Operating Principle and Features: The series SYF roots vacuum pump is with overflow valve. The figure-of-eight rotors are counter-rotating at a continuous speed inside the pump housing for suction and exhaust of gas. Two rotors are supported by two bearings and synchronized by a gear, which assures these two rotors in sure relative positions. They are close to to each other and also to the housing without actual contacting, so lubrication is unnecessary in the functioning housing. The thoroughly balanced working components and high precision bevel wheels ensue the pump be operated stably and continuously beneath the condition of high-pressure difference. Dynamic seal element utilizes our patent technology and imported oil seals, the vibration quantity of shaft to the shaft seals is managed to less than 0.02mm. A gravity valve is set up involving the suction and exhaust part of the pump. The perform from the gravity valve is as follows, once the pressure big difference between the suction and exhaust component is over the excess weight of the valve, the valve opens immediately, which tends to make the stress big difference constantly retain in a fixed controllable value, the worth would be the allowable highest strain difference to ensure the pump operate commonly and to ensure that in reality, the roots vacuum pump with overflow valve is often a form of overload self-protective pump. Series SYF roots vacuum pump with overflow valve has considerably greater speed at fairly reduce inlet stress and it is possessed overload self-protective function. Because it can be a pump of dry clearance seal construction, if a certain pumping pace price 15 and an ultimate vacuum need to be obtained, it truly is necessary to provide a reduced inlet stress for reducing the back movement, as a result, a pump should be backed in use, roots vacuum pump needs to be started off soon right after its inlet pressure reaches a permissible value for economization. It truly is allow to select diverse varieties of pump because the backing pump for factual requirements, such as oil seal pump and liquid ring vacuum pump. When pumping the gasoline containing huge quantity of vapor, the liquid ring vacuum pump will be the excellent backing pump.