As early as in the Qin Shihuang period, the postal regulations were established and a postage network centered on Xianyang was established. The Han Dynasty inherited this system, and unifiedly called the name, specifying a ten-mile pavilion and a thirty-year milestone. The post office in the Tang Dynasty was greatly The development of the country has a total of 1600 Luzi and Minamata. On March 20, 1896, Emperor Guangxu formally approved the establishment of the Daqing Post Office. The State Post Office of the People's Republic of China is the beginning of the Chinese postal history with the emperor's squat in 1896. With the acceleration of the global economic integration process, logistics plays an increasingly important role in the market economy. Today we will explain to you the common postal vehicles. Why the postal car is green Everyone must be very curious how the postal cars they see on the road are green. In fact, green is a safe color in the world. In China's colors, green symbolizes peace, youth, prosperity and prosperity. So the postal car uses green. Since the founding of the People’s Republic of China, at the first national postal meeting, it was decided to use green as a special sign for the postal service. Thanks to this provision, China's postal offices, postboxes, and mailman's clothes, as well as postal parcels and postal vehicles are all green. The special colors of postal classes in countries around the world are based on the traditions and customs of the country. If Britain uses red, the United States uses gray. Corresponding vehicle body colors and “China Post†were sprayed on Chinese postal company vehicles as required. What are the privileges of the postal car? The first is the unlimited line, as long as the procedures for the passage of freight vehicles can enter the restricted area of ​​urban traffic. If a postal car is engaged in city collection and delivery service in urban areas and it is really necessary to park in a no-parking area, it can be temporarily parked without affecting the safety and smoothness of traffic. If road traffic accidents need to be dealt with by the public security traffic police, when it is necessary to investigate and collect evidence, when the vehicles need to be temporarily withheld, the traffic police department shall allow the drivers or their affiliated enterprises to promptly transship all express mail. After inspection and appraisal, the vehicles shall be promptly released. The postal car is a special vehicle dedicated to delivery The State stipulates that postal enterprises must not use vehicles with special postal signs to engage in business activities other than mail delivery, nor can they allow other units or individuals to use vehicles with special postal signs for rental purposes. In recent years, there have been numerous cases in which the use of postal special-purpose vehicles has been used. Some of the infringers have enjoyed the convenience of transporting special postal vehicles, and some have impersonated postal workers to use fraudulent means to collect business. However, as long as the postal sign vehicle information database is called out, it will be able to identify true and false. In the case of fraudulent use of the name of postal enterprises or special postal marks, or forging of special postal products or reselling of forged special postal products, forged special postal products and illegal proceeds may be confiscated, and a fine of 10,000 yuan up to 50,000 yuan shall be imposed concurrently. Check Valve is usually used for stopping back flow of medium. Check Valve Check Valve,Brass Check Valve,Spring Check Valve,Water Check Valve Ningbo Jiekelong Precision Manufacturing Co., Ltd. , http://www.jklvalve.com
The maximum permissible leakage of the check valve with non-metal elastic seals is zero, and that of the check valve with meal seals is 0.1xDNmm3/s. Therefore, QC passed valves with metal seals possibly have slight leakage. Hence, in the applications where check valves must not have any leakage, non-return valves with soft seals should be used.
Nominal pressure of Brass Check Valve is 1.6MPa and medium temperature for metal seal is -20℃~150℃, and medium temperature for non-metal seal is -20℃~100℃. When the non-return valve is used for saturated steam, the pressure of the saturated steam should be≤0.6MPa.