Various measures, conversions and definitions used for hydrogen systems STP = standard temperature/pressure = 0°C (32°f) and 1 bar (≈1 atmosphere). Some references say STP is 25°C (77°f), reason unknown. NTP = normal temperature/pressure = 20°C (68°f) and 1 atm (atmosphere). Functionally, NTP is almost the same as STP, and … Continue reading →