so water grains as mentioned here, would be similar to the EMC percent?
EMC
Moisture content in wood affects both the size and strength of lumber. If you know the EMC of the storage or manufacturing area (which is derived using temperature and humidity readings), you can also determine the moisture content of the wood stored there.
Sorry folks, it’s a trick question. The issue is totally different. The volume of air that the engine can take in with each cycle is essentially fixed. You can only use as much fuel as the air contains oxygen to burn, so the air is kept as cool as possible to maximise the amount of oxygen that it contains.
the dew point is a good one to watch…it stays the same as the temperature rises and the humidity falls
Yep, colder air is denser air. That is why when flying small planes in the winter you get better performance. More air to help with lift and more oxygen for the engine to burn. To keep this somewhat on topic, the denser (colder) the air is the less “extra space” for the water molecules to hang around in.
Eric
[quote author=Jeep link=topic=10275.msg76984#msg76984 date=1122583249]
Chris, you’ve no quite got it. In the example I gave,
"If outside air at 85
it tells you how much moisture could be in a pound of air at a given temperature.
Jeep’s table was by volume, cubic feet, not weight (or is that mass :? ). It would be very different per pound of air.
yea, my bad. speed reading gets me into trouble sometimes. The table IS maximum amount of water grains that a cubic foot of air can hold before it reaches saturation point and falls out.
[quote author=administrator link=topic=10275.msg77114#msg77114 date=1122639156]
I think it would help us to know the equivalent water grain values for your examples of 85
Specific Humidity , gm/totalKg
is that what is needed?
Well, I’m looking for absolute humidity, which is just a bit different than specific humidity. Here’s an description in metric terms.
Absolute humidity (expressed as grams of water vapor per cubic meter volume of air) is a measure of the actual amount of water vapor (moisture) in the air, regardless of the air’s temperature. The higher the amount of water vapor, the higher the absolute humidity. For example, a maximum of about 30 grams of water vapor can exist in a cubic meter volume of air with a temperature in the middle 80s.
SPECIFIC HUMIDITY refers to the weight (amount) of water vapor contained in a unit weight (amount) of air (expressed as grams of water vapor per kilogram of air). Absolute and specific humidity are quite similar in concept.
I’ve found these formula’s:
The vapor concentration (density of water vapor in a mixture) or absolute humidity, is defined as the ratio of the mass of water vapor Mv to the volume V occupied by the mixture.
Dv = Mv / V , expressed in grams/m3 or in grains/cu ft
This can be derived as follows from the equation PV = nRT:
Mv = nv x mw:
Dv = Mv /.V = nv x mw / V = mw x p / RT
where:
nv = number of moles of water in the volume V
mw = 18.016 gram (molecular mass of water)
p = partial pressure of water vapor [Pa]
R = 8.31436 Pa x m3 /
do you have an example, for a given temp/hum ?
as i have a program here that gives all sorts of stuff, which i have the code for,…
like density, kg per cubic meter
mixng ratios…
Q: So, is absolute humidity a good moisture variable?? A: NO, It is not constant even though the amount of mositure is
It would appear that this site is not in favor of using absolute humidity to measure moisture content…
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter5/expand_parcel.html
I found this page, which gives the steps you need to calculate absolute humidity. It’s different humidity calculations, just scroll down. I think between that and what you’ve got would do it.
http://www.vivoscuola.it/us/rsigpp3202/umidita/attivita/humidity_formulas.htm
i found that too
must have used the same google huh
try a new 10.27L zip download…
and the tag is %abshum%
Cool, I’m at work till 1:30 A.M… As soon as I get home I’ll d/l and try it out. Thanks Brian!
that wll mean you have not got the correct version yet…
try a new download…
OK, Downloaded again, and it’s showing 0.0
Ahhh…that will be absolute zero humidity 
Heh, it’s been absolute zero humidity for a couple of days now… my skin is REALLY starting to itch…
