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Liow
05-14-2006, 10:56 PM
Hi,I'm newbie here,
need some help from all bros here, Thank you very much.:)

Can anybody explain to me different between Nm3/h and m3/h ?
This is for air compressor capacity requirement and how about
convert to litre/min ?

Thank You.:)

Robert Fogt
05-15-2006, 04:34 AM
The N stands for Normal. It means it was measured at standard temperature and pressure.

Because the volume of gasses change with temperature or pressure, it is necessary to specify the temperature and pressure the flow rate was measured at.

Standard pressure is 1 atmosphere. Standard temperature varies between industries, usually 0 ºC or 20 ºC.

In the case of air compressors, I do not think it will matter much. Just use m³/hr instead of Nm³/hr. You can convert to liter/minute on the flow rate conversion page.

Unregistered
07-31-2006, 01:31 AM
Hi
can you please give me the mathematical relation between Nm3/mn and Sm3/mn for compressed
thanks
my email is
cghediri@yahoo.com

Robert Fogt
07-31-2006, 10:33 AM
N is metric normal temperature and pressure
S is standard temperature and pressure

I do not know if they differ at all. The standard temperature and pressure differs between industries, and it may be that Normal and Standard use the same temperature for your industry. Standard temperature is usually either 0ºC or 20ºC, and standard pressure is usually 1 atmosphere.

If standard and normal do use different temperatures, then the relationship would be according to the ideal gas law. PV = nRT

Unregistered
02-09-2007, 02:21 AM
The difference between Nm3/h and m3/h for compressor is very important because the first one correspond to standard conditions (1 bar and 20°C), where the density of the air is 1.2060 kg/m3. m3/h usually correspond to the flow at pressure conditions (7 bar and 60°C), where the density of the air is 8.3934 kg/m3.

As the characteristics of the compressor correspond to standard conditions, you have to take care that X flow at pressure conditions correspond to Y flow at normal conditions. It means:
Y (m3/s) = X (m/s)*(8.3934/1.2060) = X*6.9597.

regards

Carlos Fuenzalida
(Chile)

Vacuum Engineer
12-13-2007, 02:03 AM
Nm3/hr - Normal Metres Cubed per Hour
This is at a Temp of 0 deg C and 1013mbarA

Sm3/hr - Standard Metres cubed per hour
This is an old throw back from SCFM and based on 60 Deg F and Atmospheric pressure..............i.e. 1013 mbarA and 15.6 Deg C

Am3/hr - Actual Metres cubed per hour
As it says "Actual" at the temperature and pressure conditions stated.

To convert Nm3/hr to Sm3/hr it's a ratio of the absolute temperatures -
(The difference between 0 and 15.5 deg C)

10 Nm3/hr *(15.6+273)/ (0+273) = 10.57 Sm3/hr

Where -273 is absolute zero on the temperature scale.

To convert either of the above to Am3/hr or m3/hr (as normally written)
you need to convert both the temperature and pressure ratios

10 Nm3/hr ..... To Am3/hr at 20 deg C and +2 bar G (Two bar above atmospheric)

10 Nm3/hr *(20+273)/ (0+273)*(1013/1013+2000) = 3.6 Am3/hr

A way to think of the above is:
You heated the volume to start with to 20 degC .... It therefore it got bigger.....Then you squeezed it at a higher pressure...It shrank

Just remember to convert using the absolute Temperatures and Pressures and you can't go wrong :)

Unregistered
02-01-2008, 11:18 PM
Nm3/h is a mass unit.m3/h is a volume unit. With Nm3/h you will always be able to relate to a beginning ie 0C.

Unregistered
04-11-2008, 05:01 AM
What is the conversion factor between Nm3/h and KW/h

Unregistered
08-16-2008, 09:55 PM
I think that difference between Nm3/h and kW/h is another question. "N" in the initial question of this topic means "Normal" for "Normal conditions". But I guess in your question "N" means Newton.

To understand why your question has not the same meaning you can wonder about the meaning of the unit : here Nm3/h and m3/h are both to count the flow. (a certain volume by a certain time). But kW is a power and kW/h is a power consumption. A power consumption has generally not the same meaning than a flow.

The first thing you have to do to convert an unit into another is to mind in international unit.

SI base units[9] Name Symbol Quantity
metre m length
kilogram kg mass
second s time
ampere A electric current
kelvin K thermodynamic temperature
mole mol amount of substance
candela cd luminous intensity

Candela is less used, but the other are very important.
You can convert any unit to a certain relation binding these base units.
To do this, you have to use the physical relations.

