It's unlikely an urban fire department is set up for any significant amount of drafting (pulling water from surface sources), if it's something they can do at all.
You're absolutely right though, if you want big water, that's the way to get it. It's just that "big water" doesn't even begin to approach the scale of the water that would be necessary to directly fight this fire.
It's unlikely an urban fire department is set up for any significant amount of drafting (pulling water from surface sources), if it's something they can do at all.
SFFD trucks have that capability, and it was used in the 1989 earthquake. It's intended for pulling water from the underground cisterns marked by a big ring of bricks in SF intersections.
Terrible for the equipment to run salt water, but they had to.
I thought SFFD was some brand used by the French, but of course it's just USA-centric naming. (Took me forever to understand BART and I still have to look up name-based time zones like MST, which, no, thanks Wikipedia, is not Malaysia Standard Time at +8 but Mountain time at -7.)
For anyone else confused: this earthquake was in San Francisco and this is about their Fire Department. It doesn't mean that French fire trucks have that capability 30 years later.
It's unlikely an urban fire department is set up for any significant amount of drafting (pulling water from surface sources), if it's something they can do at all.
My understanding, which is probably quite out of date, is that it's mostly harbor firefighting boats which had this ability.
A coworker of mine points out that many of the San Francisco manholes are actually covers for cisterns of water, which exist primarily for fighting fires after an earthquake possibly takes out the water mains and starts many fires. I should hope that San Francisco fire trucks can draft water to use these.
Park the truck next to the cistern. Connect a length of hose to the pump supply, drop the hose into the cistern. The pump will move water until it loses suction pressure.
Is the hose to be dropped into the cistern different from the other hoses? I would expect it to be reinforced, such that it wouldn't collapse from air pressure. Hoses downstream from a high pressure pump wouldn't need such reinforcement. However, it's different upstream from such pumps.
You can recognize the cisterns because there are big (like 20 ft in diameter) brick circles inlaid into the street in SF to mark the cisterns. Neat once you know what to look for
> It's unlikely an urban fire department is set up for any significant amount of drafting (pulling water from surface sources), if it's something they can do at all.
London Fire Brigade for example has nine special pumps that can draw 2000 gallons a minute each from river or lake supplies. So that's 18,000 gallons a minute just from them.
Yeah, but that's not "a significant amount". It's certainly less than half of what you would need to fight this fire head on. That's also assuming all those engines are in-service, staffed, and can get there and get set up within a reasonable amount of time.
I would expect the fire department of a large city with navigable waterways to have fireboats, though, which by their very nature draft water. Even if the boat's own nozzles don't reach. they can generally be used as pumps for hoses on shore.
The devil is in the details. A "short" distance on a "small" island might well amount to a huge amount of hose. Then there's the logistics of getting all of that in place and hooked up. The trucks on site would need to pump to increase the pressure to usable levels, and all of that would have to be compatible. Getting enough trucks onsite might be a logistical challenge just in itself.
The real world is complex. It's not all like software or taking multiple choice exams. Again the devil is in the details. Pay really close attention to the map legend. It looks like there's nearly 200 feet of distance from the closest water shown on that map and the nearest side of the cathedral. I really doubt that all fire trucks carry 200 feet of hard suction hose, or have pumps designed to draft through 200 feet of hard hose.
"The NFPA 1901, Standard for Automotive Fire Apparatus – Requires pumpers to carry:
15 feet of large soft sleeve hose or 20 feet of hard suction hose"
You would never try to draft through 200 feet of hard suction. In fact, I'm relatively sure it would be impossible, since no matter how well you tighten the connections, there's pretty much always going to be a minute amount of vacuum loss at each coupling. In practice, few fire departments ever draft though more than 20 feet (2 sections) of hard suction, and even then it can be a challenge getting the pump primed, depending on any elevation difference between the water surface and the engine location, etc.
In real life, if you were going to draft in an environment like this, (leaving aside any reference to fire boats for a moment), you'd drive an engine to within 20' or so of the water, have it draft, and then relay water to the fire scene using (usually) 5" LDH. But sometimes even getting an engine to within 20' of the water can be a challenge, based on the geography and circumstances.
If the body of water you're drafting from is (strongly) subject to tides, that adds another complicating factor as your water source is now moving around, which could require constant re-positioning of the apparatus.
Lay people always see fires near large bodies of water and think "Why is water supply a problem, they're surrounded by water?!?" But it's often more complicated than that.
Source: was a firefighter and firefighting instructor for about a decade in a former life.
Also, even if you had a pump by the river, hand-jacking that length of LDH requires a huge amount of physical effort, and would tie up a lot of manpower during a critical phase of the operation.
I don't have to pay close attention to the map. I've been there. It is absolutely close enough to the river to have hoses running directly from it. The fact that they didn't use it suggests it probably wasn't such a good idea, we are only dudes writing on the internet, they are firefighters with experience doing their job.
I wasn't able to find any hard sources, but I don't see any evidence that the Paris Fire Brigade has any boats with any significant pumping capacity. Most of their boats seem to be rescue/dive focused, with small master stream deck guns.
Yeah, I've seen at least two draft lines running. But at best that's going to be 3-4k GPM. Enough for a couple of those big water streams. You'd need >10x that to fight a fire like this head on (which they clearly didn't have, since they immediately went to salvage and exposure protection measures)
You're absolutely right though, if you want big water, that's the way to get it. It's just that "big water" doesn't even begin to approach the scale of the water that would be necessary to directly fight this fire.