Ask Mike: Putting out fires
Hey Guys,
Unless you’re either dim or a dog, you’re probably aware of the intended purpose of fire hydrants. What’s less obvious (to me, anyway) is how they actually work.
As is often the case when I have a tough question, I asked the Yahoo! Answers community for help. I received several great responses, including a few with some choice links.
Believe it or not, fire hydrants actually have an interesting history. A guy named Birdsill Holly Jr. didn’t exactly “invent” them, but the “innovations he introduced are largely responsible for the fire hydrant we take for granted today.” In 1863, Holly’s company introduced an “integrated system” that delivered a steady stream of water across cities for the purpose of fire protection. Over the course of his life, Mr. Holly was awarded 150 patents — second only to Thomas Edison.
So how does Holly’s invention actually work? Another responder, Kate, explains that the process is actually pretty simple. According to the Cornell Center for Materials Research, “the water that comes out of the hydrant is the same water that comes into homes, businesses, and schools.” Firefighters attach hoses to the hydrant and run it to the truck. There, the pressure of the water is increased via pumps, making it powerful enough to fight fires.
The link from Cornell also points out an interesting bit of trivia — you know how in movies, whenever a car runs into a fire hydrant, water gushes up hundreds of feet? Well, in real life, this is nearly impossible because there is usually no water stored in the upper part of the barrel. The water is stored far below the ground to avoid having the pipes freeze. Darn Hollywood — always stretching the truth.
Thanks for reading,
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Didn’t know that one. Interesting. Thanks for posting!
Mike, Actually it is possible for the water to spray up and out of a fire hydrant if broken off at ground level. It would depend on whether or not the shaft that controls and shuts off the water at the underground pipe connection is yanked out or turned on upon impact or from the very action of being torn apart. These things work like a yard hydrant, in that the water is shut off deep in the pipe, usually at the connection to the main line, by a long shaft that comes out at the large nut on the top of the hydrant. That’s why the firemen have to turn that big hex nut with the large wrench to get water flow into the pumpers.
soundss all wet although I have gusing fire hydant
that is correct sir.
A friend of mine once got drunk and hit a hydrant with her car. She drove off ans noticed her car was making weird noises, so she pulled over, called my roomate and asked us to help her out. When we got there, we looked under the car and found a frigin fire hydrant stuck to the car. We pulled it out, and stuck it in the back seat. Later, we cleaned it up and put it next to her fireplace. Hey, it’s my only fire hydrant story! I had to tell it on the fire hydrant blog.
I did not know that firefighters, when using a hydrant, ran the hose to their truck. I always thought that they hooked the hose up to the hydrant and aimed it directly at the fire.
Actually there is a little more to part of your story.
Let me explain. The Fire Hydrant assm. that we all see is only part of the complete hydrant. The surface component usally has three hose connections. There also a fixture for a wrench type tool that is put on and turned. As the wrench turns it opens the other part of the hydrant below ground and the water is released to the connections located on the sides of the Hydrant that we all see. It really operates much like the water faucet located on the outter wall of most houses. You connect your hose turn the handwheel and away you go.
As for the scenes we are all familar with were the car hits a hydrant and the water gushes out, It can happen if the impact hits in a certain way in which the below ground section is damaged or caused to burst. They now have hydrants with a breakaway feature just to prevent such happenings. The Hydrant, when struck, breaks away and damage to the underground components is kept to a minimum. They even have a repair item called, “A collision repair kit”.
Also the Industry standard depth is 3′6″ for most Hydrant applications. Hope this is of some help.
I’ve actually never seen a fire hydrant “in action” So thank you for the movie trivia on how they actually work. I always guess that the water was not stored in the hydrant.
for the most part dry barrel fire hydrants are used in cold climates.
due to cost most cities like hollywood calif uses wet barrel hydrants because it rarely freezes in the LA CALIF area. and you never have hard freezes.
due to the cost of dry barrel hydrants (about 3 time more then dry hydrant) most cities that don’t need them don’t use them.
it is common for the news to show water gushes up hundreds of feet in the LA Calif area after a hydrant is hit.
that is what the movie people in Hollywood see on the news.
give it a few years and global warming will let it happen in more of the country.
