Technical problems in the installation of tax cont

Relevant technical problems in the installation of fuel dispenser tax control device

I. relevant problems before installation

1 About the type selection test

the tax control devices of 9 enterprises across the country have been officially approved by the State Administration of taxation. According to national regulations, tax control devices can only be used in these nine enterprises. However, due to the short time and rapid progress of this work, all enterprises launched their products in a relatively short time. Although they have passed the examination and test designated by the state, there are imperfections in both function and technology. After obtaining the license, enterprises are constantly updating and improving, which is a good thing, but from another point of view, their current products are no longer the original tested products. In addition, due to the different conditions of the oil market in each province, the different management requirements in each region, as well as the different geographical and climatic environments in each region, enterprises are also making various improvements in order to meet the requirements of the market and users. Moreover, in order to reduce costs, some enterprises may use different components for the products produced in batches and the components delivered to the national test prototype in the early stage. In addition, the prototypes originally sent were carefully made by senior researchers, while the products produced in batches were probably inferior to the prototypes because they were originally produced by ordinary staff only by adding test equipment on the aircraft. Therefore, all provinces should carry out some necessary tests when selecting models, such as high-temperature or low-temperature tests, function tests, measurement accuracy tests, etc. of course, some tests are also regrettably based on the test data or results of provinces that have done experiments

2. As for low (high) temperature resistance

according to the JJF "technical specification for fuel dispenser tax control device", the working environment temperature of the tax control device is -25 ℃ to 40 ℃. At that time, the temperature was set in this range because it could meet the environment of most parts of the country, and the national assessment was also carried out according to this standard. At that time, it was stipulated that if the installation beyond this scope was omitted, it should be assessed according to the actual local conditions. This will not only inconvenience the cost of tax control devices nationwide, but also meet the needs of all regions. But the problem is that the later "assessment", the assessment unit designated by the state has been unable to control and carry out, and can only be mastered by the provinces according to their own requirements. For example, in several regions of our province, the minimum temperature in winter is lower than -40 ℃, and the time exceeding -30 ℃ should also be maintained for more than a month. Therefore, we conducted field tests at a temperature of about 30 ℃ (-25 ℃ to -35 ℃), and the results showed that the LCD display of the prototype did not display and the display lagged, and the electronic components also drifted at low temperature. It can be seen that such a test is necessary. For example, in the high-temperature areas in southern China, sometimes the temperature will be higher than 40 ℃, and it is best to do a high-temperature test

3. On the power on aging of products

due to the tight working time, enterprises produce when there is demand in order to reduce costs and reduce product backlog. Therefore, most of the products produced have not been electrified or aged enough, and the instrument will drift after being used for a period of time. Such products will cause the phenomenon that the tax amount and the measurement amount will not come together in the early stage after use, which is easy to cause unnecessary disputes and troubles. In addition, some defects of products or components can also be found through aging, which can be solved before installation, reducing the workload of installation or after-sales service. In the test, we found that some products drifted and unstable after one month retest, so it is suggested that all provinces should put forward aging requirements to users when using

II. Problems related to metrological verification

1 Before installation, such as the accuracy adjustment of the fuel dispenser

according to national regulations, the fuel dispenser should be verified to be qualified before installation, that is, the unqualified fuel dispenser should be adjusted. Theoretically, all fuel dispensers in use nationwide should be in a qualified state, because they are all within the verification cycle. But the actual situation is that many fuel dispensers are unqualified. The reasons are: (1) the original verification is not allowed; (2) The original verification was qualified, but later it naturally exceeded the tolerance; (3) The owner of the gas station did something on the fuel dispenser; (4) Originally, it was not verified because it was not commonly used

no matter what the reason is, it should be adjusted well. The test shows that for the adjustment of these fuel dispensers, we must make the pulse coefficient of the computer at the factory value, and then use the mechanical adjustment wire to adjust it. If it is qualified, it will be qualified, and if it is unqualified, we will take measures. We cannot adjust it by adjusting the pulse coefficient. Because the tax control devices of various enterprises are designed according to the pulse coefficient when leaving the factory, the adjustment range is not very large, and it is easy to fall behind the adjustment range of the fuel dispenser computer. Even if you keep up with it, after using it for a period of time, the small flow will soon be out of tolerance. In addition, the fuel dispenser replaced by the original computer fuel dispenser is actually installed on a gauge that is not qualified for the improvement of product performance, and the verification after installation is definitely unqualified. In this way, it is sometimes unclear whether it is originally unqualified or the influence of tax control devices

2. About the temperature measurement in the verification

according to the requirements of the verification regulation, the muzzle temperature and the oil temperature in the gauge should be measured during the verification. The influence of temperature measurement on the final result mainly includes two items, namely, the correction of volumetric expansion coefficient of the gauge and the correction of volumetric expansion coefficient of oil. In spring and autumn, that is, when it is close to 20 ℃, the correction of the volume expansion coefficient of metal gauges has less influence, and the correction of oil products has more influence. In winter and summer, these two factors have a great impact. Therefore, the temperature measurement must be accurate, especially the measurement of muzzle temperature is most likely to produce large errors. The verifier should determine when the temperature at the muzzle of the gun is most representative according to the specific situation of each gas station. According to our experience, it is generally better to read at about 50 liters, or simply put the first can out of use, and the assurance is greater

