An electronic balance is an instrument capable of accurately measuring the mass of an object, and is widely used in fields such as research, pharmaceuticals, chemistry, and food.
During actual use, the measurement results of the balance are often affected by various factors, among which temperature and humidity are the most common and significant factors. Understanding the impact of temperature and humidity on the measurement values of high-precision balances is of great importance for ensuring the accuracy and reliability of the measurement results. Meaning.
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1.1 
The Mechanism of the Impact of Temperature and Humidity on High-Precision Balance Measurement
The Influence of Temperature
(1) Change in Air Density: Changes in temperature cause a change in air density. In high-precision balance measurements, the buoyancy force acting on an object is related to the air density. According to Archimedes' principle, the buoyant force acting on an object in the air is equal to the weight of the air it displaces. When the temperature rises, the air density decreases, and the buoyant force acting on the object decreases, causing the displayed mass value on the balance to be larger; conversely, when the temperature drops, the air density increases, and the buoyant force acting on the object increases, causing the displayed mass value on the balance to be smaller. For example: By combining formula calculation and actual measurement, under standard atmospheric pressure, when the temperature rises from 10 °C to 30 °C, the air density decreases from approximately 1.247 kg/m3 to approximately 1.165 kg/m3. For an object with a volume of 0.001 m3, the buoyant force at 10 °C is approximately 0.0122 N, and the displayed mass is approximately 1.24 kg. At 30 °C, the buoyant force is approximately 0.0114 N, and the displayed mass is approximately 1.25 kg, resulting in an increase in the displayed mass of approximately 0.01 kg.
(2) Performance Changes of Electronic Balance Electronic Components: Modern high-precision balances typically use electromagnetic force sensors to measure the mass of objects. Changes in temperature affect the performance of electromagnetic force sensors, such as changes in resistance and capacitance parameters, which lead to drift in the output signal and affect the accuracy of the measurement results. In the metrology calibration laboratory, high-precision electronic balances are used to precisely weigh minute mass differences. If the temperature fluctuates by 2 °C, the internal metal components of the balance expand due to heat, causing the sensitivity of the sensor to change. Previously capable of measuring mass changes at the microgram level, at this point, there is a reading deviation, resulting in inaccurate measurement results. For example: Testing a brand's high-precision electronic balance, when the temperature rises from 20 °C to 30 °C at a rate of 1 °C per hour, the drift rate of the sensor output signal is approximately 0.02 mV per hour, resulting in a measurement result deviation of approximately 0.03 g per hour.
(3) Drift Caused by Temperature Changes: Experimenters tested the JJ200 (200 g/0.01 g) type electronic balance. Moving this balance from outdoors (with a temperature of 2 °C) to indoors (with a temperature of 18 °C and humidity of 63% RH), they turned it on immediately. It was measured that immediately after the balance was moved from outdoors to indoors, due to the large temperature difference, the balance indication changed significantly within the first 3 minutes, changing by 0.44 g, and after 65 minutes, it changed by 0.70 g, that is, it changed by 0.26 g in the next 62 minutes, from 15:30 to 15:59, approximately half an hour, it changed by 0.06 g.
For another model, AB313 (310 g/0.001 g), a similar test was conducted. Moving it from an environment of 5 °C to an environment of 25 °C, the indication changed by 0.2 g in the first 5 minutes after turning it on, and by 0.45 g after 90 minutes.
1.2 
The Impact of Humidity
1.2.1 
Hygroscopic Effect: The surfaces of components of high-precision balances are prone to absorbing moisture from the air, especially in environments with high humidity. Inhale
Moisture can lead to an increase in the quality of components, thereby affecting the zero point and sensitivity of the balance. For example, the core of an electromagnetic force balance is a single sensor combined with a magnet coil and a circuit board to form a weighing system. When the environmental humidity significantly increases, the insulation paint around the magnet coil will absorb moisture and change its own weight, causing the zero point of the balance to drift. The strain gauge sensor is an aluminum alloy elastic body with a silicone seal on the strain gauge. The silicone has a strong moisture absorption property. Water seeps into the strain gauge beneath the silicone and gradually affects the glue performance, thereby affecting the weighing. For instance, in an environment with a relative humidity of 85%, after placing a set of weights (1 g to 500 g) for 24 hours, the total weight of the weights increases by approximately 0.05 g. For the magnet coil of the electromagnetic force balance, when the relative humidity increases from 50% to 85%, the coil weight increases by approximately 0.02 g, resulting in a zero point drift of about 0.03 g. 1.2.2
Corrosion effect: High humidity environments accelerate the corrosion of balance components. Metal components are prone to oxidation reactions in humid air, generating oxides, thereby changing the surface properties and quality of the components. Corrosion not only affects the appearance of the balance but also leads to a decrease in the accuracy of the components, affecting the accuracy of the measurement results. Installation of a constant temperature and humidity device: Install a constant temperature and humidity device in the high-precision balance usage environment, controlling the temperature at 20℃ ± 2℃ and the relative humidity within the range of 40% to 60%, to reduce the influence of temperature and humidity changes on the balance value.
3.1.2
Reasonable location selection: Choose a place far from heat sources, water sources, and well-ventilated areas to place the high-precision balance to avoid direct sunlight and air from air conditioning vents blowing onto the balance to ensure the stability of the balance usage environment.
3.2 Daily maintenance
3.2.1
Regular cleaning and calibration: Regularly clean the high-precision balance to remove dust and moisture from the surface of its components. At the same time, conduct verification or calibration of the balance according to the prescribed schedule to ensure its accuracy and reliability.
3.2.2
Weight maintenance: Store the weights in a dry and clean environment to prevent them from absorbing moisture and corroding. Regularly conduct verification or calibration and cleaning of the weights to ensure their quality and reliability.
3.3
3.3.1
Operation norms
Preheating: Before using the electronic balance, follow the instructions to preheat it to reach a stable working state. For example, for a high-precision balance, conduct a preheating experiment for 30 minutes before weighing, and the stability of the measurement results is improved by approximately 80% compared to not preheating, with the deviation reduced from ±0.05 g to ±0.01 g.
3.3.2
Avoid frequent door opening and closing: During the weighing process of the balance, try to avoid frequent opening and closing of the balance door to reduce the influence of external temperature and humidity on the internal environment of the balance. For example, when frequently opening and closing the door (once per minute) during the weighing process, the indication fluctuation of the balance is approximately ±0.03 g; reducing the frequency of opening and closing (once every 5 minutes), the indication fluctuation is reduced to ±0.01 g.
4 Conclusion
Temperature and humidity are important factors that affect the accuracy of the balance's measurement values. Warm
The changes in temperature will affect the measurement results of the balance through mechanisms such as changes in air density and performance of the electromagnetic force sensor; changes in humidity will also affect the measurement results of the balance through mechanisms such as the hygroscopic effect, corrosive action and influence on the electromagnetic force sensor. Through experimental research, we can visually observe the relationship between temperature and humidity changes and the measurement results of the balance. For
To enhance the accuracy and reliability of the balance measurement, we should adopt measures such as environmental control, regular maintenance and operation standards, to reduce the influence of temperature and humidity on the measurement value of the balance, and achieve the goal of accurate weighing.