- "I kind of have a rapport with meta-humans."
- "You throw them in your pipeline prison."
- —Barry Allen and Oliver Queen[src]
The S.T.A.R. Labs particle accelerator, nicknamed The Pipeline, is a device that was created by S.T.A.R. Labs. Following its destruction, it was eventually used as a prison to house numerous meta-humans that it had created. Eobard Thawne also used it as a backup hideout.
On the night of December 11, 2013, the particle accelerator was activated by S.T.A.R. Labs to power all of Central City with clean energy, and to further the advancement of the science and medicine; however, when they turned it on, something went horribly wrong, and the particle accelerator exploded, sending a huge shock-wave into the clouds and through the entire city. It also created a lightning storm above the Central City Police Department, electrocuting Barry Allen and sending him in to a coma. This incident caused him to get the ability of super speed. The incident also supposedly caused the deaths of seventeen people and injured countless others. According to Clifford DeVoe, 2600 people developed the meta gene as a result. By co-incidence, the "mistake" "Wells" made on Earth One was the same mistake the Earth Two Wells made on his accelerator.
Repurposing the accelerator
Eventually, after Barry Allen's team concluded that they couldn't keep killing meta-humans, they realized that the cavities in the particle accelerator's core chamber could contain the meta-humans' powers, and converted it into a makeshift meta-human prison. Each cavity uses a 8.3 tesla super conducting electromagnet on its barrier which makes the seal 100,000 times stronger than Earth's magnetic field, which means that it can hold meta-humans with super strength, although a Time Wraith was shown to be strong enough to nearly shatter the glass door of one of the cells.
Tony Woodward was imprisoned after being defeated by Barry as well. He was released by Dr. Wells shortly after his initial imprisonment to combat Farooq Gibran when he broke into S.T.A.R. Labs to find Wells. Gibran killed Woodward, but after Gibran himself was killed, his corpse was put into a cell, where Wells extracted some of his blood to find out how he took Barry's powers.
Hartley Rathaway was briefly imprisoned here before breaking out.  To make up for allowing Hartley to escape, Cisco specially modified Shawna Baez's cell with mirrored glass to prevent her from teleporting out of it. However, after Barry changed the timeline, Hartley never escaped the Pipeline, and instead became an ally to Team Flash after Caitlin and Cisco hid inside his cell to prevent a Time Wraith from getting to them.
After he traveled back in time to stop Mark Mardon's tidal wave from destroying Central City, Barry used his knowledge of future events to find Mardon and imprison him in the Pipeline before he could do any real damage.
After impersonating many people and causing terror in Central City, Hannibal Bates was defeated by Barry and imprisoned in the Pipeline. However, he was freed by Eobard in exchange for impersonating him in order to set up Barry Allen's team, knowing he'd be killed. Following his kidnapping of Eddie Thawne, Eobard took him to a secret lair he'd set up underneath the Pipeline.
Eobard later had Grodd release a mind-controlled Wade Eiling on Central City. After Barry defeated him, the general went into a vegetative state and was locked up in the particle accelerator. However, after Grodd was defeated, the team released Eiling. That evening, Eobard left his lair underneath the accelerator and entered the Pipeline, turning it on with the "key" he had created in his lair.
The team soon realized that Eobard had slowly been rebuilding the Pipeline and hiding underneath it. He left his hideout, freeing Peek-a-Boo from her cell as he did so. The team managed to recapture Shawna and after they put her back in her cell, they also found Eddie. When they took him back up to the Cortex, they realized that Eobard was going to turn on the Pipeline again.
The team debated what to do with the imprisoned metas, as Barry didn't want to let them die when the Pipeline was reactivated. They decided to move the metas to Lian Yu and bring them to Ferris Air in a truck modified to block out their powers. Barry negotiated with Leonard Snart and his sister Lisa Snart to provide protection, and the two agreed. The team sedated the metas by spraying knockout gas into their cells, and placed them in a Ramon Shipping truck.
