Magnetic Circuit Design Based on Circumferential Excitation in Oil-Gas Pipeline Magnetic Flux Leakage Detection
In the oil-gas pipeline magnetic flux leakage (MFL) detection, the qualitative and quantitative analysis can be achieved. The circumferential excitation technology is an effective way to detect or size axial direction of defects reliably; Magnetic circuit design has become the key part of this technology to meet the magnetized requirements of circumferential excitation. This paper studies the magnetized section of MFL detector of the oil pipeline. With combination of analytical method and magnetic segmentation method, the Kirchhoff magnetic equation was established with MATLAB to design a magnetic circuit calculation model. Take f325´8 pipeline as an example, calculations are carried out to choose suitable geometry parameters and material properties for magnetic circuit design. And simulation by large-scale finite element software ANSYS is carried out to verify the correctness of magnetic circuit design. It has been testified in the results that the design of magnetic circuit has completely met the requirements of circumferential magnetization.
Detector Leakage Gas Lpg Based On Telegram Notification Using Wemos D1 and Mq-6 Sensor
Based on the test results of the National Standardization Agency (BSN), as much as 66% of the gas cylinders tested were found to be unfit for use was studied by zhang[1]. Along with the increasing use of LPG gas, the quality of gas cylinder products has decreased, and the need for supervision of gas cylinder products from the manufacturer, so it cannot cause danger was studied by dae[2]. Gas leaks most often come from the gap between the mouth of the tube and the regulator so that it can cause pollution to the polluted room. This is due to the seal that serves as a sealing gap between the gas cylinder valve and the regulator not working was studied by saeed[3]. This seal serves to close and isolate the gap between the regulator and the upper mouth of the gas cylinder so that gas leakage can be avoided, or it could also be caused by rat bites on the hose which can cause gas to leak. For this reason, a LPG gas leak detection device can be made remotely. Created a LPG gas leak detection system based on Wemos D1 microcontroller using telegram notification. The whole tool is divided into several parts which consist of mq-6 sensor, ESP8266-01S module, wemos d1 microcontroller, and buzzer. This tool works when the ESP8266-01S module searches for the nearest internet network and the mq-6 sensor detects lpg gas, from the ESP8266-01S module and mq-6 sensor then to the Wemos D1 microcontroller to process, from the Wemos D1 microcontroller then activates the buzzer as a warning alarm that then transfer data through the ESP8266-01S module to the website and give notification of a gas leak to the smartphone of the user of the device. The mq-6 sensor functions if the gas content value is above 80. The results show that the gas content value is more than 80 as detected lpg gas, because it has tested the system and when there is no lpg gas the gas content value is less than 80.
Hygroscopic Expansion of some Casting Investments
CREDIT is generally given to Taggart1 for introducing the cast gold inlay to the dental profession. Although he realized that gold shrinks when cooled from molten state to solid state of room temperature, the investment available to him did not supply sufficient compensation. In 1910, Van Horn2 published a paper dealing with a method by which he obtained the compensation by means of wax expansion. The next major research in connection with this problem was the work of Coleman3 at the National Bureau of Standards. He determined the gold shrinkage to be 1.25 per cent and presented a casting technic with compensation values of quantitative nature. The total compensation for the gold shrinkage was obtained by the combination of the setting and thermal expansion of the mold. This procedure is the general practice followed at the present time for compensation. There are some disadvantages to this method. Skinner has indicated the difficulty of obtaining smooth castings and the improper compensation for the casting shrinkage.4 It has been found by Hollenback5 and Scheu6a that castings made at a high temperature are rougher than those made at a low temperature (450° C.), depending upon the great difference in thermal expansion between plaster of Paris and silica, which causes a poor union of the fine particles. This may also result in friability and there may be some warpage due to the differential expansion. A method which provides sufficient compensation at a low mold temperature is the hygroscopic casting technic.b Wilson7 showed that certain plasters expand as much as 0.0044 inch to the inch by taking up moisture from the air. With this information at hand, Scheula, b tested some commercial investment to determine what results the addition of moisture would have. He found6b: (1) All of the casting investments that were tested expanded. (2) The thicker the mix, the greater the expansion. (3) A mix with hot water expanded more than one with cold water. (4) The time at which the mix is placed in the water is of great importance. It was found that if the mix is placed in the water early, it would not expand so much as when placed in a little later. It was also found that if the mix was placed in the water after a certain time, it could not expand to the maximal amount. (5) The temperature of the water in which the mix is placed is important, for two reasons; (a) the temperature of the water controls slightly the expansion of the investment, and (b) water at a temperature of 1000 F. slightly softens the wax pattern so that the fine margins are not marred while expansion is taking place. The mix should remain in the water at least 20 minutes to obtain the full expansion, after which time no further expansion is obtained.