Calif is the biggest user of wet barrel fire hydrants
definitely seen water gushing out of the fire hydrants here in SoCal, not hundreds of feet, but 20-30 feet is pretty common. (no freezing here) The water is not “stored” in the hydrant but is under pressure from gravity and the hydrant is the “plug”, the same as the residential water supply.
Cool, good post
omg u are so arrogant its funny =D =D
actually there are hydrants that have water on the inside those are in areas where the water underneath wont freeze is called a wet hydrant. thats in places like Los Angeles
Hmmm that is interesting. As to the person who said that their fire hydrant is gushing, the guy didn’t say all fire hydrants have no water stored there he just said most store the water bellow ground. My thoughts are that in areas where they don’t have to worry about freezing tempuratures they might not store the water bellow ground. Or something could be wrong with the plumbing of the area. Just a guess though.
I have to guess that there is a plumbing system under the streets that go along with sewage. That’s my guess…
The water is stored underground but will come up if a fire hydrayant is hit. It just wont shoot up in the air. The fire truck just has a pump to put the water pressure to a acceptable psi in order to fight fires. I mean think about it your house usually has 150 psi in water pressure would that in a water hose fight a fire?? It might help a little but no it wont put a fire out any time soon.
Cool. Who knew? I always thought that hydrants were things that just sprayed water all over the street when there was a fire – I never realised that firefighters use them! Here in the UK, however, I have no idea how fire hydrants work…
if the valve gets damaged as the car hits it,,,,they will gush ,,,, it happened in our town they had to block the road until they got the water turned off
granted it wont gush all the time but if it gets hit just rite it will
if you don’t believe me call your fire /police dept ask them
In my neighborhood the hydrants are gushing but are controlled by a valve, the kids in the neighborhood sometimes hook sprinklers to it for fun. the hydrants here gush when you hit them but can be turned off using a secondary valve…
Green sleeves is right. in places like florida they would not waste the money to burie pipes deep beneath the ground. neither would they want to have to dig them up each and every time. altough the water is still underground the pipe may crack at a few feet down. this wouldn’t cause a geiser but if the pipe was cracked all the way around it would produce a geiser in some respect.
you said the water does’t shoot up like on tv when cars hit them well that’s not true cause my mother ,hit one and the water shot up so hard her car was stuck but when the water shot up it was so strong it moved her car off the fire hy. but you are right in away cause, i live right close to one and every so often they open the water and all it does is run down the road ,thanks debbie_ smith881@yahoo.com,,,,,,,,, what does ( URL)MEAN?
There are dry barrel and wet barrel hydrants. Areas likely to have freezing temperatures use dry barrel hydrants. Simply, these have a drain at the base of the barrel. Turning off the hydrant closes a seal at the bottom of the barrel and the remaining water drains away from the hydrant. Areas with warmer climates often still use wet barrel hydrants, though some also use dry barrel. In So. Cal. for example, you may still see a hydrant gusher if it is knocked over by a vehicle.
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Hey Mike,
I was wondering if “What is the meaning of Life” is an excaptable question on yahoo answers. I would love a disision in this matter because I personaly think that that is not all that knowlage worthy and I think that that should go in the same catagory as “Do you like my Avatar”
Shawn C.
Dim or a dog?! You do know that there are many places in the US that don’t have fire hydrants – mostly rural areas. You tried to be funny, but all you were was condescending and mean. Congrats.
Actually fixitcr63 fire hydrants are made it a break point on the arm, but you are right in the fact that water can spray up from a hydrant heres the actual reason why. There are 2 different types of fire hydrants dry barrel and wet barrel. Dry barrels are the ones where the water is stored underground and are mostly found whereever the temperature can drop below 28 degrees, and then there is also wet barrel which is where the water pressure is stored right in the hydrant you see along the road you will find these only in the southern part of the united states. If a wet barrel was hit and knocked off i gaurentee it will most definately squirt water 25-100ft depending on what kind of pressure is running to that hydrant. if you want to know anything else about firefighting or fire hydrants email me at utcdfcstat40@yahoo.com
I guess I’m showing how ancient I am, but one responder called them fire “plugs”. Why were they called plugs?
In the days before fire “plugs” the fire fighters accessed what ever water supply was available; ponds, rivers, wells, etc…..