In your question you have first to detect what is not base units and to v=convert them
Newton (N) is a quantity of strengh, so you know the base physical relation that P=mg (here m means mass!)
P is expressed in N, m in kilogram, g in m.s-2 (acceleration)
So you can convert N in kg.m/s2 base units

W is Watt, it is a power. A power is the work during a certain time and the work is strengh needed to act on a certain distance.
Work is logically expressed in N.m.
So W is equivalent to N.m/s
As seen previously N is equivalent to kg.m/s2
So W is equivalent to kg.m2/s3 in base units of international system

you know 1k= 1000
and 1h= 3600s

So kW/h <=> (1000/3600) * kg.m2/s4 (A)

Then you can convert the other unit :

Nm3/h <=> (1/3600) * kg.m4/s3 (B)

So you can see that (A) and (B) have not common base units. That means their is no relation to convert Nm3/h to kW/h in the classical physic.

If you have written a phycial equation where on term is express in (A) unit and the other in (B) unit, we call this unhomogeneous relation it says false in term of classical physic. You can understand intuitively that it is very hard here to convert /s into m2

Moreover, one thing very important : when you use the method of conversion I have given you, pay attention that the physic equations you use to convert are applicable in the case you are studying. For example if you are not in an inertial reference frame, the expression of weight would change.

If you have any question about these explanations : derbouc@yahoo.fr

Lionel

08-29-2008, 11:10 AM
Hi
can you please give me the mathematical relation between Nm3/mn and Sm3/mn for compressed
thanks
my email is
cghediri@yahoo.com

Dear friend,
Nm3/Min is "Volumetric flow at normal temperature & pressure conditions". Normal temperature & pressure differ for company to company. Most used values are 1atm for pressure and 15.5 C or 288.5K for temperature.
Sdm3/min is "Volumetric flow at standard temperature & pressure conditions"
Standard temperature pressure conditions are standard valve and used same all over the world. For temperaure= 0 C or 273K and for pressure = 1atm.

Why we use them instead of simple m3/min?

The simple answer is to make calculations easy. e.g. we are compressing 100 Nm3/min air from 1atm to 50 atm pressure then the volumetric flow through the compressor will remains same in Nm3/min as we have clearly defined its temp and pressure conditions for volume calculations.

Simple relations b/w Sm3/min and Nm3/min:

Use modified form of ideal gas equation as given below,

(P1V1)/(T1) = (P2V2)/(T2)

Here,

P1 = Pressure at normal conditions i.e. 1atm
T1 = Temperature at normal conditions i.e. 288.5K
V1 = volume at normal conditions in m3/min
P2 = Pressure at standard conditions i.e. 1atm
T2 = Temperature at standard conditions i.e. 273K
V2 = volume at Standard conditions in m3/min

OR

For more accurate calculations use following relations,

(P1V1)/(T1Z1) = (P2V2)/(T2Z2)

Here Z is compressibility factor at operating temperature and pressure conditions. Available in literature for most of gases at different temperature and pressures.

I hope it may resolve your most of issues regarding Standard and normal volumetric flows. If you have any quarry you may mail me at

Regards,

Process Engineer

Unregistered
01-27-2010, 10:36 PM
very simple:
If u want to convert from Nm3/hr to Sm3/hr: Multiply nm3/hr*1.091584.

If u want to convert from Sm3/hr to Nm3/hr: Multiply nm3/hr*0.9161.

regards

Syed Khaleelullah

Lampost22
01-28-2010, 03:52 AM
Hello,

can someone please check my problem?

I have a flow rate of 708.4 Nm³/hr of nitrogen at a temperature
of -39°C and a pressure of 0.48MPa(g). It's molecular weight is
defined as 28.01 kg/kmol and it's density as 8.418 kg/m³.

What I need is the calculation of 708.4 Nm³/hr into kg/hr.

My equation was: 708.4Nm³/h * 1/22.414 *28.01kg/kmol=885.26 kg/hr

Is that correct?

JohnS
01-28-2010, 04:16 AM
Hello,

can someone please check my problem?

I have a flow rate of 708.4 Nm³/hr of nitrogen at a temperature
of -39°C and a pressure of 0.48MPa(g). It's molecular weight is
defined as 28.01 kg/kmol and it's density as 8.418 kg/m³.

What I need is the calculation of 708.4 Nm³/hr into kg/hr.

My equation was: 708.4Nm³/h * 1/22.414 *28.01kg/kmol=885.26 kg/hr

Is that correct?

It is correct provided that the volume has already been "adjusted" to volume at normal conditions, 0 °C, 101.325 kPa.

If the volume were stated at measured (actual) temperature and pressure, the answer would be quite different. The density appears to be density at actual temperature and pressure.

