Shanghai Automation Instrument No. 4 Factory was founded in 1951, specializing in the production of pressure gauges, diaphragm pressure gauges, diaphragm pressure gauges, bellows pressure gauges, precision pressure gauges, magnetic auxiliary contact pressure gauges, differential pressure gauges, pressure gauge correctors, and The Baiyun brand series pressure gauges produced by the factory are widely replaced by chemical, metallurgical, transportation, power station, light textile, food, scientific research and other industries. The products are known for their high precision, variety and quality. Reputation and exports to Europe, America and Southeast Asia. Transforming emerging developments and applications, the unit is committed to the development of new products while upgrading old products. There are more than 100 kinds of more than 100 varieties of special pressure gauges, pressure measuring instruments, pressure controllers, pressure controllers, general pressure gauges and special pressure gauges and computer control systems.