In the 19th century (I need someone to correct me if I’m wrong on the era) and not long after cities started supplying water to buildings and residences one of the major cities suffered a horrendous fire that burned a major portion of the city. Sadly there were places where the firefighters had no access to water; they knew there was water in the underground pipes but had no way to get to it. After the fire and some thought the cities started to uncover some of the pipes (often just below the cobblestones), knocking a hole in the water pipe and hammering in a wooden “plug” so that the firefighters could have access to the city water supply. Thus the name “Fire Plug”.
i live in a cold weather state, upstate n.y., and we get freezing weather in the winter…..the hydrants sometimes freeze, making it difficult to draw water out of the hydrants to fight fires. in this case we need to call for mutual aid(extra tanker trucks) from neighboring fire departments to bring in water, then help shuttle water from fill sites to fire scenes.
i am waiting .. thanks for your help .. tcat alan rasool
They used to be called fire plugs for good reason. Firemen would dig to to water main (wooden)and then poke a hole in it to get water. Now the hydrant is opened with a 10-15 turn valve and upon closing the 10-15 turn valve the water is forced out of the vertical pipe through a “weep” hole connection to render the hydrant freeze proof. Anything to snap off these valves will indeed cause a column of water.
You’re still a douchebag.
There’s more than one way to skin a cat, or extinguish a fire…
Fire requires three things:
heat
fuel
oxygen
Attacking a fire through one of these avenues, brings flames to an end.
*water hoses seek to cool- fire goes out
*fuel tends to be consumed in the flames – fire goes out when fuel is used up and gone
*fire extinguishers (dry chemical, foam) block the oxygen from the fuel and flames.
I’ve seen fire hydrants burst here in socal. It actually happens.
Thanks for explaining that! Very informative.
As a firefighter in Southern California i can tell you YES by hitting a hydrant cause water to magically appear. I had a friend who ran one over in a Hummer , didnt feel it but the massive fountain looking thing behind her gave it away. You can also watch on the news and see that this happens. There are wet and dry hydrants but for the most part here at least you can create and a wet mess by hitting one.
Also not only in the olden days but to date we still access any water supply. Water is drafted from lakes, rivers, ocean, ponds, pools any where there is water…Well maybe not your toilet. You can also see this when the helicopters or planes scoop water and put a line around the fire or on hot spots…Just dont be underneath it when it happens, ya get a wee bit wet and could be knocked on your bum. Not to mention the fish and occasional scuba diver falling out of the sky LOL Just kidding
I didn’t know that much about hydrants before, but now I know a lot more! ;D
I’ve seen gushing fire hydrants that were hit by a car many times where I live in San Diego, California. The water is under the same pressure as the water that goes to our homes. Inside the fire hydrant, there is a shaft that goes from the nut at the top that turns on the water down to a plug that blocks the flow of water from the water main to the hydrant. When a fire fighter turns the nut with a special five-sided wrench, the shaft screws downward, creating a gap where it was previously sealed. This allows the water to go up to the hydrant, through a hose attached to the hydrant, and to the pumper truck. The truck pumps the water, greatly increasing the pressure and sends it to the fire. If a car hits the hydrant hard enought to break it off the pipe, the shaft that holds the plug also breaks, and the water rushes into the hole where the hydrant broke off. Since the water in the main is already under the same pressure as the whole water system, it can go pretty high up in the air. I’d say about 30 feet is usual. It usually creates a big lake in the road too.
When I visited Philidelphia back in the early 80s, kids would open the hydrant using a stolen wrench or some other tool, and play in the gushing water. During a heat wave, so much water was wasted, that the city had to pump water directly out of the river, and use a very strong chemical (Bromine I think) to purify it, that turned the color brownish. The city was pleading for people to leave the hydrants alone, but they didn’t. In New York, where this is a problem, the city puts a special sprinkler on the hydrant that doesn’t waste so much water and is a lot safer and more fun for the kids.
Mike, you’re brilliant and I admire you. It’s a gift from God. Do you believe in God?
ok well i have one thing to say.
DONT TRY TO PUT OUT YOUR OWN FIRES.
its called FIREMEN
they are there to help
YOULL KILL URSELF OR HURT URSELF if u try to put it out
so; FIREMEN
URL is Universal Resource Location http://en.wikipedia.org/wiki/URL
Not to get too techie, but firefighters make a distinction between “trucks” and “engines.” Fire engines are pumpers; fire trucks are for other duties. Trucks can be ladder trucks, rescue trucks, command trucks, etc. In NYC, for example, a fire house may have an engine company and/or a ladder company under the same roof, with two different companies of firefighters, each specializing around a truck or an engine.I assume that the same setup prevails in other large cities.
