And I thought I was bad at math...

[clarsct]

I've never seen a 350,000 gal tower before, but as I posted previously, 180,000 gal is not unreasonable.



Agree. But flow is equally as important as pressure.

This does not conform to my experience. Cite please? A sprinkler head will "function" at almost 0 flow and 0 pressure, i.e. the link will fuze, the glycerine will burst, etc. It just needs adequate flow and pressure to protect the occupancy.

Well, the themral coupling should function, yes, but in order to have fire protection, the water must hit the deflector at a pressure such that it disperses.
For most industrial systems, this is at or near 95 psi. Much lower than that, and the water dribbles out in a fashion that does not allow for the cooling action of evaporation. Many manufacturers recommend 175 psi, as mentioned in NFPA 13.
http://www.globesprinkler.com/files/A-652.pdf

But in practice 100 PSI in the line seems to be sufficient.

I'm afraid most of my experience is hands-on as well. We run at about 130 PSI in our lines, because of the loss of pressure due to friction and line length. It ensures at least 100 PSI at the heads.

Maybe you were thinking of residential sprinklers?

.
Again, I question the 75 psi statement. The rest of the statement sounds like you are saying with "low flow" heads (whatever they are) you have to decrease the sq. ft. coverage/head?? Please explain what you mean.
Of course. But what does this have to do with water flow/pressure/extinguishing capability?

Low flow heads flow less water, so yes, you would need more head to flow as much water to the same area, but you can run at a lower water pressure. Less pressure means less water per second. Less water per second means less extinguishing capabilities.

Looking over some of the manufacturers, I see they do not offer the low-flow heads anymore. Maybe the revamp of NFPA 13 did them in. It looks like the 175 PSI head is standard now, with a high pressure version at 300PSI.*shrug* I might have outdated information about those. We never really used them anyway.

Good point. Hadn't considered that.


Possibly, but my experience is that you just take suction from the city underground main (assuming you have a reliable supply there), and then provide a booster pump at regular intervals as you increase elevation

Which was the kind of system I was thinking about

Not sure what you are talking about here exactly.

You create suction, which can water hammer a system. The tank creates a reservior that cushions this intial suction, thus reducing the hammer effect. A water hammer is a wave created within a pipe caused by sudden changes in water pressure. If you suddenly pressurize(or depressurize) a pipe full of water, it creates a wave that transverses the length of the pipe. This wave can cause damage and even break water mains.

Agree. see above.

Actually, if you have a gravity system, you just use a small fill pump to continually make up for any pipe leakage, etc. In a fire situation, once the gravity tank is empty, you are SOL as that little pump is ineffective.

That, too!

Actually, the testing on a wet-pipe sprinkler system as far as water usage is concerned is rather small. The two inch drain where the riser enters the building is probably tested monthly for about 30 seconds. The inspector's test connection (which simulates flow from one sprinkler head) is probably tested twice a year.

>!<
Twice a year?! Every month! The inspector's test and the 2 in riser drain ought to be tested monthly. It's not a lot of water, but it adds up, especially with the number of systems you're going to have in a building the size of the Towers, and when you talk about damping effects.

On large systems, there are sectional valves that can be closed to avert having to drain an entire system.

Yes, but it rather negates the idea of flushing a system.

 

[OMGturt1es]

Do you have a cite for this?

Aren't all three of the asbestosform materials you mentioned subject to the same permissible exposure limit for inhalation?

In the US, OSHA 1910.1001 defines "Asbestos" thusly:

"Asbestos" includes chrysotile, amosite, crocidolite, tremolite asbestos, anthophyllite asbestos, actinolite asbestos, and any of these minerals that have been chemically treated and/or altered.

I'm wondering why it is subject to the same permissible exposure limit if it is, as you put it, "not very dangerous, at the worst".

from what i understand, the amphibole asbestos (mainly amosite and crocidolite) are the worst, as they tend consist of "barbed" fibers. chrystole fibers aren't barbed, and therefore are less likely to lodge within the lung tissue. i don't have the sources handy, but from what i understand, there have been a number of studies on chrysotile, which have failed to produce any data to prove that chrysotile causes any serious lung problems. in one case, lung cancer rates among miners and their families who were exposed to chrysotile asbestos were actually lower than those of the general population.

my min/lith professor's husband, apparently, has dealt a fair bit with abestos based inhalation hazards, so we spent a good week studying asbestos forming minerals and inhalation hazards. this information is straight from the professor's mouth. however, that chrysotile is not considered the "bad asbestos" was also echoed some years back in my physical geology text book.

as to why the government treats it all the same? good question. i think it's a mix between asbestos paranoia and "feel good" legislation. perhaps there's also justified fear that future studies could prove a link between chrysotile and lung cancer? or, perhaps my professor is full of ****?

i'll dig out my mineralogy book a bit later and see if it mentions anything specific...

