Welcome to OnlineConversion.com Forums

 OnlineConversion Forums converting normal litres/min to g/s
 [ Home ] [ Forum Home ] Register FAQ Calendar Search Today's Posts Mark Forums Read

 Convert and Calculate Post any conversion related questions and discussions here. If you're having trouble converting something, this is where you should post.* Guest Posting is allowed.

#1
11-17-2010, 10:41 AM
 Unregistered Guest Posts: n/a
converting normal litres/min to g/s

hi there,

so, ive been given a value of air flow in normal litres per minute, which i need to convert to grams/sec. i've never encountered 'normal litres' before so ive been madly googling and ended up here

i know the conditions under which the flow is taking place (high temp & pressure), and i've also been given reference normal conditions for the air density (kg/Nm^3) (where T= 273.15K and P = 1.01325bar)

my question: is the correct way to do this: convert the flow rate and density to the values they will actually have [ie. NL * (1.01325/actual pressure) * (actual temp/273.15) and Ndensity* (1.01325/actual pressure) * (actual temp/273.15)]. then convert the litres to m^3 and multiply by the density to get kg/min which is easy to convert to g/s?

or can i just say: normal litres -> convert to normal m^3 ->times normal density to get 'normal' mass flow ->then multiply by (1.01325/pressure)*(actual temp/273.15)

i get two different answers if i do this, and im not sure which one is right...i would guess the first one?
#2
11-17-2010, 12:46 PM
 JohnS Moderator Join Date: Dec 2007 Location: SE Michigan, USA Posts: 9,535 Rep Power: 19
Re: converting normal litres/min to g/s

Quote:
 Originally Posted by Unregistered hi there, so, ive been given a value of air flow in normal litres per minute, which i need to convert to grams/sec. i've never encountered 'normal litres' before so ive been madly googling and ended up here i know the conditions under which the flow is taking place (high temp & pressure), and i've also been given reference normal conditions for the air density (kg/Nm^3) (where T= 273.15K and P = 1.01325bar) my question: is the correct way to do this: convert the flow rate and density to the values they will actually have [ie. NL * (1.01325/actual pressure) * (actual temp/273.15) and Ndensity* (1.01325/actual pressure) * (actual temp/273.15)]. then convert the litres to m^3 and multiply by the density to get kg/min which is easy to convert to g/s? or can i just say: normal litres -> convert to normal m^3 ->times normal density to get 'normal' mass flow ->then multiply by (1.01325/pressure)*(actual temp/273.15) i get two different answers if i do this, and im not sure which one is right...i would guess the first one?
Normal liters ignore actual temperature and pressure and calculate the volume the gas would have at "normal" conditions, the ones you stated. At normal, the molar volume of any gas, at least approximated by the Ideal Gas Law is 22.414 L. The accepted average molecular weight (and molar mass) for air is 28.964 g/mol. Hence 22.414 L is 28.964 g.
#3
11-17-2010, 09:40 PM
 Unregistered Guest Posts: n/a
Re: converting normal litres/min to g/s

Quote:
 Originally Posted by JohnS Normal liters ignore actual temperature and pressure and calculate the volume the gas would have at "normal" conditions, the ones you stated. At normal, the molar volume of any gas, at least approximated by the Ideal Gas Law is 22.414 L. The accepted average molecular weight (and molar mass) for air is 28.964 g/mol. Hence 22.414 L is 28.964 g.
so, if im understanding you right, its even simpler - just say NL*molecular weight/molar volume?

this gives me...yet another different answer. *sigh* when did units get so complicated!

thanks for the help!
#4
11-18-2010, 03:34 AM
 JohnS Moderator Join Date: Dec 2007 Location: SE Michigan, USA Posts: 9,535 Rep Power: 19
Re: converting normal litres/min to g/s

Quote:
 Originally Posted by Unregistered so, if im understanding you right, its even simpler - just say NL*molecular weight/molar volume? this gives me...yet another different answer. *sigh* when did units get so complicated! thanks for the help!
If you know actual flow and actual density, you can just multiply

If you know normal flow and normal density, you can just multiply

A few cautions:
*Don't mix normal and actual
*In actuals, be sure you are using absolute pressure, not gauge (also absolute temperature)
*The molecular weight method I provided assumes dry air. The Handbook of Chemistry & Physics has some corrections for moist air if you know the moisture content. (Moist air is slightly lighter, because MW of water is 18).
#5
11-18-2010, 03:38 AM
 Unregistered Guest Posts: n/a
Re: converting normal litres/min to g/s

Quote:
 Originally Posted by JohnS If you know actual flow and actual density, you can just multiply If you know normal flow and normal density, you can just multiply A few cautions: *Don't mix normal and actual *In actuals, be sure you are using absolute pressure, not gauge (also absolute temperature) *The molecular weight method I provided assumes dry air. The Handbook of Chemistry & Physics has some corrections for moist air if you know the moisture content. (Moist air is slightly lighter, because MW of water is 18).
okay. as always, i was overthinking things...thanks!
#6
11-22-2010, 11:53 PM
 Unregistered Guest Posts: n/a
Re: converting normal litres/min to g/s

Hello.

I have similar problem. I have flow given in normal liters per minute, i must convert to velocity. but i must use the value for simulation, which will be at 600K and 3 bar pressure.

what is the correct approach?
#7
11-23-2010, 03:10 AM
 JohnS Moderator Join Date: Dec 2007 Location: SE Michigan, USA Posts: 9,535 Rep Power: 19
Re: converting normal litres/min to g/s

Quote:
 Originally Posted by Unregistered Hello. I have similar problem. I have flow given in normal liters per minute, i must convert to velocity. but i must use the value for simulation, which will be at 600K and 3 bar pressure. what is the correct approach?
"Normal" liters are measured at 273.15 K, 1.01325 bar, At your conditions, get actual flow as
normal liters/min x 1.01325 bar/3 bar x 600 K/273.15 K
(this assumes ideal gas law is good approximation and compressibility factor can be ignored)

Recognize that lier is also a cubic decimeter to convert to cubic volume flow. Divide by area to get average velocity.
#8
11-24-2010, 03:48 AM
 Unregistered Guest Posts: n/a
Re: converting normal litres/min to g/s

Quote:
 Originally Posted by JohnS "Normal" liters are measured at 273.15 K, 1.01325 bar, At your conditions, get actual flow as normal liters/min x 1.01325 bar/3 bar x 600 K/273.15 K (this assumes ideal gas law is good approximation and compressibility factor can be ignored) Recognize that lier is also a cubic decimeter to convert to cubic volume flow. Divide by area to get average velocity.
Is clear. Thank you.
#9
10-16-2011, 09:46 PM
 Unregistered Guest Posts: n/a
Re: converting normal litres/min to g/s

I have been given a fuel usage in a Diesel generator of 200 g per Kwh how much is that in litres per Kwh
#10
10-17-2011, 02:13 AM
 JohnS Moderator Join Date: Dec 2007 Location: SE Michigan, USA Posts: 9,535 Rep Power: 19
Re: converting normal litres/min to g/s

Quote:
 Originally Posted by Unregistered I have been given a fuel usage in a Diesel generator of 200 g per Kwh how much is that in litres per Kwh
Depends on the density of your diesel, which varies. However, a typical value is 0.84 kg/L or 0.238 L per kWh.

 Thread Tools Display Modes Linear Mode

 Posting Rules You may post new threads You may post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Main Forums     Convert and Calculate     Resources     General Chat

All times are GMT -8. The time now is 11:26 AM.