Standard Meters Cubic per hour (Sm3/hr) or Normal Meters Cubic per Hour (Nm3/hr) for variating of alternative definitions for the standard reference conditions of temperature and pressure.
Nm3/hr - Normal Meters Cubic per Hour is represented at the temperature
of 0ºC and atmospheric pressure 1,013.25 hPa
Sm3/hr - Standard Meters Cubic per hour is represent at a Temperature of
15,5ºC, 15,6ºC, 20ºC, 25ºC etc and atmospheric pressure 1,013.25 hPa.