Mass Flow Rate Conversion

Mike T., Swampeast MO

Then I got the time right...

Why though do they use a mass-flow measure instead of volume-flow?

With water and at with typical temps in hydronic heating systems I thought that the difference between mass and volume was essentially ignored except in gravity systems.

C.J.B

Conversion of a European based Mass flow rate (Kg/u)

Hoping someone may be able to help me with the conversion of a Kg/u in water flow rate terms into S.I or imperial units.
The particular unit is from a product manual by Jaga Design radiators in reference to there pressure drops across all there products.

C.J.B

Conversion of a European based Mass flow rate (Kg/u)

Hoping someone may be able to help me with the conversion of a Kg/u in water flow rate terms into S.I or imperial units.
The particular unit is from a product manual by Jaga Design radiators in reference to there pressure drops across all there products.
They refer to the pressure drop across there products in mmWK, which I found that 10.2mmWK = 1mBar and the water flow rate they refer to in Kg/u's, for the life of me I cant find what the (u) or for that matter what a Kg/u is equal to.
Any help would be very much appreciatted.

Mike T., Swampeast MO

Numbers on the graphs sure make me think that it's kilograms per hour but I cannot confirm. Found the same unit used a paper regarding water consumption for commercial food processing, but no explanation of the term.

Cannot find in any conversion table/program. Most searches for "kg/u" or similar bring up references to Uranium...

Christian Egli_2

For Flemish, press 3, uh?

A bit of translation will help. English to Dutch. Though Jaga sounds Scandinavian this company is homed in Belgium.

Thus,

water: water (pronounced waahter)

column: kolom

hour: uur (unpronounceable) u = h


1 kg/u * 1u/hour * 1 l/kg * 1 gal/3.785 l * 1hour/60 min = 0.0044 gal/min [GPM]


1 mmWK = 1 mmW.C.


1 mmW.C.* 1 inW.C./25.4 mmW.C. = 0.040 inW.C.

or

1 mmW.C. * 14.7 PSI/10000 mmW.C. = 0.00147 PSI


Isn't that funny? What do U think?

U is usually the symbol for potential in volts

u/min is often used for RPM

Christian Egli_2

Quick, how many pounds per gallon of water? per cubic feet?

Heat gets packed into water on a per mass basis, not volumetric, thus, it is far more precise to deal with mass flow rate. The same way steam is rated in a pound per hour basis so that you don't have to care to factor in a temperature-volume coefficient. It's better.

For hot water heating, the difference is not all that huge though, and jumping from mass to volume indiscriminately can be tolerated. This is particularly true for the rest of the world where 1 litre is equal to 1 kilogramme of water, no translation required.

Ron Schroeder

Quick, how many pounds per gallon of water? per cubic feet?

At what temperature??
# 62.416 pounds per cubic foot at 32°F
# 61.998 pounds per cubic foot at 100°F

Mike T., Swampeast MO

So you seriously consider the difference in volume of water between say 15°C and 75°C when designing systems for forced flow? In pounds per cubic foot that's down to the 5th significant decimal place.

C.J.B

Mass Flow Rate Conversion

Thanks for you're help guys, initially thought it might refer to a per hour basis but wasnt certain and tried to get a quick fix answer by searching the net.
Instead I should have run the numbers like I have just done and it all makes sense that the (u = 1hr).
Only being new to the game spose it all comes down to experience and the way you look at problems.

The statement that 1Kg of water is eqaul to 1ltr of water is very true and the differences at higer temps is minimal.
(density of water at 80c is 971.6 Kg/M3)
Sorry to bring up the Metric system thats all they teach us here at the land down under.
Thanks again guys.

Mike T., Swampeast MO

Thanks again Christian.

hour: uur (unpronounceable) u = h

Both sharp and gutteral, right?