Unregistered
02-07-2010, 10:43 PM
Please explain how did you get the density of 8.3934 kg/m3 at 7 bar and 60 deg C.

Regards,

Charlie

The difference between Nm3/h and m3/h for compressor is very important because the first one correspond to standard conditions (1 bar and 20°C), where the density of the air is 1.2060 kg/m3. m3/h usually correspond to the flow at pressure conditions (7 bar and 60°C), where the density of the air is 8.3934 kg/m3.

As the characteristics of the compressor correspond to standard conditions, you have to take care that X flow at pressure conditions correspond to Y flow at normal conditions. It means:
Y (m3/s) = X (m/s)*(8.3934/1.2060) = X*6.9597.

regards

Carlos Fuenzalida
(Chile)

Unregistered
02-07-2010, 11:18 PM
Dear Friends,

Total air consumption : 500 Nm3/h
Site condition : 40 deg C , 500 Meter elevation and 45 % RH
Compressed air pressure needed : 8 bar

What is the volume flow rate needed in terms of actual m3/H , Nm3/H , standard m3/H, FAD
of the air compressor?

Regards,

Charlie

Charlie
02-08-2010, 03:03 AM
Dear Friends,

Given :

Air consumption requirements : 300 Nm3/h at 1 bar and 20 deg C
Site condition : 50 deg C, 500 meter altitude, 45 % RH
Pressure needed : 8 Bar

What would be the air compressor capacity in terms of FAD, Nm3/h and actual m3/h?

Thank you.

Charlie

harish narayankar
03-16-2010, 01:58 AM
nano meter cubeper hr to be converted to meter cube per hour

VenilVENILKUMAR@GMAIL.COM
05-14-2010, 05:37 AM

Normal flow, Normal Cubic Meters per Hour, (Nm3/hr)
Normal Conditions are defined as: Tn = 20.0 ºC, (68 ºF) Pn = 1.01 bara, (14.72 psia)
Note: the definition of Normal conditions are consistent with the calibration of the CME.

Standard flow, Standard Cubic Feet per Minute, (SCFM)
Standard Conditions for the calculation of SCFM are defined as: Ts= 15.6 ºC, (61 ºF) Ps= 1.01 bara, (14.72 psia)
Note: the definition of Standard conditions are consistent with the calibration of the CME.

Standard flow, Standard Liters per Minute, (SLPM)
Standard Conditions for the calculation of SLPM are defined as: Tn= 0 ºC, (32 ºF) Pn= 1.01 bara, (14.72 psia)
Note: the definition of SLPM conditions are consistent with the calibration of the CME.

Standard flow, Standard Cubic Centimeters per Minute, (SCCM)
Standard Conditions for the calculation of SCCM are defined as: Tn= 0 ºC, (32 ºF) Pn= 1.01 bara, (14.72 psia)
Note: the definition of SCCM conditions are consistent with the calibration of the CME.

Conversion basis and Flow Concerversion Table shows the calculation basis for the flow rate conversions.

Flow calculations

Standard flow, SCFM
Ts = 61 deg F pV = mRT
Ps = 14.696 PSIA m = 0.07374 lbm per SCF
R = 55.12 (ft lbf)/(lbm deg R) 0.22603 SCFM per lbm
M = 28.0134 mol/mol 6.33176 SCFM per (lb mol)/hr
Gas = Nitrogen
Nm3/SCFM = 1.71928
SCFM/Nm3/hr = 0.58164

Normal flow, Nm3/hr
Tn = 20 deg C
Pn = 14.72 PSIA pV = mRT
Pn = 101490.8 Pa m = 1.16726 lbm per Nm3
R = 296.6 J/(kg deg K) 0.3886 Nm3/hr per lbm
M = 28.0134 10.88605 Nm3 per (lb mol)/hr
Gas = Nitrogen
Nm3/SLPM = 0.0644
SLPM/Nm3/hr = 15.5275

Standard flow, SLPM
Ts = 32 deg F pV = mRT
Ps = 14.72 PSIA m = 0.00276 lbm per SL
R = 55.12 (ft lbf)/(lbm deg R) 6.03401 SLPM per lbm
M = 28.0134 mol/mol 169.0333 SLPM per (lb mol)/hr
Gas = Nitrogen

