How a Fire Sprinkler Works at 100,000fps - The Slow Mo Guys
Gav and Dan like learning and like fast things. In this episode, they learn about a fast thing.
A fire sprinkler that you can probably see above your head if you are watching this from your office when you should be working. Shame on you! Nah, just kidding. Watch more Slow Mo Guys at work!
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Filmed at 1000fps with the Phantom Flex 4K and 103,000fps with the Phantom V2511
How a Fire Sprinkler Works at 100,000fps - The Slow Mo Guys

  • The Slow Mo Guys
    The Slow Mo Guys

    In the replies to this comment i'll be taking names for the possum.

    • my bogus
      my bogus


    • Boss Coins
      Boss Coins

      @Noxius ues

    • arozthebeast


    • DoctorX17


    • Will Bridge
      Will Bridge

      didcot county council

  • Zxilks YT
    Zxilks YT

    I knew how sprinklers worked before this but I just wanted to watch it in slowmo

  • Everything Jeepster
    Everything Jeepster

    They’re called freedom units.

  • Alan Johnstone
    Alan Johnstone

    the real deal has a lot more water pressure in the system. I know from my own experience in property management.

  • Phil Nolan
    Phil Nolan

    Time to call BS on every movie and tv program that shows all the sprinklers going off at once.

  • Jan Jančík
    Jan Jančík

    I liked how he flexed with his FLEX 4K. Flexing is *tight* !

  • happydoggs

    Would be cool to see one burst at the actual 200psi most fire systems are charged too.

  • FectacularSpail

    Who the heck are these 2.6k people who don't like this? Do they have something against possums?

  • Shadman Shahriar
    Shadman Shahriar

    Disappointed. Fire sprinkler doesn't sprinkle fire.

  • Pc Prosx100
    Pc Prosx100

    Also it’s not glycerin it’s mercury

  • Hans Johnson
    Hans Johnson

    So the way that these are normally deployed , the pipes are dry and pressurized with air at around 45 psi (3 bar). This air pressure is holding a valve closed that is holding back water at about 120psi (8 or 9 bar). The ampule breaks, releases the air out. At around 20psi, the flapper valve flies open, and the system fills with water at street pressure. They spray a lot further when they go off.

  • Filipi E.S
    Filipi E.S

    0:55 "155 American...things.'' almost spat out the food I was chewing lmao

  • Zeta Alpha
    Zeta Alpha

    We all say Fahrenheit but we all mean ‘american’

  • Hotelogence Gaming
    Hotelogence Gaming

    Gav. Possums aren’t cute. Reguards, Ian.

  • Hayden

    I thought I’d see a high-pressure one

  • A Random Youtuber
    A Random Youtuber

    Noob: it water garden! Pro: no it’s to put out fire. Noob: no it water garden! Pro and me: no! Now SHUT UP NOOB!

  • Egemen Artuk
    Egemen Artuk

    4:19 is what you came for. You are welcome

  • pixeley87


  • Elenesski

    HAHAHAHA ... you made my day with the line "155 american things" :)

  • Roofluffer

    needs more water pressure i think

  • stiffcookie

    Slow Mo Guys: "A fire sprinkler that you can probably see above your head if you are watching this from your office" Everyone: Looks up

  • Domingo Coralee
    Domingo Coralee

    The unusual crayon electrophoretically empty because okra morphometrically contain onto a shallow mimosa. ancient, common unshielded

