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Why NB, Weber, etc. call it a water pan

Mark

somebody shut me the fark up.
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Mark
Sorry for the redundancy of this post for those of you that already saw it in my heat shield post but Phil and I thought this discussion important enough to make it a seperate thread.

Water is pretty amazing stuff when you think about it and these properties make it the ideal substance for the water pan. Hopefully, the information below shows why:

The specific heat capacity of sand is less than 0.2 Btu/lb F
The specific heat capacity of water is exactly 1.0 Btu/lb F

This means a pound of water can hold over 5 times the heat of a pound of dry sand. This also means that water is nature's perfect heat sink and will control smoke chamber temperature swings better than anything else.

On top of that, water at 212°F (0 P.S.I. Gage) is changed to steam at the same temperature by the addition of 970 BTUs per pound. This also controls temperature swings.

Finally, water evaporation is assisted by the vapor pressure gradient between the hot, dry smoke entering the smoke chamber and the surface of the water in the water pan.

So while you can use sand or even kitty litter (ugh!) if you want to and may even produce good Q doing so, water will help reduce the variables thus improve your odds of prodicing consistantly good Q.

Hope this helps.
 
:D
Still prefer the ease, convenience and clean up that comes with using sand.
StL Mike
 
Okay - guess I'm sold with water but I'm really dumb at this science stuff. Here's why my dumb ass has difficulty with the above. Isn't sand capable of getting extremely hotter than water? Water hits 212 max, while sand, being right next to baffle and fire will get much hotter. If you cover the sand in foil it would seem to have less capability of losing heat, and because of the higher heat, radiate it out of the pan better. Also, water evaporates and sand doesn't. Just some additional things that seemingly should be considered. Mind you - I've never used anything but water.
 
Yeah, sand can get hotter than 212. May one of the sand advocates could monitor the sand temp some time?
 
Now correct me if I'm wrong, but water gets hotter than 212.

Water boils at 212. But it continues to get hotter.

It does not hit instant evaporation at 212. Otherwise the water is gone in a "poof". It continues to get hotter, up to a point, doesnt it?

If you add stuff to the pan, especially something with sugar, I am sure it gets hotter, cuz when I make sugar candy with the kids, I am boiling sugar and water to over 300*

Granted I am not advocating turning the warter pan into a 3 gallon lollipop of pork POOPIE. I just think it must go higher than 212, but I'm not that technical so maybe not.
 
Water will stay at that temp unless under pressure. All extra energy is converted to steam and released. This is why you can boil water in a paper cup. take one of those popcorn tubs, fill it with water and but it on your turkey fryer burner. You will not burn the container, and the water will boil.
 
I set 2 pans outside about 3 hours ago. The first I filled with water, the second I filled with sand. I just measured the temperature of both, and both are colder than a witch's tit.

All kidding aside, thanks for the info Mark. I geuss now it just comes down to personal preference. I will probably continue to use water in my pan, as I always have. It would however be interesting to get the perspective of a designer at one of these factories to give us the complete science behind the use of a water pan. Beyond that, I don't see the that either is wrong. Nobody using either method seems to have any complaint about the Q that they turn out. If any of the sand users were turning out dry ass Q, I imagine that they would probably switch back to water in the water pan.

Now, what are we going to do about all of these star-bellied sneetches. (Any one remember that reference?)
 
John:

what do you estimate the sand weighed?
 
I'd guess ~4 lbs seems that's what I used I thnik. Need a water guy to do the same thing.
 
I suspect the sand takes longer to heat but retains the heat longer. Just a guess.
 
john said:
I am going to do the same test sometime this week with water. That way all the same equipment/environment is used.

Be sure your probe is bare.
 
What about a pan filled 3/4 with sand, then pour in water till the sand is saturated and the water is about an inch above it? Wouldn't the sand hold a higher heat, which it could distribute to the water, which vaporizes and heats the chamber as the temps fall?
 
i thought that myself. The two of them may satisfy the the skeptics. I like the idea of the steam in the chamber.
 
How do you do the comment thing when posting? I wanted say that Mark
said
The specific heat capacity of sand is less than 0.2 Btu/lb F
The specific heat capacity of water is exactly 1.0 Btu/lb F

This means a pound of water can hold over 5 times the heat of a pound of dry sand. This also means that water is nature's perfect heat sink and will control smoke chamber temperature swings better than anything else.

but I didn't know where to put that on the form


I really should know about this topic because I took Thermodynamics at UT - but that was way way many years ago and not very practical - bunch of simultaneous differential equations.

BUT - this didn't seem intuitively correct to me - so brief WEB search shows that specific heat capacity is the amount of BTUs required to raise the temp of something 1 degree - so to me all this says is that it takes longer to heat sand up to the same temp as water. I don't t think this translates to how much "heat" (BTUs) is "stored" in there. The sand will get hotter - water can get lower than zero but only marginally higher than 212 my gut feel is that sand would contribute more heat after getting to temp.

Another BUT is that the heat from the water is going to primarily convection (hot steam) while the heat from the sand is going to be primarily radiant. I think the basic spirit of Q would say you want convention heat not radiant

R
 
Amen. Didn't take no class, leaned the hard way experience.
 
I'm only a communications major :D but living on the Gulf coast I do know that the water in the Gulf holds it's heat and moderates temperatures here on the coast much more than the sand :D

During the summer the sand will get very hot (ouch, ooh, ohhhh, hot hot hot!) and the water is "cooler" but the water will hold it's (for example) 86 degrees overnight while the sand cools off within a couple of hours of no sunlight.

Unscientific, yes!! Sometimes ya gotta love empirical data! :D

I still use water in my ECB -- guess the dry vs. moist heat was my reason.
 
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