Flow Rate Conversions Table
Nm3/hr SCFH SCFM SLPM SCCM
3000 104695 1745 46583 46582500
2000 69797 1163 31055 31055000
1500 52348 872 23291 23291250
1000 34898 582 15528 15527500
900 31409 523 13975 13974750
800 27919 465 12422
700 24429 407 10869
600 20939 349 9317
500 17449 291 7764
400 13959 233 6211
300 10470 174 4658
200 6980 116 3106
100 3490 58.2 1553
90 3141 52.3 1397
80 2792 46.5 1242
70 2443 40.7 1087
60 2094 34.9 932
50 1745 29.1 776
40 1396 23.3 621
30 1047 17.4 466
20 698 11.6 311
15 523 8.72 233
10 349 5.82 155
8 279 4.65 124
7 244 4.07 109
6 209 3.49 93.2
5 174 2.91 77.6
4 140 2.33 62.1
3 105 1.74 46.6
2 69.8 1.16 31.1
1 34.9 0.582 15.5

0 GUESS OTHERS ARE ZERO TOO

I GOT BORED ENTERING THIS TABLE, BUT GOES FURTHER TO FRACTIONS.

Unregistered
05-21-2010, 01:27 AM
I would like to correct some information

the volume measured and operating conditions can be converted to other reference conditions:

when we speak about m³ we generally refer to the ISO system. In this system the normal conditions are :
- 0°C = 273.15 K (Kelvin)

- 1.01325 bar or 101.325 kP (kilo Pascal)

the notation is generally Nm³ but its wrong because in the international vocabulary of metrology N is used for Newton. The right notation for normal m³ is m³(n)

for the standard condition in ISO the reference are

- 15 °C = 288.13 K

- 1.01325 bar or 101.325 kP

the notation is Sm³

the relation between standard and normal m³ (calcul from P1 V1 Z1 = P2 V2 Z2, with Z as the compressibility factor) is dus :

1 Sm³ = 1 m³(n) * 288.15/273.15 = 1 m³(n) * 1.054914882

Unregistered
05-25-2010, 03:35 AM
thabks for ur help
The N stands for Normal. It means it was measured at standard temperature and pressure.

Because the volume of gasses change with temperature or pressure, it is necessary to specify the temperature and pressure the flow rate was measured at.

Standard pressure is 1 atmosphere. Standard temperature varies between industries, usually 0 ºC or 20 ºC.

In the case of air compressors, I do not think it will matter much. Just use m³/hr instead of Nm³/hr. You can convert to liter/minute on the flow rate conversion page.

Unregistered
03-29-2011, 10:51 AM

m³ = Nm³ x (T + 273)/273 x 1.033/(P+1.033)

Nm³ = 273/(T + 273) x (P + 1.033)/1.033

Where:

T = temperature °C
P= pressure kg/cm²

Unregistered
04-15-2011, 09:22 AM
pls, correct if I am wrong
50 nm3/hr (Pressure:6kg/cm2 & Temp:50 degree C) = 8.689 m3/hr
Thank you

khurram
05-22-2011, 10:18 AM
as per my understandings, for air compressors or gases being handled in dry conditions i.e moisture free, use nmc/hr else wise use m3/hr

Unregistered
05-26-2011, 09:54 AM
Nm3/s is the measure of energy or torque, this is very uncommon unit of torque. It stands for Newton metre cube per second

Unregistered
07-14-2011, 03:28 AM

The difference between Nm3/h and m3/h for compressor is very important because the first one correspond to standard conditions (1 bar and 20°C), where the density of the air is 1.2060 kg/m3. m3/h usually correspond to the flow at pressure conditions (7 bar and 60°C), where the density of the air is 8.3934 kg/m3.

As the characteristics of the compressor correspond to standard conditions, you have to take care that X flow at pressure conditions correspond to Y flow at normal conditions. It means:
Y (m3/s) = X (m/s)*(8.3934/1.2060) = X*6.9597.

regards

Carlos Fuenzalida
(Chile)

Unregistered
02-14-2012, 07:36 PM
Nm3/h is a mass unit.m3/h is a volume unit. With Nm3/h you will always be able to relate to a beginning ie 0C.

Don't think that Nm3/h is a mass flow unit. It is still a volumetric flow unit, but under specified conditions of pressure & temp.

Unregistered
03-04-2012, 06:29 PM
Re: Different between Nm3/h = m3/h ?

m³ = Nm³ x (T + 273)/273 x 1.033/(P+1.033)

Nm³ = 273/(T + 273) x (P + 1.033)/1.033

Where:

T = temperature °C
P= pressure kg/cm²

is it application for liquid and gas medium?
something i use to calculated for liquid uncorrect

Unregistered
05-13-2012, 01:25 AM
Please assist in the formula to convert SO2 PPM to mg/dNm3.

Thanks very much.

