Laboratory Scale and Balance Operating Guide
Laboratory scales and balances are fundamental instruments for quantitative analysis. Proper use and maintenance ensure accurate and reliable mass measurements.
I. Types
- Analytical Balances: Readability of one-tenth milligram or better. Used for high-precision weighing in analytical chemistry and pharmaceutical applications.
- Precision Balances: Readability of one milligram to one gram. Used for general laboratory weighing where ultra-high precision is not required.
- Microbalances: Readability of one microgram. Used for weighing extremely small samples.
II. Operating Procedures
- Location: Place the balance on a stable, vibration-free surface away from drafts, direct sunlight, and temperature fluctuations.
- Leveling: Verify the balance is level using the built-in bubble level. Adjust the leveling feet until the bubble is centered.
- Warmup: Allow the balance to warm up for at least thirty minutes, preferably longer. Electronic balances should remain powered on continuously.
- Calibration: Perform internal calibration if available. Verify calibration with certified external weights.
- Weighing: Use appropriate weighing vessels. Tare the vessel before adding the sample. Close the draft shield doors during weighing. Record the reading after it stabilizes.
III. Maintenance
- Keep the balance and weighing chamber scrupulously clean
- Use a soft brush or lint-free cloth for cleaning. Never use compressed air inside the weighing chamber.
- Verify calibration daily with certified check weights
- Have the balance professionally serviced and calibrated annually
- Replace desiccant in the weighing chamber regularly if used
