Whether accidentally or as an Improvised Weapon, the nozzle of a pressurized gas cylinder is easily broken off in fiction. When this happens, the canister will go shooting away like a rocket, blasting itself into the air and smashing through any thing (or anyone) unfortunate enough to be in its way. Sometimes this serves as an attack or a battering ram; occasionally, a reckless character will actually ride the thing.
Less credible, but still common, is a gas cylinder being ruptured by a gunshot and possibly shooting off like a missile. Whether this results in a Gas Cylinder Rocket or merely Stuff Blowing Up generally depends on whether the target it's being used against is right next to it or somewhere up ahead.
Both variations are partially Truth in Television. The valve is the most fragile component of a pressurized gas cylinder, and the gas inside does store more than enough energy to hurl the cylinder around the room. For just this reason, gas cylinders are supposed to have a protective cap screwed over the valve at all times when not actually in use. However, breaking the valve isn't exactly easy, and punching a hole in the cylinder itself is much, much harder. A gunshot may not even make a dent (depending, of course, on the tank, the gun, and the round).
Sister trope to Aerosol Flamethrower. Subtrope of Improvised Weapon and Explosive Propulsion. Compare Recoil Boost, which uses More Dakka for propulsion instead of compressed gas. See also Exploding Barrels, for when the "rocket" part is absent.
- Not actually a gas cylinder, but a similar effect occurs in The Croods when the grandmother, attempting to beat the fire that's burning the end of her staff to death against the ground, sets some giant corncob-like plants alight. The flames heat up their oversized kernels until they pop, sending the cobs streaking in all directions; the "rocket" analogy is taken even further when the ones that fly upwards explode into colorful sparks, like fireworks.
- In Bolt, a gas canister at the animal shelter is damaged and goes shooting into the parking lot, where it knocks down an illuminated sign that topples onto a car, resulting in a huge explosion.
Esther: Sweet Sister Frances! What did you do to my new truck?!
Martin (runs right in): HOLD ON RIGHT THERE!
(Startled, Esther pepper sprays Martin, who falls to the floor in pain)
Martin: AAH! GOLLY, ESTHER! (moans in pain)
Esther: Both you boys need serious help!
Martin: SPICY EYES!
- In Rio, Blu attaches Nigel's leg to a fire extinguisher, then sets it off. The evil cockatoo is dragged from the plane by the rocketing canister.
- In Over the Hedge, a broken propane tank sends a grill skyward, even flying over an airplane.
- In Incredibles 2, Helen shoots the oxygen tanks Evelyn has on her back with a flare gun, causing them to blast off like a jet pack.
- In Freddy vs. Jason, Freddy launches a series of scuba tanks at Jason when they're battling at the abandoned Camp Crystal Lake.
- Bronson in Street Trash is killed when a gas cylinder is send flying his way, and it removes his head.
- There is a literal variation in SpaceCamp that is definitely not Played for Laughs. After Andie is successful in supplying the space shuttle Atlantis with an extra supply of oxygen, she forgets to turn off the oxygen tank when she takes the hose off, which results in the oxygen tank rocketing backwards with her holding on to it, until she gets knocked unconscious from running into the side of the ship.
- Likewise in Gravity. A fire breaks out on the International Space Station, and when Ryan Stone tries to extinguish it the thrust of the extinguisher slams her against the bulkhead, knocking her unconscious for a moment. This becomes a Chekhov's Gun when she later uses the extinguisher to maneuver herself to another space station.
- In Jumanji, Peter creates a rocket sled in a sporting goods store by strapping two scuba tanks to a canoe, and then breaking the ends off by dropping a barbell on them.
- In Chain Reaction, Eddie chops the valve off a tank of hydrogen gas to shove open a safety door so he and Dr. Sinclair can escape.
- In Scooby-Doo 2: Monsters Unleashed, Scooby uses a fire extinguisher to freeze a monster and then ride it around on the frozen monster like a snowboard. He then kicks off the end of the extinguisher and rides it briefly like a rocket.
- Averted in Jaws, when the gas canister merely explodes rather than takes off (but see Mythbusters example below).
