This brief describes the helium carrier-gas flow recommendations for the various pumping configurations available for the 5973N family of MSDs.
This document provides helium carrier-gas flow recommendations for the 5973N family of Mass Spectrometers (MSDs) to assist customers in selecting the appropriate pumping configuration. It compares diffusion-pumped systems versus turbomolecular pumps and distinguishes between standard and performance turbomolecular systems based on gas throughput and column requirements.
| Optimal helium gas flow (El) | 1 ml/min |
|---|---|
| Maximum recommended helium gas flow for El operation | 1.5 ml/min |
| Recommended column dimensions for El operation | 0.25 mm x 30m |
| Maximum recommended helium gas flow for CI operation | 1.2 ml/min |
| Copyright Year | 1999 |
Turbomolecular pumps are more rugged regarding vacuum integrity fluctuations and tolerate oxygen, water, and moderately reactive contaminants far better than diffusion pumps.
The performance turbomolecular pumping system is required for Electron-capture negative ion mass spectrometry (NCI) because buffer gas loads exceed those of reagent gas flows in PCI.
The sum of the reagent gas flow and helium carrier-gas flow should not exceed the maximum recommended helium-gas flow for EI operation cited in Table 1.