3. About small flow verification

according to jjg443-1998, the fuel dispenser should be verified at 20% of the maximum flow, which we call small flow verification. Up to now, this has still not attracted the attention of the national fuel dispenser verification personnel. It is understood that at present, the small flow in many provinces in the country has not been verified. Most of the installed or trial installed provinces have not carried out small flow verification. According to our experiments, it is necessary to carry out small flow verification. Because some of the fuel dispensers in use on site have been used for many years, and the small flow rate has been out of tolerance, but we didn't know it before. However, the performance of some new fuel dispensers with small flow is not very good, and the "flow error" curve under small flow is very steep. I have found many fuel dispensers with qualified large flow and unqualified small flow in the test

in addition, attention should also be paid to the adjustment of small flow, which must be very accurate, otherwise there will be trouble. We have done experiments. For example, the 0.2qmax flow rate of a fuel dispenser should be 5l/s. We verified it to be qualified at (4.7 ~ 4.8) seconds, but it was seriously out of tolerance at (5.2 ~ 5.3) seconds. From this point of view, in order to ensure that the fuel dispenser is in a qualified state for a long time, it is recommended that the flow point of small flow verification should be q ≤ 0.2qmax

according to the current situation, the fuel dispenser cannot adjust the small flow by itself, but can only rely on some additional devices

4. About quantitative verification

when the fuel dispenser tax control device is installed, in addition to the normal verification, quantitative verification should also be carried out. Because the treatment of the interference amount of the replaced computer is different from that of the original computer, especially for those tax control devices that maintain the original computer, quantitative verification is more necessary, because some tax control devices do not consider the interference amount at all. In order not to increase the workload, the first two times can be verified in the normal way, and the third time can be verified in the quantitative way. If there is no problem, it will be qualified, and if there is a problem, the test will be conducted again. If there is a problem, please ask the manufacturer to solve it

5. The verification time before installation is too long

according to the regulations, the verification before installation is only three times for large flow and three times for small flow, usually about an hour. However, the actual situation on site is much more complicated than expected. The reasons are: (1) the original fuel dispenser is unqualified and needs to be adjusted; (2) The small flow was not checked before, but now the small flow is out of tolerance; (3) Originally, it was adjusted by computer, but now it must be adjusted mechanically; (4) The performance of the fuel dispenser is unstable. Generally speaking, for an unqualified fuel dispenser, the verifier with a higher technical level can adjust it at most three times, but it is difficult to say when encountering a fuel dispenser with unstable performance. In the experiment, we encountered two new fuel dispensers produced by a certain factory at a certain station. After adjusting them for more than a dozen times, we couldn't adjust them. Finally, we didn't adjust them until we found that the fuel dispensers deteriorated by about 2% without adjusting them. Therefore, all provinces must consider the above factors when doing experiments, and take this workload into account. At the same time, when installing in a large area, experienced verifiers should be organized to concentrate on it

6. Accuracy adjustment during verification after installation

according to national regulations, the measurement accuracy of the tax control device that replaces the original computer is required to reach ± 0.3%. If the original computer is maintained, it should be no less than 1 word from the display of the original computer. However, some enterprises do not understand the documents thoroughly, and adjust those that do not replace the original computer by "± 0.3%. In this way, the tax accumulation and measurement accumulation are sorry. Practice has proved that it is difficult to adjust to" ± 1 "and be stable, and all provinces should pay attention to this problem

III. relevant problems in installation

1 Voltage does not adapt

the tax control devices of some enterprises cannot adapt to the voltage of all types of fuel dispensers, because even the same manufacturer and the same model of fuel dispensers have different voltages. For example, an enterprise originally considered a certain model when developing it, but it could not work normally after being installed on site. After more than a day of searching, it was found that the fuel dispenser also worked when the voltage was 1 or 2V, while the tax control device designed according to the standard 3V could not work

2. Current does not adapt

the tax control devices of some enterprises can not adapt to the current of all types of fuel dispensers. One enterprise has installed a certain type of fuel dispenser, but once encountered a situation that it did not work normally after installation. After multiple inspections. It is found that the current cannot meet the needs of the original machine after being shunted. This problem, like the voltage problem, occurs in the tax control device that saves the original computer type. These phenomena explain two problems: first, the circuit designed by enterprises should be more adaptable; Second, it should be noted that "even the products of the same manufacturer, the technical indicators are not necessarily the same ".

3. Grounding problem

because many fuel dispenser computers in the country were not produced by professional fuel dispenser manufacturers at the beginning, but developed by many different computer companies, various technical indicators are different, and the calculation methods and function settings are also different. And during installation, some are grounded separately, some are grounded together, and the connection with the background machine is also very irregular. For such gas stations, attention should be paid to common grounding during installation Or the interference caused by the connection mode. In the experiment, we have encountered the phenomenon that the tax controller and the original computer interfere with each other due to the common ground, resulting in the non counting of oil payment

reliable tensile and compression experiments

4 The installation time is too long

the test shows that the installation time also has a great impact on the whole installation work.