- An unlucky victim in Final Destination 4 is struck by one of these and slammed into a chain-link fence with enough force to turn his back into chunks.
- In Transporter 2, Frank pushes a hospital cart with a gas cylinder on it into Lola's path, then throws a chemical carboy into the light fixture above it. The collapse of the fixture knocks the nozzle off the cylinder and sets its gas on fire, causing it to shoot down the hallway and blow up right next to Lola.
- In 3 Ninjas: High Noon On Mega Mountain, the boys try to dispose of a time bomb by strapping it to three oxygen tanks and then breaking the nozzles off with a hammer. However, they turn out to not be strong enough to break them. Fortunately, Dave Dragon shows up and is strong enough to break them. For bonus points, the bomb gets propelled to the escaping bad guys' boat just as the timer hits zero.
- Played for Laughs in the 2000 New Zealand comedy film Savage Honeymoon. The main characters get drunk on whisky, and one of them throws an LPG (propane) cylinder on a bonfire, causing it to shoot in the air like a firework. This scene was notable for causing trouble with the New Zealand film censors, where a compromise was eventually reached by certifying the film with an R15 sticker.
- In the Syfy Channel Original Movie Dam Sharks!, the heroes launch a couple of gas cylinders into the shark-built corpse dam by chopping off their nozzles with axes. The cylinders blast off and streak through the air to lodge themselves in the dam, yet somehow still have enough pressure left to explode and destroy it.
- In the similarly-stupid Atomic Shark, the two heroes use SCUBA gas cylinders to propel their boat safely out of range of the mini-nuclear blast that's set off when the title creature finally dies.
Jamie: It was the lard that did it.
- The group tested this one, and confirmed that a large gas cylinder under sufficient pressure could smash its way through a concrete wall (!), although it slid across the floor rather than taking off and flying.
- They also got this effect accidentally when they simulated the ending to Jaws. Rupturing the gas cylinder didn't cause it to explode, but it did blow backwards with sufficient force to tear their foam-latex shark head to pieces and deform the shipping container they were using as a bunker.
- Subverted when they tested an Urban Legend about a propane tank that blasted off like a rocket, as every attempt to rupture or ignite one either failed or blew it to pieces.
- In an episode of Stargate Atlantis Ronon tried to use an oxygen tank rocket to break down a sealed door, having gotten the idea from watching Jaws. It didn't work.
- An episode of Sliders ("The Exodus", part 2) had Quinn and company locked in a room as the evil Rickman was sliding without them. They used an oxygen tank attached to a rolling metal hospital tray as a rocket to bust the door open.
- Due South: In 'Mountie on the Bounty', Fraser and Ray K use ruptured air tanks as rocket packs to escape the sinking ship.
- On CSI, a canister of nitrous is ruptured by a stray bullet during a shooting at a rave. The canister lifts off, trailing sparks, and flies erratically back and forth before slamming down among the party-goers, injuring several who were too high to get out of the way.
- Turned up a few times in London's Burning, usually played somewhat more realistically in that the source of the explosion was the building or vehicle the cylinders were stored in being on fire, which is easily the most reliable way of getting this effect in real life. The seventh season ended with a particularly memorable example after a fire broke out in a builder's yard behind a row of terraced houses, with about fifty of them shooting off like bottle rockets and crashing down all around whilst Blue Watch tried frantically to evacuate the local residents and get the fire under control. We find out in the first episode of the next season that the fire eventually took three days and fifteen crews to bring under control, with one fire truck burnt out after it took a direct hit.
- MacGyver (1985): In "The Odd Triple", Mac is locked up in the cellar of a winery. Needing to escape, he attaches several oxygen tanks to a large wheeled wine cask. Knocking the heads off the cylinders, he turns them into juryrigged rockets that propel the cask through the wall like a battering ram.
- On Z Nation, Doc mercies two zombie asylum inmates by knocking the hose off a wheelchair-bound zombie's oxygen tank, then sticking the hose's end into a broken light fixture. The electrical shock from the light travels to the canister, setting the zombie on fire. The fire then ruptures a second tank containing fuel for the wheelchair, causing a jet of flaming fuel that propels the wheelchair, its occupant, and another zombie standing behind it several yards down the hallway before both tanks explode.
