Problems existing in metrological verification of electronic scales

With the increasing load of transport vehicles, the maximum weighing and table size of electronic truck scale have also changed greatly. Take Huaibei Mining (Group) Company as an example. Before 1997, most coal sales scales were 30t lever mechanical scales, and the table size was 3m× 12m. After 2000, in order to meet the changing requirements of transport vehicles, the coal sales scale was gradually updated to SCS- 100 electronic truck scale, with the maximum weighing of 100t and the table size of 3.5m× 21m.. Individual units proposed that the weighing 100t could not meet the measurement requirements, and requested to purchase electronic truck scales weighing 150t ~ 200t. In view of the above situation, the verification regulation of digital indicating scale approved by 1997 has the following problems in the actual operation of verification work. Here, an electronic truck scale of 100t is taken as an example to illustrate: (1) the condition of fourth-class weight 100t that meets the requirements of laws and regulations.

It can be seen from the specified requirements of weighing test, repeatability test and discrimination test that all three tests need to test the maximum weighing. At present, the status quo of the verification department is that the county-level and even municipal-level verification departments only have 20kg fourth-class standard weights, and the total amount is only about 5t ~ 10t. Using these weights to verify the 100t weighing instrument is obviously far from the 100t weight required by the regulations. In recent years, the verification departments of some provincial cities have purchased weighing vehicles. According to the information currently available, the largest weighing vehicle only has a standard weight of 30t, which is far from meeting the requirements of the Regulation.

(2) Transport capacity

100t standard weight needs 10 10t trucks for transportation. Even if the verification department has 100t standard weight, it does not have such a huge transportation capacity. In addition, the safety of weight transportation is also a problem that cannot be ignored. In the transportation of tonnage weight, a special positioning frame should be set in the carriage, otherwise it will be easy to shift during transportation, causing the vehicle to overturn under unbalanced load.

(3) Eccentric load test: According to the requirements of regulations, the test weight of each supporting point is 14t, and 8 supporting points need to be loaded and unloaded by about 224t. Five test points are required, and weights are loaded and unloaded at the test points of minimum weighing, 500e, 2000e, 50% maximum weighing and maximum weighing respectively (e is the calibration index value). According to the calibration index value e=20kg, the total weight to be loaded and unloaded is about 400t.

The total amount of loading and unloading weights needed in unbalanced load and weighing test is about 624t t, what is the concept of this figure? Such a huge workload cannot be completed by any verification department.

The workload calculated here is only to successfully complete the verification workload of a truck scale. In the actual verification process, this situation is rare, and the verification process often needs to be adjusted and repeated due to reasons such as foundation, limit, grounding, shielding and system connection. The required human resources can be imagined.

The problems mentioned above are the requirements of the first verification in the regulations, and a lot of verification work in the measurement department is the follow-up verification. The following verification specified in the Regulations only means that the maximum weighing in the weighing test can be reduced to 2/3 of the maximum weighing, and the above problems still exist.

Related to the above problems, there is also a standard weight substitution problem. The regulations stipulate that the repeatability error is not more than 0.3e and 0.2e, and the standard weight can be reduced to 35% and 20% of the maximum weighing. The repeatability error is determined by applying the maximum weighing value of about 50% to the carrier three times. The problem here is obvious:

First, in order to determine the repeatability error, it is necessary to load and unload 300 tons of weights on the vehicle, and the workload is by no means ordinary.

Secondly, the repeatability error is 0.3e, so it needs to be replaced twice. The repeatability error is 0.2e, and it needs to be replaced four times. It is not practical to organize so many body double at the verification site.

Thirdly, it takes more manpower and material resources to verify large-scale weighing instruments by substitution method than directly using standard weights, and the operation feasibility is worse.

Verifying the relationship between cost and income has already talked about the huge cost of human resources. In addition, according to the requirements, there are standard equipment purchase fees, verification fees, transportation fees, vehicle surcharges, crossing fees, fuel costs, etc. These expenses need not be calculated carefully. They must be a large sum. However, according to the national verification fee standard, the verification fee for non-automatic weighing instruments with a measuring range of 80t- 100t is 2,500 yuan/set. If the verification department conducts verification according to the specified requirements, there is no doubt that the relationship between costs and benefits will form a greater asymmetry, which is also a problem that needs to be faced. 1, the buoyancy in the air, the development of objects in the air is directly proportional to the buoyancy of air displacement. Error caused by the density difference of air at atmospheric pressure and temperature.

2. The electronic scale is set incorrectly.

The gust of wind in the air, even if it is small, will push the balance up or down.

4. The weight of floating dust in the air.

5. Dislocation of mechanical components due to thermal expansion or contraction.

6. The magnetic field acts on the iron component.

7, the influence of static electricity, such as after putting the electronic scale on the carpet.

8. Distance vibration or earthquake interference.