  • Slice of Sparta
    Slice of Sparta

    Hello! Engineer for a company that makes sprinkley bois here! I loved the graphic that popped up at 0:52 about the colors and temperatures. The "glassy, juicy ampules" (lol Dan) are called bulbs, and like the graphic shows, the color indicates the burst temperature. Several factors determine what temp bulbs you want to install, the main one being height. For example, the sprinklers at the top of a warehouse need to burst at a lower temp because of how far away the fire is, compared with a standard residential or office ceiling height. Sprinklers can also activate via "links", which are basically little plate springs that are held at tension by solder paste. The fire melts the solder, the spring explodes outward, water comes out. The explosive quality of the bulb or link is important, because you have to get everything out of the way of the water flow. Some sprinklers, known as nozzles, don't have anything holding the water back! More on that in a minute! One last thing: if you're in a building with a flat ceiling and don't see any sprinklers, look for round discs instead. These are known as coverplates, and they provide an aesthetically pleasing way to cover a sprinkler from view! They can be color-matched to any ceiling, and like links, contain a solder paste that makes them pop off and expose the sprinkler at a much lower temperature than would actually trigger the sprinklers. Couple of myths: first one was one I used to think before working here is that the round bit on the sprinkler spins around as it goes off. Sadly not true for any sprinkler! That bit is called the deflector, and it's specifically designed to spread water in a certain pattern. Deflectors vary based on many factors, but primarily where the sprinkler is installed and the orientation in which it's installed. Many hotels use sidewall sprinklers with very different deflectors than the one in this video. Another big one: sprinklers always have water immediately behind them in their pipes, like Gav and Dan's in this video. Also not true! SOME systems are like that, and those are basic wet deluge systems. The problem with them is that it's relatively easy to have an accidental activation, which is the SECOND worst thing a sprinkler can do, because water from sprinklers can cause lots of damage, but not nearly as much as a fire. The worst thing is obviously if there IS a fire and the sprinkler doesn't activate. All sprinkler companies go through GREAT measures to make sure neither of these things ever happen! Back to water in the pipes: systems that do NOT constantly have water behind the sprinklers are known as dry systems, and they rely on a trigger mechanism to open the VALVE on the water main that holds back water to the system. The trigger is typically one of three things: an electronic signal from a fire/smoke detector, a wet pilot line, or a dry pilot line. Pilot lines are located with the sprinklers in the protection area, and are pressurized with either water or air (wet and dry). When the fire trips the pilot line, the pressure on the line goes away, which trips the valve to open and converts the dry system into a wet system, but only nozzle sprinklers go off at this point. Most wait until the bulb or link sprinklers trip. Obviously the pilot lines trigger at a lower temp than the sprinklers; that way the sprinklers always have water behind them when they trip. Some valves have multiple of these fail-safes, to further ensure against accidental activation! Any questions? I promise I can either answer you myself, or get a nice, smart coworker to help me out! Hope everyone is having a great day! 😊

  • Rachael Stickle
    Rachael Stickle

    sprinkly boys lol

  • Casey Locke
    Casey Locke

    Stay away from the possum. That's a nocturnal animal out in the daylight. Something's not right.

  • Tom Hensley
    Tom Hensley

    I beg yous pardon, it anit right talking bout us mercians. Got got it citrus fruit. Lol

  • KimShea22

    Lol, got a Koorsen ad right before this video

  • AfroAsia Adventure
    AfroAsia Adventure

    155 American things 😂😂😂😂😂😂😂😂😂😂😂😂😂😂

  • avinotion

    7:14 The last one was my favorite

  • Chris Scamdemic
    Chris Scamdemic

    That's nothing compared to a real sprinkler head going off on a real system. I'm a sprinkler fitter. I've seen it

  • waffl3_ir0n

    1 like = 1 pet for possum

  • AnglingNVirginia

    Really cool, except for him acting like a 5 Y/O little girl about some water..

  • MaxMeh

    Excellent Sir David Attenborough impression.

  • yousef diaa
    yousef diaa


  • Joshua Bennett
    Joshua Bennett

    One actually installed in a building has much more pressure and has a pump connected to it of pressure isn't high enough they actually cover much much much more then what it shows in the video

    • Joshua Bennett
      Joshua Bennett

      The most common system is a wet system where the pipes are full of water but there is also dry systems where the pipes are full of air untill the heads go off then they fill with water

    • Joshua Bennett
      Joshua Bennett

      There's also several different types of sprinkler heads and systems this head is called a pendant because it's upside down and ones that are upright are called upright heads

  • John Rosenthal
    John Rosenthal

    The mindless intestine histochemically guide because song remarkably park near a lonely macaroni. nine, flashy millisecond

  • D

    The flex 4K is $100,000. I guess he’s really “flexing” on us.

