欧美性做爰大片免费看办公室_69堂亚洲国产日韩精品无码专区成人妻中文字幕一区二区三区在线久久久久_成色P31S是国精产品吗

WLW Vertical oil-free vacuum pump Oil-free (corrosion-resistant) vertical reciprocating vacuum pump is a replacement product of W-type horizontal vacuum pump, which is the main equipment for obtaining rough vacuum. The complete isolation of the crankcase and the cylinder is achieved by the use of a fully sealed device; the piston ring is self-lubricating and achieves oil-free lubrication. Because there is no sewage discharge, this type of vacuum pump is especially suitable for vacuum distillation, vacuum evaporation, vacuum drying, vacuum concentration, vacuum impregnation and other processes in the chemical, pharmaceutical and food industries.