 

[OMGturt1es]

Do the other credible sources that say the same thing only speak to the asbestos-cement industry, or to all applications?

i was taught that the reason that chrysotile wasn't nearly so harmful had to do with the shape of its fibors. under a microscope, it's pretty easy to see the difference between, say, amosite and chrysotile.

here's an FAQ at an obviously biased site:
http://www.chrysotile.com/en/chrysotile/hltsfty/questions.aspx

it does seem to provide sources for its claims however, so perhaps you can do some digging from there.

it's certainly possible that what i was taught wasn't completely true, but my point of posting was that it's certainly not very intellectually honest to claim that workers were knowingly sent into a horrible situation-- at least, not if the situation is considered horrible because chrystotile asbestos is present. weather right or wrong, it seems that a lot of credible sources claim that chrysotile isn't that dangerous.

the reason, in fact, chrysotile was used for fire proofing on the WTC buildings-- again, learned in school, but was not given a source-- was because workers started getting sick at the start, when they were spraying the beams with amphibole asbestos.

 

[OMGturt1es]

btw, i was going to provide a bit more of an explaination in my original post, both about chrysotile fibers, and about the purpose of my post, but i posted in haste because i was running late for the christmas celebrations.

 

[Dave_46]

From memory, chrysotile asbestos is serpentine (curly), and amphibole fibres are straight. Amphibole fibres can split down their length, and become very thin, which is why they are more dangerous than serpentine fibres. It has to do with the way that the body fights foreign matter, and the very thin fibres are more dangerous.

Having said that, the serpentine fibres are still dangerous, and in the UK the threshold levels for exposure are the same for both types.

From Control of Asbestos Regulations 2006

"Worker exposure must be below the airborne exposure limit (Control Limit). The Asbestos Regulations have a single Control Limit for all types of asbestos of 0.1 fibres per cm3. A Control Limit is a maximum concentration of asbestos fibres in the air (averaged over any continuous 4 hour period) that must not be exceeded."

source http://www.hse.gov.uk/asbestos/regulations.htm

More info http://www.hse.gov.uk/asbestos/

Guess who did a course on asbestos surveying recently

Dave

 

[Mr. Skinny]

Well, the themral coupling should function, yes, but in order to have fire protection, the water must hit the deflector at a pressure such that it disperses.
For most industrial systems, this is at or near 95 psi. Much lower than that, and the water dribbles out in a fashion that does not allow for the cooling action of evaporation. Many manufacturers recommend 175 psi, as mentioned in NFPA 13.
http://www.globesprinkler.com/files/A-652.pdf

But in practice 100 PSI in the line seems to be sufficient.

I'm afraid most of my experience is hands-on as well. We run at about 130 PSI in our lines, because of the loss of pressure due to friction and line length. It ensures at least 100 PSI at the heads.

Maybe you were thinking of residential sprinklers?
Low flow heads flow less water, so yes, you would need more head to flow as much water to the same area, but you can run at a lower water pressure. Less pressure means less water per second. Less water per second means less extinguishing capabilities.

I'm on two weeks leave from work now, so I don't have my NFPA 13 available, but I'll check it when I return.

My hands on experience is over 25 years old, but I recall testing city water supplies that had static pressures of less than 75 psi (with residuals in the 50's) that were entirely capable of meeting the sprinkler demand without a booster pump, even after subtracting hose stream demand.

The link you gave me can be intrepreted as saying the head can withstand 175 psi working pressure, but it doesn't say (to me at least) that 175 is the minimum required to produce proper discharge pattern.

I guess I'll abandon this issue for now since it's derailing the thread slightly. I'll take it up with you in PM when I return to work.

Thanks for the input.

Skinny

 

[Mr. Skinny]

From memory, chrysotile asbestos is serpentine (curly), and amphibole fibres are straight. Amphibole fibres can split down their length, and become very thin, which is why they are more dangerous than serpentine fibres. It has to do with the way that the body fights foreign matter, and the very thin fibres are more dangerous.

Having said that, the serpentine fibres are still dangerous, and in the UK the threshold levels for exposure are the same for both types.

From Control of Asbestos Regulations 2006

"Worker exposure must be below the airborne exposure limit (Control Limit). The Asbestos Regulations have a single Control Limit for all types of asbestos of 0.1 fibres per cm3. A Control Limit is a maximum concentration of asbestos fibres in the air (averaged over any continuous 4 hour period) that must not be exceeded."

source http://www.hse.gov.uk/asbestos/regulations.htm

More info http://www.hse.gov.uk/asbestos/

Guess who did a course on asbestos surveying recently

Dave

Thanks for the info.

