A flame thrower with a similar appearance to the ones used by the crew of the USCSS Nostromo was used aboard Sevastopol Station. The flame thrower had a capacity of 500 flamethrower fuel, the amount of fuel indicated by a gauge on top of the flamethrower.
In 2137, Amanda Ripley acquired a flame thrower from the Colonial Marshal Bureau aboard Sevastopol and carried it throughout the station to help her fend off the Sevastopol Alien, as well as other threats she encountered.
The flame thrower (along with the Molotov and Pipe Bomb) is one of the only weapons in the game that has any meaningful effect on the Alien. While it will not damage or kill the creature, a blast of fire from the flame thrower is usually enough to make it retreat into the station's ventilation system. However, a blast that's too short or from too far away will often not cause it to retreat, and the Alien will usually temporarily stand still to defend itself from the flames before slowly approaching the player. If the player is very close to the creature when they fire at it, the Alien will temporarily knock them down, damaging the player's health. If the player's health is very low and they are too close to the creature when they fire at it, the Alien will completely ignore and still kill the player.
Behind the Scenes
The flamethrower's design is clearly based on the Flame Throwerss built by Parker in Alien. Additionally, the weapon's front grip in Alien: Isolation is based on the laser pistols used in the film (which were actually built from Rexim-Favor submachine guns).