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Firefighter Math

firefightermath.org

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Re: Firefighter Math

#21

Post by ak217 »

jcranmer wrote: post #20
johansch wrote: post #6

http://www.firefightermath.org/index.php?option=com_content&... "A 100-foot length of 1-inch diameter hose is charged with water. How many gallons of water are in that length of hose?" Ugh.

"A 100m length of 1cm hose is charged with water. How many liters (1 dm³) of water are in that length of hose?" That problem is still no fun to do in your head. If it's important to do frequently, it's not hard to memorize the constant for "1 ft of 1 in-diameter hose = X gallons" and then multiply as appropriate.

Actually, it's trivial to do in your head. 100 * 100 cubic centimeters of water = 10 liters. Times pi/4 to correct for the circular cross section, so approx. 8 liters.

Re: Firefighter Math

#22

Post by yardie »

ateesdalejr wrote: post #11
knz wrote: post #9

Earlier quoted context omitted.

The section on unit conversions ( http://www.firefightermath.org/index.php?option=com_content&... ) just makes me wonder why fire fighters don't use metric... "How many pints are in a 5-gallon pail? How many cups are in a 5-gallon pail?"

Probably because most firefighters were taught and grown up on the imperial system of measurement...

If they were taught in a US school for the last 40 years they were taught metric. If they were enlisted at any point in the last 30 years they were taught, and used, metric. If they can't handle the metric system then they probably aren't that good at math and are just using rote memorizations.

Re: Firefighter Math

#23

Post by stmw »

This is very cool! There should be an SRE version: "the mx4-large instance is filling memory at 5 megabytes-per-gallon, when will Datadog retrigger PagerDuty?"

Re: Firefighter Math

#24

Post by maxerickson »

johansch wrote: post #17
brooksgarrett wrote: post #15

Earlier quoted context omitted.

Speaking from experience, it's primarily due to 'tradition.' All of your combi-nozzles and rate control valves are rated and marked in GPM (Gallons per minute) and hose is purchased and stored as 50' sections. NFPA specifications for the hose required on a first due engine are in feet. A department can't decide to use metric alone. The entire industry first would need to support at the minimum both standards.

It's probably possible, somehow, to quantify how many americans perish every year because of this.

I bet it is close to 0.

In recent years, the total number of fire deaths is 3000 to 4000 per year:

https://www.usfa.fema.gov/data/statistics/fire_death_rates.h...

Many of those deaths will have happened regardless of the response.

In some sense, across 300 million people, even 3000 is close enough to zero (there's more than 2.5 million total deaths each year in the US). That doesn't mean that improving fire response isn't important, but it might not be a very good place to look for incremental improvements in mortality.

Re: Firefighter Math

#25

Post by pdkl95 »

taxicabjesus wrote: post #2

After I 'retired' from taxi-driving, the volunteer fire department for my grandfather's (deceased) rural cabin sent a bunch of us to the Arizona State Fire School [0]. This organization provides training for small fire departments that don't have the resources to run their own training. Topics covered include basic firefighting, how to drive a firetruck, fire investigation (arson?), etc. [0] https://www.facebook.com/…

> Those police officers put her in a bad situation, and it was my honor to help extricate her from the area around the county jail.

    /me stands and applauds
> "THIS IS NOT WHY WE CALLED YOU"

The more I think about it, the more I like the model that Michael Wood Jr. has been promoting, "Civilian Led Policing"[1], which attempts to directly fix this impedance mismatch between police goals and community goals.

Instead of police being directed an appointed or elected "chief" (that is necessarily entrenched in the usual political brouhaha), the police should be directed by more like a board of directors, with the members selected[2] from the community where the police have jurisdiction. Each local community should be directing how they want to be policed.

(It's not quite that simple - I'm simplifying to keep this short. See [1] for a more complete description)

[1] http://civilianledpolicing.org/#info

[2] Perhaps by something involving a jury-duty style lottery? It needs to be an equitable sample of the community.

Re: Firefighter Math

#26

Post by taxicabjesus »

marcosdumay wrote: post #18
taxicabjesus wrote: post #2

After I 'retired' from taxi-driving, the volunteer fire department for my grandfather's (deceased) rural cabin sent a bunch of us to the Arizona State Fire School [0]. This organization provides training for small fire departments that don't have the resources to run their own training. Topics covered include basic firefighting, how to drive a firetruck, fire investigation (arson?), etc. [0] https://www.facebook.com/…

> I don't know why the president of our volunteer fire department decided 3 of us needed to learn about Vehicle Extrication Maybe because when you need it, you need it instantly, so he wanted to always have somebody with that knowledge on the current turn?

Of the 3 of us who took 'extrication', there was myself, the volunteer fire department president's daughter, and a fellow who actually lives in that rural community full-time. The full-timer had been to fire school the year before to take a different class (pumps? how to drive a fire apparatus? I don't remember).

The most interesting thing for me was learning about the profession from the inside. I might've liked to have learned about driving fire trucks - maybe I'll go again.

