measurement results.
Measuring Room
Balance
Maintenance
Calibration
Temperature
Vibration/Shaking
Gravity
Humidity
Drafts
Electromagnetic Waves
Static Electricity
Temperature
Absorption/ Vibration/
Evaporation Shaking
of Moisture
Magnetism Magnetisi
Measurement Errors
Static Electricity
Measuring Bench
Factor Analysis Chart for Measurement Errors
1. Precautions on the Measuring Room
1.1 Temperature/
Humidity
1.2 Vibration/
Shaking
1.3 Drafts
1.4 Gravity
1.5 Electromagnetic
Waves
Try to maintain constant room temperature as much as possible to prevent dew
condensation and unstable indications due to fluctuations in temperature.
Low relative humidity tends to induce static electricity. (Relative humidity of
about 60% is considered ideal.)
The measuring room should preferably be located on the ground floor or in the
basement. Higher floors are more susceptible to heavy vibration and shaking,
which make such locations less suitable for measurement. A room facing a
railway or road with heavy traffic should also be avoided as much as practicable.
Avoid choosing a location subject to a direct draft of airflow from an air-
conditioning unit or exposed to direct sunlight, which may cause abrupt
fluctuations in temperature.
Also avoid a room subject to a heavy flow of people, since fluctuations in drafts
and temperature are likely to occur in such a location.
The gravity acting on a sample varies depending on the latitude or height of the
location where measurement is being conducted. For this reason, the same
sample may show different weight indications from one place to another.
Therefore, make it a rule to calibrate the balance every time it is relocated.
When the balance is located near an object that generates intense
electromagnetic waves, it may be hindered from showing accurate weight due to
the effects of such waves. Therefore, avoid placing the balance in such a
location.
Precautions on the Measuring Bench
2.1 Vibration/
Shaking
2.2 Magnetism/
Static Electricity
If the balance is subjected to vibration during measurement, its indications will
become unstable, thus preventing accurate measurement from being conducted.
To avoid this situation, select a solid measuring bench that is less susceptible to
vibration. (A bench in a vibration-proof structure or one made of concrete or
stonework will be suitable.) Moreover, do not conduct measurement with a soft
cloth or paper placed under the balance, since the balance may be rocked out of
its precise level positioning.
Place the measuring bench in a location free from vibration as much as possible.
It is a good idea to install the measuring bench in a corner of the measuring room,
where less vibration is likely to occur than in the center of the room.
Avoid operating the balance on a bench that is susceptible to the effects of
magnetism or static electricity.