Water cannot leak from a hydrant sheared off at ground level due to a car crash. The construction of the valve seat and valve plug require that the valve plug be lowered away from the valve seat in order to allow water to enter the upper barrel of the hydrant. The construction of the valve stem, which pushes the valve plug down away from the seat, is held in place by the physical construction of the hydrant. The lower end of the valve stem has a “break-away” connection between the valve plug and the main, upper section of the valve stem. This break-away is weaker than the main stem and will hold the threaded end of the lower section of the stem in place to prevent the valve plug from moving away from the valve seat.
Another neat bit of history.
If you’ve ever heard of a fire hydrant refered to as a “fire plug” this comes from the early days of firefighting and water mains. Old city water mains used to be made of wood, and when firefighters would arrive on the scene of a fire, to get access the water, they would simply drill a hole directly into the wooden main.
After extinguishing the fire, they would then “fix” their hole by putting in a large dowel or “fire plug” into the water main. Hence, this is where the term fire plug came from, and hydrants are really not fire plugs, but some people refer to them as such.
lets not start name calling.
Actually, there are several different types of hydrants usually dictated by the climate. The kind you’re referring to is a dry stem hydrant and they’re used in locations that have harsh winters. If you’re in a warmer climate chances are you’ll have a wet stem, which can indeed be hit and spew water. Hydrants are actually attached to Engines, not trucks. Engines have a pump located inside the rig that applies pressure enabling hoses and other equipment to fight fires. Truck companies have large ladders and other equipment that are used to ventilate buildings that are on fire. Trucks and Engines work in tandem to put out the fire.
Did you also know that in the colder areas of the country, the valve that ultimately turns on the water is below the frost line to prevent freezing, hence no water if the hydrant is run over. That is not necessary in warmer climates so there will be gushing water since the valve is located in the hydrant.
Also, the pressure at the hydrant is rarely the same pressure in your home. Only class C hydrants can possibley have as low of a pressure as a residence. The hydrants must have a higher GPM (gallons per minute) to efficiently provide enough water for the pumpers. You can only pump as much water as what is in your tank. If the hydrant is only putting out 500 gpm, then the fire company is limited on their capabilities. They couldn’t save your house if a hydrant had the same pressure as your home. Hopefully a class A-C is on your corner. Class As have the highest gpm (up to 1500 gpm).
Fire fighting girls rock!!!
thanks
Fire hydrants are marked on the street by blue reflectors in the middle of the road, so they can be easily be found at night.
the hose we use to attach to the hydrant is called high volume hose (usually 4″ or 5″ in diameter). One end is attached to the hydrant and the other is attached to the argus(or intake of the pumper) After one flushes the hydrant first. then from there we take 150ft( 1″ 3/4 line) attack lines off the truck and stretch them out to the door. lines are charged from the pump panel and usually the pressure is around 100psi (700kpa) good enough pressure to put stuff out and still easy enough to move around corners. But that is what we run, and we have dry hydrants because when you are fighting fire at -40 with a windchill of -52 …can’t have the hydrant freeze on you.
Unless you’re either dim or a dog, you’re probably aware of the intended purpose of fire hydrants.
doesn’t this fall in with all the violations that we get hit for? or our questions deleted for the same sort of opening? Can someone please take 10 points away from Mike.
After reading some of the post there is one thing that was not mentioned and that is that in the northern part of the country an “anti-freeze” of some type is place in the top part of the hydrant to keep any seepage from freezing. At one time many years ago they used alcohol (1920’s-1930’s) so the first thing to hit the fire was the alcohol followed by the water.
Actually, depanding on where you live in the country will depend on whether you get wet if the car hits the hydrant. A dry hydrant (used anywhere the ground may freeze) has a butterfly valve down in the ground, keeping the water away from the top of the hydrant and preventing the water from freezing. As our friends from So. Cal. have pointed out a wet hydrant does not have this feature. The valve is right at the top of the hydrant allowing the water to sit at gorund level. If a wet hydrant gets hit by an auto, the valve will go with it and allow the free flowing of water pumped at whatever PSI the water company is flowing at. Normally this pressure is enough to get a pretty good fountian of water in the air.