I suppose my whole point here is that since the US (and UK) treats chrysotile asbestos exposures the same as other forms of asbestos, arguing with a CTer that

there's plently of evidence that chrysotile is generally, well, not very dangerous, at the worst.

is gonna be a non-starter, IMHO.

 

[jaydeehess]

Sorry to get technical on this, but the concept of the tonnage of a ship is anything but clear. First of all, tonnage in ships frequently refers to volume and has nothing to do with mass. Then, there's the displacement weight - that has nothing to do with what the ship weighs, either. It's the mass of the water that the ship displaces. The Nimitz displaces about 97,000 tons of water fully loaded. Then there's the actual weight of the unloaded ship which can be very different from the full loadout displacement.

All in all, I think there are better comparisons to be made than to the Nimitz. Maybe the Eisenhower or the Reagan, but definitely not the Nimitz.

I did indeed refer to displacement. wkipedia puts this at 120,000 tons for the Nimitz class.

At any rate, no matter what spec for mass you choose for an aircraft carrier, 500,000,000 tons is several thousand times that number and a full sized aircraft carrier is comparable in total volume to one WTC tower. This should make it patently obvious even to a woo-woo that the spec, 500,000,000 tons, is waaaay off.

 

[Gravy]

By the by, here's what tanks were actually in the towers:

Four reserve water storage tanks were provided in WTC 1 to supply the standpipes. Each tank had a holding capacity of 5,000 gal for a total of 20,000 gal of water dedicated for manual fire suppression. These tanks were located on floors 20, 41, 75, and 110.

The water storage tank located on the 20th floor of WTC 1 supplied water to the sub-grade loops and the low zone standpipes in both towers. A similar tank was not provided in WTC 2.

Three reserve water storage tanks were provided in WTC 2 to supply the standpipes. These tanks were located on floors 42, 76, and 110. (total of 15,000 gal)

Two parallel 5,000 gal water storage tanks were provided on the 110th floor in each of the towers. These tanks provided a dedicated water supply of 10,000 gal for the high and mid-level zone sprinkler systems.

The 5,000 gal water storage tanks located in the 41st floor level mechanical rooms were arranged to provide the primary water supply for the low zone sprinkler systems and the standpipe systems zone serving floors 8 through 31. Therefore, a minimum of 5,000 gal was provided for the standpipe and sprinkler systems in each tower. Since each tank was also equipped with a 2 in. diameter automatic fill line supplied by the domestic water system, the volume of water in the tank would be partially replenished as the water was depleted from the tank.

(in addition, the complex had 12 manual and automatic fire pumps, ranging from 500 to 1500 gpm,and of course siamese connections)

NIST NCSTAR 1-4B Fire Suppression Systems, pgs 29-30 http://wtc.nist.gov/oct05NCSTAR1-4index.htm

 

[JonnyFive]

By the by, here's what tanks were actually in the towers:

(snip)

So, what you're really saying is that on the one mechanical floor on the 43rd floor, the towers held a massive two billion gallon tank for their magical fire suppression system that would've easily extinguished the fires and healed the towers' damage if the system hadn't been taken out by the government agents that were disguised as harmless rodents?

[/insane hijack]

We've developed two parallel concepts of the Twin Towers: The real ones, and the fantasy ones the CTist have built in their minds. The fantasy towers, of course, had concrete cores, only one mechanical floor, and a 180,000 gallon tank on the top. Also, they were magic and couldn't be destroyed except through massive amounts of explosives or a death beam from space.

 

[Crungy]

Thanks for that info. As expected, it's a much more sensible fire supression design than a 180,000 gallon mothership perched on top as suggested (and no doubt will not be corrected in any future debates) by our CT friends. For a building with exterme verticality, such as the Trade Center tower, a 5000 gallon tank is large. In a large warehouse or campus type building with minimum height, support usually isn't as much of an issue and 100,000 gallon tanks are the norm.

Since each tank was also equipped with a 2 in. diameter automatic fill line supplied by the domestic water system,

Interesting. I wonder if this is a mistake? This reads as if there was no fire line into the building, and the sprinkler system was fed of the your standard potable cold water!? Our old plumbing/fire protection department head was from Jersey and told me that the NYC codes were whacked, but.......

 

[Free Thinkr]

Sorry to get technical on this, but the concept of the tonnage of a ship is anything but clear. First of all, tonnage in ships frequently refers to volume and has nothing to do with mass. Then, there's the displacement weight - that has nothing to do with what the ship weighs, either. It's the mass of the water that the ship displaces.