  • Nova Prime
    Nova Prime

    Celsius? I'm American i measure temperature in apple pies, 10 meters? You mean 15 dog tails.

  • Look See
    Look See

    Video starts at the 5 min mark

  • Aram Zero
    Aram Zero

    That glass could potentially hurt whoever is under that thing tho. Even just if it goes in the eyes!

  • Eween Mj
    Eween Mj

    These shots are making me thirsty

  • Nathaniel Walker
    Nathaniel Walker

    Imagine in 15 years when we can get this kind of slow motion on a phone.

  • Eric P
    Eric P

    "155 aMeRiCaN tHiNgS" Wow 😑

  • TheCrafter1952 Official
    TheCrafter1952 Official

    "One hundred... Fifty-Five... 'American Things'." Technically the truth!

  • maddoxXL101

    As someone who used to test these kinda sprinklers you obversions are very accurate as to how the over head sprinkler works lol

  • Chris Moore
    Chris Moore

    The bottom of the sprinkler is called the deflector and the bulb pops and the whole brass seat falls out. And no they all don’t go off like they do in the movies just where the fire is that sets the sprinkler head off. I’ve been installing them since 07.

  • DoctorX17

    Fun fact: this isn't the only design for sprinklers! There are some that aren't one time use, but this style is by far the most common. The only "flaw" is that you can, y'know, break the ampule with physical force, but that takes more than a slight bump. Usually something more like someone doing cartwheels and kicking it or something silly like that.


    2020!!! covid-19!




    u guys have cool camera's

  • Fahad Naqvi
    Fahad Naqvi

    Please make video on how much time eye takes in getting reaction when something sand type hits in eyes

  • MisterSoul2008

    Now you have the meadow full of broken glass.

  • Is Desert
    Is Desert

    life hack: set play speed to 0.25

  • Wing Man Au Yeung
    Wing Man Au Yeung

    Sprinkler head opens at 68 degree Celsius. Water pressure is needed to show the right spray pattern. Show intelligence, not dumbness


    Watching in 2160p 60fps

  • Timer Twinkler
    Timer Twinkler

    I just noticed higher fps means something is going slower then low fps.

  • Lord Matthew
    Lord Matthew

    Its like iv never seen a fire sprinkler before

  • James Perkins
    James Perkins

    Didn’t know there where opossums in the UK.

  • Michael Gentile
    Michael Gentile

    I thought the gear like thingy spun.. I'm kinda disappointed now..

  • Gh5rd5 Playzz
    Gh5rd5 Playzz

    5:16 is the ultimate crack of the red glass

  • Nixalin

    Aww yes American thing


    Anyone indian?❤️

  • K R
    K R

    4:21 ;)

  • Dakota Donna
    Dakota Donna

    Any other sprinkler fitters noticed he used a sprig up as a drop lmao 😂😂

  • TylerandMoRoll

    After watching your video of you adding the SFX / Foley sounds you add in these videos. I can't help but start to tune in on it more. And I gotta say. Adding those DEFINITELY makes these more aesthetically pleasing.

  • Benjamin Curley
    Benjamin Curley

    0:56-0:57 "american... uh- *things* " (10 seconds later) FARENHIET lol

  • kaden yeets
    kaden yeets

    Its at about 57 british things Celsius

  • Harry KelloTM
    Harry KelloTM

    American things

  • Jordan Quichocho
    Jordan Quichocho

    I only watched 2 vids and these guys had me subbed and notis on already,very funny and satisfying to watch

  • MaxDasNilpferd

    I saw this video 2months ago in my School Class.

