Hi
In general, for some the questions asked in the forum, we can get good answers in the internet itself
For ex STP and NTP, the def in net is as below
STP - Standard Temperature and Pressure
STP is commonly used to define standard conditions for temperature and pressure which is important for the measurements and documentation of chemical and physical processes:
- STP - Standard Temperature and Pressure - is defined by IUPAC (International Union of Pure and Applied Chemistry) as air at 0oC (273.15 K, 32 oF) and 1 atm (101.325 kN/m2, 101.325 kPa, 14.7 psia, 0 psig, 29.92 in Hg, 760 torr, 33.95 Ft.H2O, 407.2 In.W.G, 2116.8 Lbs./Sq.Ft.)
- STP - commonly used in the Imperial and USA system of units - as air at 60 oF (520 oR) and 14.696 psia (15.6oC, 1 atm)
NTP - Normal Temperature and Pressure
NTP is commonly used as a standard condition for testing and documentation of fan capacities
Coming back to the question asked, NM3 is used to have the common norms. If we use m3 /hr , then we have to know at what temperture it is? . To combine both, we are converting the actual volume in to the NTP usinf\g the formula
(P1 X V1)/ T1 = (P2 X V2 ) / T2
where P1 - Norma prssure and P2 - Actual pressure
regards
Vinayak