Unregistered
07-08-2012, 05:25 AM
Hi frnds,

Can u pls give details explanation of these problem???
3315Nm3/hr equal to MMBtu/day

Pls pls it's very urgent

Unregistered
07-17-2012, 12:01 AM
What is the conversion factor between Nm3/h and m3/h[/QUOTE]

JohnS
07-17-2012, 02:10 AM
What is the conversion factor between Nm3/h and m3/h[/QUOTE]

It depends. m³/h generally refers to a measurement at actual temperature and pressure. The volume of a gas is a meaningless concept unles the temperature and pressure are clearly stated explicitly or by convention. Nm³/h is a convention. The volume, regardless of actual conditions, has been adjusted to what the gas would occupy at 0 °C, 101.325 kPa. Unless those ARE the conditions, it won't be the actual volume.

The adjustment is usually taken via the ideal gas law. Compressibility or a better equation of state may be used if the gas pressure/temperature/volume relationship departs significantly from the ideal gas law.

Unregistered
08-10-2012, 10:37 PM
Dear friends,
Plaese help me for calculate the unit Sm3/hr into m3/hr : as the biogas flow pressure is 1000 mmWC and temp. is 44 deg. C .

Unregistered
10-22-2013, 10:32 PM
Hi
can you please give me the mathematical relation between Nm3/mn and Sm3/mn for compressed
thanks
my email is
cghediri@yahoo.com

Basically these are same,but the difference between that nm3/hr is a 0 deg c( NTP condition) and m3/hr is (actual condition ) flow at actual gas temperature .

Unregistered
10-23-2013, 12:47 PM
Hello everyone,
in order to convert ppm to_ kg"emissions" /year we have to know the volumetric flow rate of gas right ?? that is the first step and then we have to convert the volumetric flow rate to mas emission rate ..so my question is this ..if i have the test for TSS or TDS how to find the mass flow rate ? cause it says in the low that you have to know the molecular wight of gas ???
is there a different way for conversion these substances and also .. if it was a ppm in water how to convert it for example :80 PPM _COD in water how to convert it to kg /min ??

any help from you will be appreciated ...

JohnS
10-23-2013, 02:19 PM
Hello everyone,
in order to convert ppm to_ kg"emissions" /year we have to know the volumetric flow rate of gas right ?? that is the first step and then we have to convert the volumetric flow rate to mas emission rate ..so my question is this ..if i have the test for TSS or TDS how to find the mass flow rate ? cause it says in the low that you have to know the molecular wight of gas ???
is there a different way for conversion these substances and also .. if it was a ppm in water how to convert it for example :80 PPM _COD in water how to convert it to kg /min ??

any help from you will be appreciated ...

ppm for gases is a molar ratio, so you have to know total exhaust flow in moles per unit of time.
If you know volumetric flow, temperature and pressure, you can calculate this, or if you know mass flow of exhaust and average molecular weight.

Then multiply by ppm value to get pollutant flow in moles per unit of time. Multiply by molar mass (ie the molecular weight of pollutant) for mass flow.

teresa
12-11-2013, 12:59 AM
Hi everyone,
can someone help me with the conversion Nm3/h to m3/h.
Nm3/h - 200
Pressure - 30mbar!

Thank you very much!

Unregistered
12-13-2013, 03:19 AM
Hi,I'm Jiban Karmakar here,
need some help from all bros here, Thank you very much.:)

Can anybody explain to me different between Nm3/h and m3/h ?
This is for Hydrogen capacity requirement and how about
convert to litre/min ?

Thank You.:)[/QUOTE]

Unregistered
01-28-2014, 03:36 AM
It is unbelievable how no one takes in account moisture in the air...
shame on all of you, just using the ideal gas law...

For a displacement compressor the volume flow is constant for the same speed (theoretically).
If I have at the inlet of the compressor 1 bar, 20°C, 30% RH, the compressor gives me for example 300L/s or 0.3 m3/s or...
If I have the same compressor at the same speed at 0.9 bar, 30°C, 60% RH, it would still give me 300L/s or 0.3 m3/s or... (in practice this will change very slightly because of different PR's, etc..).
This is why the ISO1217 works with FAD. This is the volume flow referenced to the inlet of the compressor !! (which makes sense)

In the industry people always like to work with:

Nm3/h which is a massflow !! (and is totally stupid to work with for compressors)
Nm3/h will change for every different inlet condition (while m3/h not).

So now the question how to go from m3/h to Nm3/h, it is the same as going to a massflow.
But please take in account the humidity and don't just use the ideal gas law for dry air...

Mflow = Vflow (referenced at inlet) * Density-inlet

and then you can calculate Nm3/hr based on this massflow