... vacuum equipment, Leak DetectorZQJ-291 series helium mass spectrometer leak detector includes three kinds of model: 291, 291K, 291S. ZQJ- ... 291 helium mass spectrometer leak detector has the same vacuum system as that of ZQJ-230D ... of log scale, cycling detection, suction gun detection, life-end-point acoustic frequency, two stage password setup etc.The main specificationType ...