What is the temperature drift phenomenon? How can the influence of temperature drift on the measurement be avoided?
In the use of electronic strain-type electronic balances, you may encounter a phenomenon of temperature drift, that is, due to temperature changes, the balance of the balance when the initial load and the value after a period of time are inconsistent. There are many reasons for the temperature drift phenomenon, such as changes in the temperature and humidity of the use environment, the length of the warm-up time, the sensitivity of the internal sensors and electrical components of the balance to temperature and humidity (ie, temperature drift coefficient), and so on. The higher the balance accuracy, the more obvious this phenomenon.
In response to this phenomenon, our company made the following experiments:
Experiment 1: The effect of warm-up time on the balance display value.
JY2002 (200g / 0.01g) type electronic balance, with a temperature of 16 ℃ and a constant temperature device, is loaded with 200g F2 standard weight. indoors
Turn on after storing for 2 hours:
Time Indication (g) Data processing (g)
9:00 199.96 /
9:05 200.02 +0.06
9:15 200.06 +0.10
9:35 200.07 +0.11
At this time uninstall, it shows 0.10g.
It changes 0.06g in the first 5 minutes, 0.04g in the next 10 minutes, from 9:15 to 9:35, and 0.01g in 20 minutes. It can be proved that with the increase of the warm-up time, the balance's value gradually stabilizes; it also proves that although the value at the time of initial loading is inconsistent with the value after a period of time, as long as the value before unloading is subtracted After unloading the indication, an accurate reading of the load can still be obtained.
Experiment 2: The effect of temperature difference on the balance display value.
The test tool is the same as above. The balance is moved from the outdoor to the indoor, the outdoor temperature is 2 ℃, the indoor temperature is 18 ℃, the humidity is 63% RH, that is, the temperature difference is 16 ℃, there is a constant temperature device. Turn on immediately, the measured data are as follows:
Time Indication (g) Data processing (g)
14:25 200.00 /
14:28 200.44 +0.44
Uninstall at this time, showing 0.45g +0.45
Do not peel and reload
15:30 200.70 +0.70
15:59 200.76 +0.76
Uninstall at this time, it shows 0.76g +0.76
Load after zeroing
16:00 200.00 0.00
16:20 200.00 0.00
Immediately after the balance was moved from outdoor to indoor, due to the large temperature difference, the balance display value changed greatly. It changed to 0.44g in the first 3 minutes, 0.70g after 65 minutes, or 0.26g in the next 62 minutes, from 15: From 30 to 15:59, it changed to 0.06g in almost half an hour. This proves:
1. The greater the temperature difference, the greater the change in the balance display value. With the passage of time, the internal temperature gradually approaches room temperature, and the balance display value also tends to be stable.
2. Although the indication value changes due to the influence of temperature difference, the sensitivity of the balance has not changed. That is, when the temperature difference is large, the indication value at the initial loading and the indication value at the initial loading when the temperature difference is small are almost unchanged.
3. Indication before unloading-Indication after unloading = Indication value at initial load.
The balance should be used under conditions where the ambient temperature is relatively stable (temperature change is not greater than 5 ° C per hour). However, users may need to use the air conditioner just after starting it, direct sunlight, moving the balance from outdoor to indoor, indoor to outdoor and other various temperature differences:
1. At this time, the balance can reduce the measurement error by using the following methods.
2. Prolong the warm-up time as much as possible. The greater the temperature difference, the longer the warm-up time should be, generally 30 minutes to 2 hours.
3. Use standard weights to calibrate before use. The JY series electronic balance calibration weights produced by our company should be above M1 level.
4. It should be read at a fixed time after loading. For example, all the readings are displayed in 5 seconds after loading or the readings are displayed in units.
5. Multiple measurements, take the average value (3 ~ 5 times
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