San Francisco has two sets of fire hydrants, red ones charged with fresh water and blue ones charged with salt water from the bay. There are several large diesel powered pumping stations along the waterfront. The hydrants also seem to be quite a bit larger than average. A local landmark is Coit Tower (remember the movie “Dirty Harry’?) It is shaped like an old time fire hose nozzle.
actually Bob James in my experience with fighting fire i have found that there are four things involved in fires. and remove any one and they go out.
1. heat. thus water correct.
2. fuel. remove the fuel and fire goes out.
3. oxygen. remove the oxygen and fire goes. out. however not all fire extinguishers block the oxygen. some react with the chemical process itself and trap the free radicals thus interupting the chain reaction. for example pkp.
4. fire chiefs. get the chief out of the way and the fire goes out,
Mike,
The firefighters need those to put out fires.
and they don’t appreciate people parking in front of them.
Last December a restaurant got burned down
but while putting out the fire they had to use their hose hook it up
Several years ago a police car was parked in front of one.
It’s nice to know that a fire hydrant is nearby just in case.
Very few homes have the pressure or volume to put out a large fire so how can someone ask what fire hydrents are for.
Mike,
The Cornell article didn’t distinguish between wet-pipe and dry-pipe hydrants.
Dry-pipe are the type where no water is in the barrel, as it is stored underground in a pipe to prevent freezing (as you stated).
However, in many other places with a warmer climate (California for example), wet-pipe hydrants are used where the water is indeed stored in the barrel. These are the ones that create a geyser when knocked over (it’s not just Hollywood b.s.).
I gotta say, as an 18 year veteran paid “FIREFIGHTER”, that some people are WAY too touchy about the difference between Engines Trucks, Rescues, etc. How about focusing on the TOPIC, people!! The person was simply explaining the concept of a fire hydrant!! He is incorrect on one aspect and one only….that the hydrant never has water in the “barrel”. There are 2 types of fire hydrants, a wet barrel, and a dry barrel. The wet barrel is used when the temperatures fall below freezing, so there is a valve below street level that is operated by the “nut” on top of the hydrant. By turning it, you are turning a long threaded rod that is connected to this valve below. In warmer climates, such as California, there are “wet barrel” hydrants that have individual valves for each discharge opening. So if they’re struck by a car, they WILL spew forth a plethora of agua in a HURRY!! I hope that this helps some misunderstandings, and for the rest of you that get all bent out of shape about “firemen” “, “firetrucks”, “engines”, “pumpers”, etc…….LIGHTEN UP!!!! Jeeeez!!!
I always wondered what those valves on the fire trucks were for. I didn’t realize they were to regulate the fire pressure
There are both wet barrel and dry barrel hydrants. Wet barrel are cheaper and when sheared from the ground result in the hollywood fountian. Dry barrel hydrants are used anywhere they may be subject to freezing (ie most of the country except so-cal and miami). In those, the valve is at least 3 feet underground. When a car hits those…nothing really spectacular happens.
jess – those who put out fires prefer to be called ‘fireFIGHTERs’ as ‘firemen’ as the guys who shovel coal into the firebox of a steam locomotive.
Bob James – FYI there is also a fourth component of fire, the chemical reaction. There are chemicals that are used to fight fire that interupt the chemical reaction, thereby extinguishing the fire.
is agle
I have seen a “Hydrant Fountain” myself, and I am not from Hollywood! In addition to this, it is my first day being set up on “Answers”. After reading the comments on this (only), can anyone tell me if it is standard for everyone to be so nit-picky and for so many to come across as being superior to the next? If so I have come to the wrong place for sure!
Yeah an outlet of water which is mounted on a pressurized with couplings made to accept the fire hose couplings that are used by fire fighters, do not blame the hollywood straight away Mr. Mike ( I am an Indian and not a hollywood fan) as someone above said there are two types of hydrants namely Dry Barrel and Wet Barrel, the one you were discussing about is Dry Barrel commonly used at the regions where the temperature can reach to freezing levels) Wet Barrel is always filled with water and if hitted by a vehicle it can act as a fountain.
Interesting chapter since I am in Fire Protection bsns.