The metas awoke and began squabbling, with Mark Mardon in particular picking a fight with Kyle Nimbus. However the Snarts sabotaged the truck, and the metas escaped, with Mardon striking down the plane meant to take the metas to Lian Yu with a lightning bolt. In the ensuing battle, the metas battled with The Flash and his team; Simmons was seemingly killed when being shot by Leonard's Cold Gun, Nimbus and Shawna fled the scene, while Leonard recruited Mardon and Bivolo to the Rogues.
That evening, Eobard returned to S.T.A.R. Labs, but was "defeated" by the combined efforts of Barry, the Arrow, and Firestorm, and placed in a cell in the Pipeline, all only because he let himself lose because he wanted back into the Pipeline.
Eobard was placed inside the Pipeline. Barry often visited Eobard to get answers about his mother's death, and Eobard told him that he could go back in time to save his mother. Eobard explained that his plan required using the particle accelerator, explaining that Barry would have to run at Mach-2 speed through the accelerator and collide with a hydrogen particle. Doing so would allow Barry to travel back in time and create a wormhole through which Eobard could return to his own time. Cisco later visited Eobard in his cell, and Eobard explained to him that he was a meta. Eventually the plan came to fruition and Barry ran at the speed required, making the jump and opening the wormhole. Eobard attempted to return to his own time in the Time Sphere, but a strange helmet came through the portal, followed by Barry, who destroyed the Sphere. Barry and Eobard fought, but Eddie Thawne shot himself and died, also erasing Eobard from existence. The portal closed but then re-emerged above Central City, although Team Flash managed to close it, thanks to the combined efforts of Barry and Firestorm.
Reuse as a prison
After Iron Heights Prison opened a meta-human wing, Team Flash no longer used the accelerator as a prison. However, after Barry and Firestorm defeated Henry Hewitt he was incarcerated in the Pipeline until he agreed to keep quiet about what he'd seen and done.
Following Barry's defeat of Dr. Light, she was incarcerated in the Pipeline to be used as bait to lure Zoom to Earth Two. However, Dr. Light subsequently made herself invisible and escaped the Pipeline, likely due to fear for her own safety from Zoom. 
Russell Glosson was defeated by the Flash and was incarcerated in the Pipeline so that the team could use his powers to potentially find a way to slow down and stop Zoom. Afterwards, however, Harry Wells injected Glosson with a drill-like device to obtain a sample of his brain tissue, killing him. 
When a younger version of the Reverse-Flash arrived in 2016, Barry managed to overpower him and imprison him in the Pipeline. While imprisoned, Barry learns why Eobard hates him so much enough to kill his mother, and Cisco gloats that his powers were what led to his imprisonment. However, Eobard's capture resulted in a rupture in the timeline that threatened to kill Cisco, so the team was forced to help Reverse-Flash return to the future. Both speedsters raced around the Pipeline in parallel until a wormhole opened up for Eobard to pass through.
After the team found out that Harry was secretly working to steal Barry's speed for Zoom, Joe West angrily threw him into a cell to prevent himself from killing Harry. However, the team decided to release him and head to Earth Two to rescue his daughter, Jesse. 
When Trajectory raided S.T.A.R. Labs to obtain more Velocity-9, she threw Barry into a cell to prevent him from interfering with her plans. Once she obtained the drug and escaped, Cisco released Barry to chase her. 
Following the revelation of Zoom's identity, Barry decides to travel back in time to his first encounter with Hartley Rathaway to get Eobard Thawne to teach him to get faster, and raced around the Pipeline until he created a wormhole. However, his objective became complicated when he arrived earlier than expected and a Time Wraith pursued him. After acquiring what he needed from Thawne, Barry raced around the Pipeline to return to his time, but the Time Wraith attempted to catch him. Thankfully, his younger self is able to stall the Wraith long enough for future Barry to escape.
