nm3/hr to kg/hr - OnlineConversion Forums

I do not know why you want to do this, but the difference lies in the density of the air.

If you want to compare mass flow rates of the oil and the air, you must convert the volumetric flow rate of the air to a mass flow rate. First year engineering stuff.

The density of air at normal conditions is 1.204 kg/m³. Multiply the volumetric flow rate (Nm³/hr) by the normal air density (1.204 kg/m³), and you have your answer:

115 Nm³/hr x 1.204 kg/m³ = 138.46 kg/hr.

Could you be so kind as to tell us why such a simple calculation is so urgent that you could not do it yourself?

Perhaps it's due in tomorrow and "Sir" wont give an extension.

I hate homework questions as much as anyone. However, this did not seem as such.

In light of the question and my answer, kindly vote me a Good Answer!

No Sir, I can't give you GA, because it seem you answered in hurry and anger with OP and made it wrong. Density of air at NTP (at 0 deg C and 1 atm pressure) is 1.293 kg/Nm^3. So, the right answer is

115 Nm³/hr x 1.293 kg/m³ = 148.7 kg/hr.

It is a straight conversion, you do not need any pressure or temperature into consideration.

The calculation is:

115 Nm3/hr x 28.95 (MW of air) / 22.414 Nm3 = 148.5 kg/hr

Thanks alot for the reply.

You have cleared my confusion for the Temperature and pressure consideraations.

Science is in the details, good answer!

I agree that the symbols used can be confusing to those not familiar.

N is the common designation for "normal", which in this case stands for "standard temperature and pressure" or STP. Unfortunately, STP itself has various definitions.

MW stands for molecular weight, as any high school chemistry student can tell you.

Both of these symbols are very commonly used, and were used correctly in this case.

Saying that N "means" Newton is just as wrong as not defining N to begin with. Correcting Kg with kg is just being fussy.

I do agree that symbols should be defined, as they can mean many different things depending on the field, language and culture. However, in this case, the symbols used are very common when dealing with gases, and should be very familiar to anyone who could answer this question.

So the OP has asked a question using widely accepted symbols, which was clearly understood and has been answered. It probably is not important to him that you did not understand.

Multiply the volume flow rate ( m3/hr) by density( kg/m3) you will get mass flow rate.(kg/hr).

We shouldn't prolong the continuation of misinterpretation of the definitions of STP and NTP condition, and the value of density at each of the different conditions.

NTP, Normal Temperature and Pressure is air at 20oC (293.15 K and 1 atm (101.325 kN / m2, 101.325 kPa, 30 inches Hg, 760 torr)
NTP dry air has a density of 1.204 kg / m3.

STP, Standard Temperature and Pressure is air at 0oC (273.15 K, and 1 atm (101.325 kN / m2, 101.325 kPa, 30 inches Hg, 760 torr)
STP dry air has a density of 1.292 kg / m3.

Standard sea level atmospheric pressure = 101 325 Pa
Air density, Kg / m3 = [1.2929 X 273.13 X (AP - ( SVP x RH ) / ( T + 273.13)] X 760
Where:
T = oC
AP = Absolute Pressure, mm of Hg

SVP = Saturation Vapour Pressure of air over water at temp T

RH = Relative Humidity (decimal)

and Mikerho, a GA

Isn't RH expressed in %? Great disambiguation btw.

Ahh, it would be simple if this were true. I have never heard NTP used here in the states, but Nm^3 is common.

STP is "defined" here in many different ways different ways: STP