  • 엑쥬페리갤러리


  • cptcrogge

    Won't this go off in case of an earthquake?

  • Dima G
    Dima G

    So there's glass shrapnel flying around and you two morons aren't behind plexiglass?

  • Jarett

    and i thought the gear lookin bit spun.

  • 최대니

    oh i saw a fire sprinkler as spitfire

  • Atomize

    “Money will come and go, we know that. But the most important thing in life will always be the people in this room, right here, right now”

  • Ghost of Me
    Ghost of Me

    Why is the background black with the 103,000 FPS?

  • Bronson Crawford
    Bronson Crawford

    The red stuff is mercury LMAO

  • KorisnikBr1

    Those Sprinklers are usually under 5 BARs of pressure

  • campanaro99

    That camera sounds like my pc when i play minecraft with a 64 chunk render distance

    • campanaro99

      @Kevin Davis LOL

    • Kevin Davis
      Kevin Davis

      n3rd al3rt

  • neal conn
    neal conn

    Should have done some lower K residential heads since they were using a gardening hose. Would have had a much larger wow factor

  • JKewgie

    Them: "You can see this at 103,000 frames per second!" Me, setting the video to .25 speed and getting 412,000fps: "Pathetic...."

    • Ben S
      Ben S

      ThAt’S nOt HoW iT wOrKs!!1!!1!1

  • Fredashay Klavierstein
    Fredashay Klavierstein

    0:50 We call them "Freedom Units."

  • Buck Jolicoeur
    Buck Jolicoeur

    1:48 I can see the "metal bit" flipping around.

  • Volt Vortex
    Volt Vortex Link to “We’re All Heroes in Slow Mo” by The Gregory Brothers This is the channel trailer for the Slow Mo Guys that is posted as “unlisted” for some reason, but it’s so awesome!

  • The Epic Gamerz
    The Epic Gamerz

    I never knew that 8k existed back in 2019.

  • Midas


  • EveryThingEverett


  • Raman Walsetwar
    Raman Walsetwar

    me lowering the speed to 0.25x and being so mo guys

  • Kallen Williams
    Kallen Williams


  • pmackni

    TIL: Me, working at an AEC firm (admittedly having nothing to do with Fire Protection other than collisions, as that's a separate discipline), had no idea sprinkler's glass bulbs were color coded. What they don't cover in the video, though, is that the water pressure for these systems is much higher than what you get with a garden hose. So actual operation is much closer to the initial burst we see until they're either shut off manually at the main valve (typical use case) or have run through their reservoir (if there is one, which depending on the building/facility, hazard level, at whatnot you'll likely rarely want it to stop on its own). Also, in order to limit the air in the system, since it's dry installed, they limit the water pressure by not fully opening the main valve until a little water comes out of the end of each branch of the system. After all, you don't want to have to wait for the water once they bulb bursts.


    Be honest guys. How many Australian you tubers are you subscribed to?

  • Southwest Fire Alarms
    Southwest Fire Alarms

    ah yes

  • Jim

    slo and educational. great job

  • Jack Gamboa
    Jack Gamboa

    I worked in a warehouse where someone hit a sprinkler head with his fork-lift. The first 983,645 gallons shot out in about 3 seconds and all of it was muddy brown with rusty water. The fire department had to come to turn it off, and the driver was sent out for a drug test XD


    I always thought it was a wax that broke and that the bottom part span around great video.

  • tunezjunkie87

    It's not Fahrenheit, it's Freedom Units. #murica

  • J Whitaker
    J Whitaker

    You guys know nothing of fire sprinklers, great attempt

  • thomas Burke
    thomas Burke

    Youz guys realize... sprinkler systems are like pressuized to 6 to 7 bar..

  • Ian Cipollini
    Ian Cipollini

    I want to see one go off at the actual pressure of between 100 and 300 PSI

The ASMR Bee Movie
1,1 milj.
The ASMR Bee Movie
1,1 milj.