With the increase of automobile users and the expansion of the amount of oil used, in order to meet the needs of market supply and transportation, large-tonnage and large-volume oil tank trucks have emerged. For a long time, in the shipment and measurement of light oil products, the tank truck after verification is an important measuring instrument in oil product settlement and trade settlement. From the delivery of the upper-level oil depot to the verification of the intermediate tanker truck, and then to the inspection and acceptance of the lower-level gas station, in this series of processes, the petrochemical department is constantly strengthening the measurement management mode of the promotion of the sales of the lower-level gas station. Determining that the volume error of oil depot shipments is within +0.3%, and how to calculate the loss in tank truck transportation? The objective existence of these problems has made the measurement and verification of tank trucks more and more important.
First, the definition of the capacity comparison method
The capacity comparison method is the most widely used verification method in capacity measurement. At present, there are first-class standard metal gauges with high accuracy, so the capacity comparison method can be used not only for the verification of working gauges, but also for the verification of standard gauges at all levels. Its measurement process is as follows: fill the standard meter with water to a certain volume scale line, and after the liquid level is stably reading, pour all of it into the verified working meter. After the liquid level is stable, read the marking line capacity value of the working gauge. Compare and analyze the respective display values of the standard gauge and the working gauge, you can get the verification result. For example, how big is the error of the working gauge and whether it is qualified? If the working gauge has no graduation line, then its stable liquid level position is The capacity value of the standard gauge is at the scale position on the working gauge, which is the capacity value calibration.
The law has the following characteristics:
(1) Simple operation, rapid verification and high work efficiency;
(2) The environmental conditions are not high, and indoors at room temperature are sufficient;
(3) It has high verification accuracy.
Second, preparations before testing
Generally speaking, the detection environment of the capacity comparison method is fixed. There must be a high platform for placing standard metal gauges. There must be enough water source on the high platform. The testing field under the high platform must be solid and flat, so that the tanker can be parked steadily. . Therefore, some advance preparations must be made when checking the capacity of the tanker truck. Such as:
(1) Determine whether the high platform, water source and testing site of the testing station are complete and qualified;
(2) Park the oil tanker under a high platform, and prepare a water pipe between the standard metal gauge and the oil tanker;
(3) Connect the water outlet of the standard metal gauge with the prepared water pipe, the inlet of the water pipe is connected to the water outlet of the standard metal gauge, and the outlet of the water pipe is placed at the oil inlet of the tanker;
(4) Prepare the commonly used measuring tools, such as dipstick or T-square, thermometer, stopwatch, 1000ml graduated cylinder, steel ruler, tire pressure gauge and protective equipment.
Third, the measurement of basic data in testing
The large number of measurement tools used when verifying the tank truck capacity will inevitably generate a large amount of measurement data, so it is necessary to measure step by step and properly keep the quantity.
(1) Determine the position of the lower gauge point and measure the total height of the lower gauge point with a dipstick;
(2) Use a dipstick to detect the height of water in the oil tank and use a steel ruler to detect the outer height of the oil inlet;
(3) Use a thermometer to measure the storage water temperature and ambient temperature;
(4) Use a tire pressure gauge to measure the air pressure of each tire of the tanker;
(5) At the time of verification, use a stopwatch to calculate the titration time to wait after water is injected into the tanker;
(6) According to the nominal capacity of the tanker, calculate and record the 75% capacity value.
From the measurement of these overall basic data, a unified, specific and detailed application of the various capacities of the automobile tank truck is formed, and the basic data is completed in various aspects such as the calculation of external high values, water storage temperature, and capacity values, to provide further refinement. Thick technical data.
Fourth, the verification of the capacity value in the test
The verification of the capacity value is divided into two parts, one is the verification of the nominal capacity of 75% with the content value; the other is the verification of the content value in the range of 75% to 100% of the nominal capacity. When verifying 75% of the content value, it is necessary to select a standard metal meter to inject 75% of the nominal capacity of water into the tank truck according to its use requirements; when verifying within this nominal capacity, every time water is injected, It is necessary to read the water surface height and water temperature of the glass tube of the standard metal measure, and record it in detail for verification; when the water in the oil tank reaches 75% of the nominal capacity, wait for the water temperature and wall temperature in the oil tank to balance, then measure And record the water surface height and water temperature in the oil tank.
When the water level in the oil tank is stable, use a special T-square to measure the height of the liquid level. The height measurement should be carried out twice. When the difference between the two readings is greater than 1mm, the measurement should be repeated. The arithmetic average value is the height corresponding to the capacity of the point. If the tanker has dual oil inlets, the liquid level should be measured separately, and the average value of the measurement should be taken as the air height of the capacity at that point. The operating procedure is roughly the same when verifying the value in the range of 75% to 100%. No less than 10 verification points within the range of 75% to 100% of the nominal capacity of the oil tank with a nominal capacity of 10000L or less (including 10000L) shall not be less than 12 verification points with a nominal capacity of the oil tank above 10000L. Record the water temperature of the standard gauge and the tank truck for each measurement.
After the tank volume measurement is completed, the bottom-mounted pipeline can be measured. The pipeline volume measurement can be done by putting water in the pipe and then putting the water in the pipe into a measuring cylinder for measurement. Open the drain valve to drain the water, observe that the drain port is in a drip state, and close the valve after 3 minutes. The above is the first verification. For newly manufactured and repaired oil tanks, the capacity value verification shall be carried out no less than twice. The difference between the high value of the second-pass verification and the first-pass verification should not be greater than 1mm, otherwise the test should be repeated. The subsequent verification can be performed once. Generally speaking, after all data measurement is completed, strict data processing is required. At the same time, in order to understand the measured capacity data intuitively, piecewise linear interpolation can be used to compile a detailed capacity table.
The capacity verification of automobile tank trucks is a technical and comprehensive process. It needs to consider many factors. The rapid, efficient and accurate measurement of the capacity of automobile tank trucks is an important research topic. Handover, cost accounting, ensuring trade fairness, and energy measurement management are of great significance. Therefore, through the understanding of the definition of the capacity comparison method, some work preparations are made in the actual verification process, and the basic data and the approved capacity value are accurately measured. These are very important for the overall analysis of the capacity verification method of the automobile tank truck.