Put on your thinking caps, need help with puzzler

Sailah

How fast would a room fill with steam assuming none of it collapsed as condensate? I know there are variables.

Say we had a box 10'x10'x10', 1" steam pipe @ 5PSIG. All steam stays in vapor form. How long before steam displaced all the air? I'm trying to solve by using steam @ 1600x volume of water but my little brain is fried from all the fumes form my snowblower.

We're talking theoretical here, so assume everything works perfectly.

How about a football stadium?

Fred

I assume the air is being displaced (vented) at the same rate steam is being fed or is there a vacuum in that box?

Gsmith

Well as an approximation, if it was air traveling at 6,000 feet per minute, a reasonably fast velocity for piped air, the air flow would be about 45 cubic feet per minute, so it might take 22 minutes to fully displace the original air content of the room

Sailah

Fred said:

I assume the air is being displaced (vented) at the same rate steam is being fed or is there a vacuum in that box?

Right, perfect conditions, no vacuum, just good ole air that gets replaced exactly as steam comes in.

Gary Smith said:

Well as an approximation, if it was air traveling at 6,000 feet per minute, a reasonably fast velocity for piped air, the air flow would be about 45 cubic feet per minute, so it might take 22 minutes to fully displace the original air content of the room

Hmmm, this may not be such an exciting demonstration point as I thought lol

When I would be using the steam rack at Barnes & Jones, we had 1" pipe and about 6 PSIG. If you cranked the steam on full bore it would seemingly fill a 10' cubed space in seconds. Course I never did that but even leaving it blowing for 4-5 seconds was impressive. I was thinking 10 seconds for a 10' room but that was just a hunch with no math behind it.

Sailah

OK so I had some delicious ham and split pea soup and the brain is back.

See if this makes sense:

Take a Spirax Sarco FT125 2" steam trap. It has an orifice of 0.332"

According to my steam loss calculator (from a utility company), if it was fully failed it would be losing 669 lbs/hr of steam at 135 PSIG. I'm using that pressure because I'm monitoring a hospital with exactly this scenario.


1 lb of steam at 0 PSIG occupies 27 cubic feet per Mr Holohan

So in theory if it was filling an empty space it would displace 18,064 ft^3/hr.

The NRG stadium in Houston is 90 million cubic feet.

So right around 4982 hours or just over a half a year.

I'm trying to figure out a way to hammer home how much steam is lost by filling a football stadium.

Does that sound about right or is my math way off?

And this hospital runs steam 8760 hours/yr so this fully failed trap is essentially filling almost 2 stadiums per year

JUGHNE

Would it not come down to the air venting rate of the 10 x 10 box or the stadium?
Just like a rad or steam main, we know the volume and incoming pressure but what size of vent is on it? #40 or big mouth?

Sailah

I guess think about it this way, I'm "pouring" this steam (which never collapses) into the football stadium. Just trying to give a size to how much this steam would be. We aren't venting it so to speak.

Although I'd probably want some bigger vents than a Big Mouth...

SeymourCates

@Sailah

Your calculations are very close to perfect. At 5 psig, , 1 lb. of steam occupies 32 ft^3. The displacement is 21,408 ft^3/hr.