mainly used for mine hydraulic support, oil field development, suitable for engineering construction, lifting and transportation, metallurgy forging, mining equipment, ships, injection molding machinery, agricultural machinery, various machine tools and various industrial departments In the mechanized and automated hydraulic system, petroleum-based (such as mineral oil, soluble oil, hydraulic oil, fuel oil, lubricating oil) and water-based liquid (such as emulsion, oil-water emulsion, etc.) with a certain pressure (higher pressure) and temperature are transported Water), etc. and liquid transmission, the highest working pressure can reach 70-120Mpa.