As per NFPA 69 ( http://hamyarenergy....A 69 - 2002.pdf) to purge H2 gas (100% pure) I need to maintain following range of N2 gas purity. Given that NFPA (& I failed to get any other document) doesn't describe dependency of temperature & pressure upon LOC (Limiting Oxidant Concentrations) ...how do I know that the range of N2 purity calculate will be adequate for my process conditions?