- In the casual hidden object game Surface: Mystery of Another World, you can use a Gas Cylinder Rocket to propel a large statue out of your path.
- You can do this in Just Cause 2; it's even possible to ride the canister.
- In Max Payne, gas cylinders typically behave like that when someone shoots them. It's entirely possible to ride on them for the fun factor by standing on them before shooting at them, although there are only a few short, room-size "routes" possible.
- Valve Software's Source engine, used in every Valve game released in the 2000s starting with Half-Life 2, includes code to create a Gas Cylinder Rocket. The relevant reference material.
- In Halo, you can place these in Forge mode in games from Halo 3 onward (like Halo: Reach).
- In the Vivendi expansions of First Encounter Assault Recon, there are green gas cylinders that will fly about uncontrollably in unpredictable physics-oriented patterns when shot at or hit by an explosion... except they're completely harmless. All they really do is distract you with their antics (aside from the crazy flying, they make one hell of a lot of noise both before and during their explosion) and you alone, since the AI doesn't bat an eye at them.
- In a variation, the Trandoshan enemies in Star Wars: Republic Commando have jetpacks which send them shooting off into space when hit.
Scorch: I didn't know Trandoshans could fly!
- In Broforce, this is the only reliable way to deal damage to the Megacockter, by shooting the gas cylinders scattered around the rooftops causing them to fly up and explode on it.
- In Chapter 40-2 of We're Alive, Victor shoots a scuba tank that a Little One had become entangled with, sending the tank and Little One skidding across the street at high velocity.
- In the The Simpsons episode Mountain of Madness, a propane tank attached to a cabin gets its end knocked off and propels the structure downhill:
Homer: [praying] Dear Lord, protect this rocket house and all those who dwell within the rocket house.
- Instead of a gas canister, a malfunctioning surgical laser goes ballistic in the Roger Rabbit Short "Tummy Trouble".
- A very bad day on a Russian highway...
- Liquid nitrogen tanks have pressure relief valves for a reason, folks.
... the force of the explosion was directed upward and propelled the cylinder, sans bottom, through the concrete ceiling of the lab into the mechanical room above. It struck two 3 inch water mains and drove them and the electrical wiring above them into the concrete roof of the building, cracking it.
- There is a (possibly apocryphal) story floating around Caltech observatory staff that sometime in the late '80s a liquid nitrogen canister used for cooling the cameras at Palomar Observatory ruptured and flew across the observing floor, missing the telescope's mirror assembly by inches before punching out a door on the equipment bays. The practice of storing all compressed-gas canisters in the basement and only bringing small amounts of LN2 onto the observing floor at any one time in Caltech observatories is attributed to this incident.
- There's a welding safety poster floating around out there showing a mostly demolished building, with Those Two Guys standing around outside remarking, "Looks like Bob forgot to secure his oxygen canister again."
- One recurring image◊ often shown in safety briefs depicts the aftermath of a gas storage cylinder that blew out its base—namely, a neat hole punched in the ceiling, straight through a subsequent concrete floor, and into the room above it. Not visible: the utter state of disaster of the lab where the accident took place, because the cylinder blew out all the walls when it ruptured.
- Older pressure cookers were likely to carry out a variant of this trope should their steam vents have become blocked. After building up enough pressure, the resultant explosion would be enough to send the lid and much of the casing as shrapnel flying through the air with enough force to splinter countertops and leave dents in the ceiling.
- Note that in real life rocketry there is a type of rocket (pressurized gas rocket) that sounds like this trope but shouldn't be confused with it. Here, either the propellants or, more commonly, a neutral gas in a third thank are pressurized so that release of this pressure forces the propellants out the nozzle before its ignited. This is done to increase reliability and reduce mechanical complexity by eliminating pumps.
- However maneuvering thrusters powered by pressurized air sometimes used on small suborbital rockets, incidentally the same sort that tends to use the above. It's cheaper than using the alternatives like, engine trust vectoring, fly wheels, or monopropellant powered thrusters.