The 
Flamethrower is a Mekanism weapon that burns Hydrogen to shoot a stream of fire, which deals 10 damage with each flame and leaves whatever it hits burning for 5 seconds. It holds 24,000 mB of Hydrogen, and as it only uses 1 mB for every tick that you’re firing, a full tank is enough for 20 minutes of holding the button down.
It has three modes, which are Combat, Heat and Inferno, and they decide what the flames will do to blocks and dropped items. In Heat mode it’s even able to smelt blocks and items where they are, so it can be used as a tool as well as a weapon.
How to Get It
To craft the Flamethrower you’ll need 4 
Tin Ingots, 2 
Bronze Ingots, a 
Basic Chemical Tank, a 
Flint and Steel and an 
Advanced Control Circuit. The circuit is the part that puts it a step past the Jetpack, as it needs 
Infused Alloy on top of a 
Basic Control Circuit.
It comes out empty, so it has to be filled with Hydrogen before it’ll fire. That’s done in the same way as the 
Jetpack, by placing it in the item slot under the Hydrogen tank of an 
Electrolytic Separator, or in the top slot of a Chemical Tank with Hydrogen in it, where it fills at 16 mB a tick.
How to Use It
Firing It
Hold right-click with the Flamethrower in your hand and it’ll fire a flame every tick, each one flying for a few seconds at most before it burns out. A flame that reaches a mob deals 10 damage and sets it alight, although mobs can only be hurt every so often, so you won’t land all 20 hits in a second.
In Combat mode the flames destroy any dropped items that they hit as well, which includes the loot from a mob you’ve just killed. You’ll want to stop firing as soon as it dies, or the drops might be gone before you’re able to pick them up.
What It Won’t Hurt
Mobs that are immune to fire take no damage at all, which rules it out for Blazes, Magma Cubes and anything else from the Nether that doesn’t burn. The flames are also put out by any fluid that they touch, so it’s no use underwater or against something that’s standing in a river.
Flamethrower Modes
You’ll change mode by pressing the Item Mode Switch key while you’re holding the Flamethrower, which is N by default, or by sneaking and scrolling the mouse wheel. It starts in Combat, and a chat message will tell you which mode you’ve changed to.
| Mode | Mobs | Dropped Items | Blocks |
|---|---|---|---|
| Combat | 10 damage, set on fire | Destroyed | Left alone |
| Heat | 10 damage, set on fire | Smelted once they’ve been on the ground for 5 seconds | Smelted where they stand |
| Inferno | 10 damage, set on fire | Destroyed | Set on fire, and TNT is lit |
Mobs are treated the same way in all three, so the mode only changes what happens to the things around them. Combat is the one to leave it in when you’re near your base, as it won’t touch any blocks at all, whereas the other two will.
Heat Mode
Heat mode works like a 
Furnace that you point at things, as any block that has a smelting recipe is turned into its result when a flame hits it. 
Sand will become 
Glass in place, for example, whereas an ore block is broken and drops its ingot.
Dropped items are smelted in Heat mode as well, and a whole stack is done at once, as long as it’s been lying on the ground for 5 seconds. An item that has no smelting recipe is burned up instead, so keep the flames away from anything you’d like to keep.
Inferno Mode
Inferno doesn’t smelt anything, as it’ll start a fire where the flames land instead, burn up dropped items and set off any 
TNT that they touch. The block effects of Heat and Inferno depend on a setting in the Mekanism config, which is on by default, so a server might have turned them off. The 
Electric Bow is the mod’s other ranged weapon, and it runs on energy instead.
FAQ
It runs on Hydrogen, which you’ll make in an Electrolytic Separator, and it’s filled by placing it in the item slot under the Separator’s Hydrogen tank or in the top slot of a Chemical Tank that’s holding Hydrogen. A full 24,000 mB takes 75 seconds to go in, and it can’t be charged with power.
Each flame deals 10 damage, which is 5 hearts, and sets the target on fire for 5 seconds as well. It fires a flame every tick, but mobs have a short pause between hits, so the damage over time is lower than that would suggest, and fire-immune mobs take none.
Combat only hurts mobs and burns up dropped items, Heat smelts the blocks and dropped items that the flames hit, and Inferno lights fires on blocks, sets off TNT and burns dropped items too. You’ll switch between them with the Item Mode Switch key, which is N unless it’s been changed.
The mob is most likely immune to fire, like a Blaze or a Magma Cube, as those take nothing from the flames at all. Otherwise there might be Water or another fluid in the way, which puts each flame out when it touches it, or the tank has run out of Hydrogen.