Second particle accelerator explosion
After Barry surrendered his speed to Zoom, Harry suggested creating another particle accelerator explosion to restore his speed. Having studied Eobard's data from the first explosion, Harry was confident that he could contain the dark matter explosion to S.T.A.R. Labs. Though hesitant, Barry only consented when Zoom began a reign of terror on Earth One. Recreating the circumstances, Harry injected Barry with the chemicals from his (Barry's) lab, while Cisco used the Wizard's Wand to create a lightning storm. When Barry was struck by the lightning bolt, he was transported into the Speed Force, while the dark matter flooded through the hallways of the building, hitting Jesse Wells and Wally West, who had left the protection of the Time Vault.
After the team were able to stop Zoom's meta-human army, a few of the meta-humans were taken to the Pipeline rather than sent to Iron Heights; as one of these prisoners was Laurel Lance/Black Siren, the double of the team's late ally Laurel Lance/Black Canary, it is likely that the other prisoners confined in this manner were also those who had counterparts on Earth One.
Team Flash also continues to occasionally use the Pipeline as a prison, using it hold particularly dangerous individuals, such as Earth-X Tommy Merlyn.
Team Flash also uses the prison as storage for meta human tech, as Joslyn Jackam's staff was put in one of the prison's cells. Its likely that other villains' equipment has also been stored in the pipeline.
In 2016, the Pipeline was used by Barry to help train Jesse Wells in the use of her powers. While performing a leap, Jesse accidentally tripped as her foot hit the catwalk and tumbled uncontrollably before getting her feet back on solid ground, and exited the Pipeline.
As part of his quest to seek revenge against Oliver Queen and the rest of Team Arrow, the vigilante known as Prometheus broke into S.T.A.R. Labs and freed Black Siren from her cell without anyone noticing.
When new meta-human Becky Sharpe used her power of quantum manipulation to give herself good luck while causing an escalating amount of bad luck to those around her, the escalating bad luck reached such heights that the particle accelerator briefly reactivated. However, the field it generated made contact with and cancelled out Becky's quantum manipulation field, as the charge released from a hydrogen-electron collision neutralized the field long enough for the team to take her into custody.
After a strange lightning storm struck, (appearing and disappearing all in a few minutes) Nora, Iris, and Barry went to Iron Heights to ensure that Mark Mardon/Weather Wizard was still in prison where he should be. It turned out that the lightning storm had disabled the meta-dampeners in Iron Heights, although the prison staff were able to get all the meta-human inmates into power-dampening cuffs without problems. However, a woman named Joslyn Jackam, who appeared to have weather-powers like Mark's appeared, saying that she was there for Mardon, and that he was her father. Barry then changed into his Flash suit, sped Weather Wizard to S.T.A.R. Labs and put him in the pipeline. After Joslyn Jackam was defeated and taken into custody, Mark was locked in Iron Heights again. At the same time, Team Flash stored meta-tech like Joslyn's staff in the Pipeline until they could figure out how to remove the dark matter shards.
After Mar Novu/The Monitor used the Book of Destiny to alter reality, causing Barry Allen/The Flash and Oliver Queen/The Green Arrow to switch lives (with them being the only ones who knew things had changed), when Team Flash refused to believe them, they cuffed the duo and stuck them in a cell in the Pipeline while the group tried to figure out what was going on with them, believing them to be crazy. Ultimately, "Oliver" (Barry) suggested the two of them go to Earth Thirty-Eight to find out if Kara could still tell that Barry was Barry, and Oliver was Oliver. "Barry" (Oliver) then began complaining that the cells in the Pipeline lacked toilets, with "Oliver" (Barry) revealing one hidden inside the wall of the cell. "Barry" (Oliver) then walked "Oliver" (Barry) through how to take his thumb out of its socket to get his hand free of the cuffs in order to back up the pipes and disable the cell's meta-dampeners. "Barry" (Oliver) was then able to phase them both out of the cell. After that, they persuaded Iris to let them use an interdimensional extrapolator to go to Earth Thirty-Eight to talk to Kara.
In another alternate reality created by the Book of Destiny, Kara was locked in the pipeline and Alex's Earth One counterpart was tasked with looking after her. Alex took some convincing, but ultimately, Kara persuaded Earth One Alex to let her out.