Correct me if I'm wrong, but it seems to me the weight of the water the ship displaces is exactly equal to the weight of the ship doing the displacing.

 

[Spins]

Correct me if I'm wrong, but it seems to me the weight of the water the ship displaces is exactly equal to the weight of the ship doing the displacing.

If you inflate a balloon and fully submerge it underwater does it displace water equal to the weight of the balloon? No, an object fully submerged in water displaces an amount of water equal in volume to the object.

 

[JimBenArm]

If you inflate a balloon and fully submerge it underwater does it displace water equal to the weight of the balloon? No, an object fully submerged in water displaces an amount of water equal in volume to the object.

Actually, you are both right. If the ship is to stay floating, it displaces a weight of water equal to the weight of the ship. If it submerges, then it displaces a volume of water equal to the volume of the ship.

Take it from an old submarine sailor!

 

[Hellbound]

Yep.

The weight of the water displaced is always equal to the downward force being applied. For a ship, or other object floating on the surface, the only downward force is gravity, thus displacement=weight.

In the balloon example, the weight of water displaced is equal to the force being used to push the balloon down. if you let it float, the water displaced would match the weight of the balloon.

 

[Spins]

Actually, you are both right. If the ship is to stay floating, it displaces a weight of water equal to the weight of the ship. If it submerges, then it displaces a volume of water equal to the volume of the ship.

Take it from an old submarine sailor!

Yeah, thinking about it again in the case of a ship that is afloat the amount of water being displaced is directly related to its weight.

 

[uk_dave]

We've developed two parallel concepts of the Twin Towers: The real ones, and the fantasy ones the CTist have built in their minds. The fantasy towers, of course, had concrete cores, only one mechanical floor, and a 180,000 gallon tank on the top. Also, they were magic and couldn't be destroyed except through massive amounts of explosives or a death beam from space.

ahhhh but you forgot to add:

"....couldn't be destroyed except through massive amounts of explosives or a death beam from space, even though they were corroded enough to require demolition by 2007"

Perfecto!

 

[Free Thinkr]

Actually, you are both right. If the ship is to stay floating, it displaces a weight of water equal to the weight of the ship. If it submerges, then it displaces a volume of water equal to the volume of the ship.

Take it from an old submarine sailor!

Well, right. I thought about writing "a floating object" rather than "a ship," but since we were only talking about displacement and whether it is or is not a measure of the ship's weight, I didn't bother.

 

[Mr. Skinny]

Interesting. I wonder if this is a mistake? This reads as if there was no fire line into the building, and the sprinkler system was fed of the your standard potable cold water!? Our old plumbing/fire protection department head was from Jersey and told me that the NYC codes were whacked, but.......

I took this to mean that a 2 inch fill line was provided to maintain the water level in the tanks.

There is water loss due to leakage, running 2 inch drains at risers, running inspectors test connections to check alarms, etc., that needs to be replenished.

In a fire situation, this 2 inch line is not expected to be able to keep up with the sprinkler water demand. It just makes up for small losses.

ETA: Most sprinkler systems are fed off the standard potable cold water lines in the street. They just have their own lead-ins off the street main. But yeah, sprinkler water is essentially the same as potable water. It's just that it becomes non-potable after it sits around in a suction tank or in the sprinkler piping for a while.

 

[Crungy]

I took this to mean that a 2 inch fill line was provided to maintain the water level in the tanks.

There is water loss due to leakage, running 2 inch drains at risers, running inspectors test connections to check alarms, etc., that needs to be replenished.

In a fire situation, this 2 inch line is not expected to be able to keep up with the sprinkler water demand. It just makes up for small losses.

ETA: Most sprinkler systems are fed off the standard potable cold water lines in the street. They just have their own lead-ins off the street main. But yeah, sprinkler water is essentially the same as potable water. It's just that it becomes non-potable after it sits around in a suction tank or in the sprinkler piping for a while.

I agree that it's a simple water make-up feed, but was there a dedicated fire piping system in the towers or was everything served from the cold water piping. That's what I'm confused about. If there isn't a dedicated main, how was the water metering handled? Who's payin' for all this sprinkler replenishing? Is this type of setup common out east? I've never encountered this setup in any building in the humble midwest here in Chicago. The fire lines are always separate from the domestic potable.

Regardless. I'm glad that I finally learned the basic outline of the fire protection system in the WTC Towers.

Btw, I'm sure you are aware that sprinkler water is the absolute nastiest water on the planet. I remember the first time I was exposed to a system purge. The Hollywood movies all make it appear to be your regular sparkling clean water. Uh-uh!