... dry transfromer... Use:ZJ vacuum pumping unit is used to vacuum-pump of the electrical vacuum device in transformer substation, administration of ... limit vacuum degree is 5Pa. But it is are unsuitable for pumping toxic gas, explosive gas, high-oxygen content gas, high- ... metal.Feature:(1) Quick starting, high pumping rate, stable performance, easy-handling.(2) The unit takes Roots Pump as main pump ...