According to Eobard Thawne, in the supposed timeline that he hails from, Harrison Wells and Tess Morgan launched successfully the S.T.A.R. Labs particle accelerator in 2020, in which supposedly gave Barry Allen his connection with the Speed Force. However, because Eobard killed Wells and Tess in 2000, these events have been changed to reflect the current timeline.
Known victims of particle accelerator's first explosion
- Barry Allen/The Flash/Savitar (later lost his powers and recreated a smaller explosion to regain them with the aid of his friends)
- Shawna Baez/Peek-a-Boo
- Hannibal Bates/Everyman (deceased)
- Roy Bivolo/Rainbow Raider
- Danton Black/Multiplex (deceased)
- Clifford DeVoe/The Thinker (deceased)
- Rosa Dillon/Top
- Dinah Drake/Black Canary
- Adam Fells/Geomancer
- Farooq Gibran/Blackout (deceased)
- Russell Glosson/The Turtle (deceased)
- Griffin Grey (deceased)
- Jefferson "Jax" Jackson/Firestorm (powers triggered by the Firestorm Matrix; later neutralized by a cure created by Cisco Ramon and Harry Wells)
- Leslie Jocoy/Amunet Black
- Henry Hewitt/Tokamak (powers triggered by the Firestorm Matrix)
- Martin Stein/Firestorm (powers later neutralized by a cure created by Cisco Ramon and Harry Wells; deceased)
- Clyde Mardon (deceased)
- Mark Mardon/Weather Wizard
- Joseph Monteleone/Tar Pit
- Kyle Nimbus/The Mist
- Cisco Ramon/Vibe
- Ronnie Raymond/Firestorm (deceased)
- Sam Scudder/Mirror Master
- Bette Sans Souci/Plastique (deceased)
- Vincent Sobel/Vigilante (deceased)
- Sean Sonus (deceased)
- Jeremy Tell/Double Down
- Eric Frye (powers stolen by Melting Point)
- Tony Woodward/Girder (briefly re-animated as a 'zombie' by the second particle accelerator explosion; deceased again)
Non-canon victims of the particle accelerator's first explosion
- Nathan Bliss/Mr. Bliss
- Unnamed zoopathic woman
- Wangari Hollowell
- "Hydro Hunter"
- Shay Lamden/King Shark
- Song (deceased)
- Joey Rose
- Meta spiders
Known victims of the particle accelerator's second explosion
- Barry Allen/The Flash/Savitar (after losing his powers; got them back)
- Jesse Wells/Jesse Quick (from Earth Two)
- Tony Woodward/Girder (corpse temporarily re-animated to a zombie-like state by explosion, later killed again by Barry Allen)
- Abra Kadabra (released to be taken to Earth Nineteen to be executed; presumably deceased)
- Farooq Gibran/Blackout (killed prior to being stored in the pipeline as a corpse)
- Hannibal Bates/Everyman (released based on a deal with Eobard Thawne; killed in the process of fulfilling his end)
- Jake Simmons/Deathbolt (killed by Leonard Snart during relocation)
- Janet Petty/Null (powers absorbed by Clifford DeVoe, leaving her dead)
- Russell Glosson/The Turtle (killed by Harry Wells to obtain a sample of his brain tissue to learn how to use his powers to slow a speedster down)
- Tommy Merlyn/Prometheus (committed suicide by cyanide capsule)
- Tony Woodward/Girder (released and set loose as a distraction; killed in the process)
Chronicles of Cisco
DC's Legends of Tomorrow
The Flash: Season Zero
The Chronicles of Cisco
Behind the scenes
- The entrance to the particle accelerator's core chamber is marked as Entrance 52, a reference to DC's ongoing use of the number 52.
- The design on the particle accelerator's door looks similar to Firestorm's logo from the DC comics.
- In Eobard Thawne's timeline-of-origin, the particle accelerator opened in the year 2020 and its launch was successful.
- The accelerator shown is a cyclotron.
- In the Flash comics, "The Pipeline" is the maximum security wing of the Iron Heights Penitentiary, were the most dangerous and/or meta-human criminals are held.