Gravity zone division in some countries Italy and Germany have stipulated the gravity zone in the national metrology regulations in 1994 and 1995, respectively. These regulations enable weighing instrument measurement and equipment manufacturers to directly use one, two or The average gravitational acceleration value of several gravitational zones correctly adjusts the scale. At the same time, Austria also made a corresponding division of gravity. Since the relative change in global gravity is relatively small, a sufficiently large gravity zone can be determined. When the height h is the same, the maximum change of the gravity acceleration value $ g (that is, the difference between the gravity of the poles and the equator) is about. At the same geographic latitude U, the gravity acceleration value decreases with the increase of the height h, and decreases every 1000m 2. Therefore, the gravity zone is mainly for those countries or regions with a large distance between north and south or uneven terrain. The European Organization for Legal Metrology established a unified gravity zone in 2000. The size and number of gravity zones depend on the maximum allowable error of the scale when moving in the gravity zone, that is, the maximum variation range of the gravity acceleration value of the gravity zone. Germany and Italy use the following formula to determine the range of gravitational acceleration in the gravity zone: where: $ g / g is the relative allowable change of the gravitational acceleration in the gravitational zone, e is the maximum allowable error of the weighing instrument concerned, n is the weighing instrument verification The number of division values ​​e (n = maximum range divided by the verification division value, e is usually equal to the digital resolution d). Since the provinces of Germany and Italy span a small latitude, they divide the gravity zone according to administrative boundaries. The European New Gravity Zone established by the European Legal Metrology Cooperation Organization is applicable to countries that have been established or not. The new gravity zone has nothing to do with politics and national boundaries. The basis for its establishment is: 1) An independent gravity zone is determined for the weighing instrument, which is only related to the physical influence factors U and h and the accuracy of the weighing instrument; 2) The reference gravity acceleration value g is calculated by the standard gravity calculation formula, which is Used as the basis for weighing instrument adjustment; 3) Use the same criterion to calculate the maximum relative allowable error of the gravity acceleration value in the gravity zone, that is, the criterion is three times stricter than that of the German and Italian standards, and the range of the gravity zone is better than that of the German and Italian The outgoing gravity zone is obviously smaller. The biggest feature of the temperature regulating valve is that it only needs an ordinary 220V power supply and uses the energy of the regulated medium to directly automatically regulate and control the temperature of steam, hot water, hot oil and gas. It can also be used to prevent overheating or heat exchange. The valve has the advantages of simple structure, convenient operation, wide temperature regulation range, fast response time and reliable sealing performance, It can be adjusted at will during operation, so it is widely used in hot water supply in chemical industry, petroleum, food, light textile, hotels and restaurants. Temperature Regulating Valve,New Needle Valve,Marine Butterfly Valve,Valve Pressure Gauge Taizhou Jiabo Instrument Technology Co., Ltd. , https://www.taizhoujbcbyq.com