Re: Firefighter Math

#27

Post by mindcrime »

johansch wrote: post #6

http://www.firefightermath.org/index.php?option=com_content&... "A 100-foot length of 1-inch diameter hose is charged with water. How many gallons of water are in that length of hose?" Ugh.

Don't worry, to a first approximation we can say that no firefighter on a fireground has ever had to make that calculation. It's semi-handy to know in terms of things like this:

5" supply hose holds about a gallon per foot of water when charged, and water weighs just a little more than 8 lbs per gallon, so a charged 100' section of 5" supply hose weighs over 800 lbs. So make sure you have the hose where you want it before charging it, because it's damn hard to move afterwards and the like.

In terms of doing math on the fireground, at least in a structural fire scenario (wildland firefighting has some other concerns) the single biggest one is usually flow-rate. That is, a crew has stretched a 200' pre-connected 2" attack line, and wants to go in flowing 200 gpm to attack the fire. As the engineer, what pressure do you configure on that discharge to give them their 200 gpm? Here's the kicker though... almost nobody sits there thinking "Well, the friction loss per foot of 2" hose at 200 gpm is x, multiply x by 200, assume a desired pressure of 100 psi at the nozzle, blah, blah, blah.". No, instead somebody precomputed the common configurations, wrote them on an index card, laminated it, and taped it to the pump panel. Plus the engineer probably has the really common ones memorized anyway, and/or has figured out a heuristic that's "good enough".

Re: Firefighter Math

#28

Post by mindcrime »

johansch wrote: post #17
brooksgarrett wrote: post #15

Earlier quoted context omitted.

Speaking from experience, it's primarily due to 'tradition.' All of your combi-nozzles and rate control valves are rated and marked in GPM (Gallons per minute) and hose is purchased and stored as 50' sections. NFPA specifications for the hose required on a first due engine are in feet. A department can't decide to use metric alone. The entire industry first would need to support at the minimum both standards.

It's probably possible, somehow, to quantify how many americans perish every year because of this.

I agree with @maxerickson, I'd bet that that number is approximately 0. The reasons people perish from fires rarely if ever have anything to do with a math mistake on something like this.

Re: Firefighter Math

#29

Post by taxicabjesus »

pdkl95 wrote: post #25
taxicabjesus wrote: post #2

After I 'retired' from taxi-driving, the volunteer fire department for my grandfather's (deceased) rural cabin sent a bunch of us to the Arizona State Fire School [0]. This organization provides training for small fire departments that don't have the resources to run their own training. Topics covered include basic firefighting, how to drive a firetruck, fire investigation (arson?), etc. [0] https://www.facebook.com/…

> Those police officers put her in a bad situation, and it was my honor to help extricate her from the area around the county jail. /me stands and applauds > "THIS IS NOT WHY WE CALLED YOU" The more I think about it, the more I like the model that Michael Wood Jr. has been promoting, "Civilian Led Policing"[1], which attempts to directly fix this impedance mismatch between police goals and community goals. Instead of…

> The more I think about it, the more I like the model that Michael Wood Jr. has been promoting, "Civilian Led Policing"[1], which attempts to directly fix this impedance mismatch between police goals and community goals.

Your link has some good ideas. Maybe civilian-led policing would get la policia to stop arresting anyone for anything. How does this address how the criminal justice system has standardized on harmful practices? "war on drugs", punishment for everything, fines for people who can't afford them, etc. Police have a very difficult job thanks to mistakes made by politicians.

One of the passengers mentioned here, the one whose family called the police for help... After that episode her doctor helped her become an alcoholic (Xanax); she ended up spending 2 years in prison for her 3rd DUI. She got a case of PTSD, and wasn't able to stay sober for long after her release. She's doing better now, no thanks to the system.

America's Make-Work Sheriff: The Anachronism of Joseph Arpaio is about how people are frequently harmed by their interactions with 'justice': http://www.taxiwars.org/2017/09/americas-make-work-sheriff-a...

Re: Firefighter Math

#30

Post by brooksgarrett »

maxerickson wrote: post #24
johansch wrote: post #17

Earlier quoted context omitted.

It's probably possible, somehow, to quantify how many americans perish every year because of this.

I bet it is close to 0. In recent years, the total number of fire deaths is 3000 to 4000 per year: https://www.usfa.fema.gov/data/statistics/fire_death_rates.h... Many of those deaths will have happened regardless of the response. In some sense, across 300 million people, even 3000 is close enough to zero (there's more than 2.5 million total deaths each year in the US). That doesn't mean that improving fire response…

I agree. I've never been on a fireground and had someone yell, "We lost the house because you didn't divide by 12!" Fireground math is a very rough science. Every engine in our district has pre calculated charts for every cross lay and discharge so you aren't doing the math on scene. Additionally, once you deploy line you have a radio and can ask the engineer to increase or decrease pressure with no math required.

A much bigger issue is the lack of recruitment and volunteerism in the American fire service. People simultaneously don't want to increase property taxes to fund career departments and they also don't want to volunteer. Communities can't have it both ways. Lack of staffing is a far greater risk than whether I'm dividing by 10 or 12.

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