Psychrometrics Quiz Question

[NormChris]

Which is heavier, dry air or water vapor?

[bobby7388]

A

[i_got_ideas]

I vote for dry air.

[rob10]

dry air

[Roscoe]

just to be different it depends on the temperature.

Norm I know you can work the psychrometric calculator could you explain it to us sometime, if you already haven't.

[NormChris]

Let's see now, the clouds are a collection of water vapor and they are located where?

[Roscoe]

see I knew you were going to pull something like that.

dah hilt a hilt

[NormChris]

Originally posted by pjs
see I knew you were going to pull something like that.

dah hilt a hilt

Ok, so how do you explain fog on the ground?

[HVAC Pro]

Which is more important? 6% net profit or 2% gross profit?

[HVAC Pro]

Ooops wrong thread!

[NormChris]

Originally posted by HVAC Pro
Which is more important? 6% net profit or 2% gross profit?

If I knew the answer to that I would still be a contractor!

[i_got_ideas]

Originally posted by HVAC Pro
Which is more important? 6% net profit or 2% gross profit?

I belive most look at gross profit.

Because over-head can be reduced which would in turn increase net profit. In reality they are both important but a bank or something of the sorts is going to be looking more at gross profit.

[Edited by I_got_ideas on 07-20-2004 at 10:39 PM]

[i_got_ideas]

Fog on the ground means there is no dry air, the air is saturated.

Forgive me, grasping for staws to justify my answer but it sounds good.

You know, that sounds real good now that I read it again.



[Edited by I_got_ideas on 07-20-2004 at 10:40 PM]

[Carnak]

Dry air consists of oxygen O2 with a molecular weight of 32 and nitrogen N2 with a molecular weight of 28.

Water is obviously H20 meaning two hydrogens ( molecular weight of 2) and one oxygen molecular weight of 16. Therefore a water molecule 'weighs' 18.

Steam with a weight of 18 is lighter than something that is roughly 0.2x32 + 0.8x28 = 28.8. Air is actually a bit heavier however the math is simpler with 20% oxygen and 80% nitrogen.

[Carnak]

Originally posted by NormChris
Let's see now, the clouds are a collection of water vapor and they are located where?

We always seem to come back to clouds Norm. They are water droplets. Vapour is invisible. But what the hell keeps the droplets up there?

[i_got_ideas]

Please enlighten us with the answer Norm. Inquiring minds want to know.

[badboy]

Trick question Norm? Temp and pressure of air dictates water vapor.
Warm air holds more water than cold air.
clouds,
When air rises, it expands and gets colder.
The colder air cannot hold as much water as warm air.
As the temp and air pressure continue to drop, tiny water droplets grow together into clumps called cloud droplets.
At this point,the air becomes a visible cloud.
So it would seem to me,temp diff. Fog and cloud are same.Colder surface,fog. Warmer surface,cloud.

But i'm probobly way off!

[NormChris]

No trick, just common sense and good reasoning. Give it more thought.

[i_got_ideas]

I guess this illustrates the value of further education. However, how many techs REALLY need to know this on a daily basis?, just curious is all.

[Carnak]

Clouds which consist of water droplets are a bad anaolgy.

Have to look at molecular weights, daltons law of partial pressures, vapour pressure of water and ideal gas law to try to work things out