Readded welder fuel.

Fixed issue with fire not generating light.
Fixed pre-merge issue with fuel passing through closed airlocks.

code/ZAS/Fire.dm

@@ -40,7 +40,7 @@ turf/simulated/hotspot_expose(exposed_temperature, exposed_volume, soh)
 	if(locate(/obj/fire) in src)
 		return 1
 	var/datum/gas/volatile_fuel/fuel = locate() in air_contents.trace_gases
-	var/obj/liquid_fuel/liquid = locate() in src
+	var/obj/effect/decal/cleanable/liquid_fuel/liquid = locate() in src
 	if(air_contents.calculate_firelevel(liquid) > vsc.IgnitionLevel && (fuel || liquid || air_contents.toxins > 0.5))
 		igniting = 1
 		if(air_contents.oxygen < 0.5)
@@ -63,7 +63,7 @@ obj
 		anchored = 1
 		mouse_opacity = 0
 
-		//luminosity = 3
+		luminosity = 3
 
 		icon = 'fire.dmi'
 		icon_state = "1"
@@ -90,7 +90,7 @@ obj
 						//Get whatever trace fuels are in the area
 						datum/gas/volatile_fuel/fuel = locate(/datum/gas/volatile_fuel/) in air_contents.trace_gases
 						//Also get liquid fuels on the ground.
-						obj/liquid_fuel/liquid = locate() in S
+						obj/effect/decal/cleanable/liquid_fuel/liquid = locate() in S
 
 					var/datum/gas_mixture/flow = air_contents.remove_ratio(0.25)
 					//The reason we're taking a part of the air instead of all of it is so that it doesn't jump to
@@ -177,67 +177,12 @@ obj
 
 			..()
 
-obj/liquid_fuel
-	//Liquid fuel is used for things that used to rely on volatile fuels or plasma being contained to a couple tiles.
-	icon = 'icons/effects/effects.dmi'
-	icon_state = "fuel"
-	layer = TURF_LAYER+0.2
-	anchored = 1
-	var/amount = 1 //Basically moles.
-
-	New(newLoc,amt=1)
-		src.amount = amt
-
-		//Be absorbed by any other liquid fuel in the tile.
-		for(var/obj/liquid_fuel/other in newLoc)
-			if(other != src)
-				other.amount += src.amount
-				spawn other.Spread()
-				del src
-
-		Spread()
-		. = ..()
-
-	proc/Spread()
-		//Allows liquid fuels to sometimes flow into other tiles.
-		if(amount < 0.5) return
-		var/turf/simulated/S = loc
-		if(!istype(S)) return
-		for(var/d in cardinal)
-			if(S.air_check_directions & d)
-				if(rand(25))
-					var/turf/simulated/O = get_step(src,d)
-					if(!locate(/obj/liquid_fuel) in O)
-						new/obj/liquid_fuel(O,amount*0.25)
-						amount *= 0.75
-
-	flamethrower_fuel
-		icon_state = "mustard"
-		anchored = 0
-		New(newLoc, amt = 1, d = 0)
-			dir = d //Setting this direction means you won't get torched by your own flamethrower.
-			. = ..()
-		Spread()
-			//The spread for flamethrower fuel is much more precise, to create a wide fire pattern.
-			if(amount < 0.1) return
-			var/turf/simulated/S = loc
-			if(!istype(S)) return
-
-			for(var/d in list(turn(dir,90),turn(dir,-90)))
-				if(S.air_check_directions & d)
-					var/turf/simulated/O = get_step(S,d)
-					new/obj/liquid_fuel/flamethrower_fuel(O,amount*0.25,d)
-					O.hotspot_expose((T20C*2) + 380,500) //Light flamethrower fuel on fire immediately.
-
-			amount *= 0.5
-
-
 turf/simulated/var/fire_protection = 0 //Protects newly extinguished tiles from being overrun again.
 turf/proc/apply_fire_protection()
 turf/simulated/apply_fire_protection()
 	fire_protection = world.time
 
-datum/gas_mixture/proc/zburn(obj/liquid_fuel/liquid)
+datum/gas_mixture/proc/zburn(obj/effect/decal/cleanable/liquid_fuel/liquid)
 	//This proc is similar to fire(), but uses a simple logarithm to calculate temp, and is thus more stable with ZAS.
 	if(temperature > PLASMA_MINIMUM_BURN_TEMPERATURE)
 		var
@@ -295,7 +240,7 @@ datum/gas_mixture/proc/zburn(obj/liquid_fuel/liquid)
 	return 0
 
 
-datum/gas_mixture/proc/calculate_firelevel(obj/liquid_fuel/liquid)
+datum/gas_mixture/proc/calculate_firelevel(obj/effect/decal/cleanable/liquid_fuel/liquid)
 		//Calculates the firelevel based on one equation instead of having to do this multiple times in different areas.
 	var
 		datum/gas/volatile_fuel/fuel = locate() in trace_gases

code/game/machinery/bots/cleanbot.dm

@@ -301,6 +301,7 @@ text("<A href='?src=\ref[src];operation=oddbutton'>[src.oddbutton ? "Yes" : "No"
 	target_types += /obj/effect/decal/cleanable/vomit
 	target_types += /obj/effect/decal/cleanable/robot_debris
 	target_types += /obj/effect/decal/cleanable/crayon
+	target_types += /obj/effect/decal/cleanable/liquid_fuel
 
 	if(src.blood)
 		target_types += /obj/effect/decal/cleanable/xenoblood/

code/game/objects/effects/decals/Cleanable/fuel.dm

@@ -0,0 +1,58 @@
+obj/effect/decal/cleanable/liquid_fuel
+	//Liquid fuel is used for things that used to rely on volatile fuels or plasma being contained to a couple tiles.
+	icon = 'icons/effects/effects.dmi'
+	icon_state = "fuel"
+	layer = TURF_LAYER+0.2
+	anchored = 1
+	var/amount = 1 //Basically moles.
+
+	New(newLoc,amt=1)
+		src.amount = amt
+
+		//Be absorbed by any other liquid fuel in the tile.
+		for(var/obj/effect/decal/cleanable/liquid_fuel/other in newLoc)
+			if(other != src)
+				other.amount += src.amount
+				spawn other.Spread()
+				del src
+
+		Spread()
+		. = ..()
+
+	proc/Spread()
+		//Allows liquid fuels to sometimes flow into other tiles.
+		if(amount < 0.5) return
+		var/turf/simulated/S = loc
+		if(!istype(S)) return
+		for(var/d in cardinal)
+			if(S.air_check_directions & d)
+				if(rand(25))
+					var/turf/simulated/O = get_step(src,d)
+					var/can_pass = 1
+					for (var/obj/machinery/door/airlock/door in O)
+						if (door.density)
+							can_pass = 0
+					if (can_pass)
+						if(!locate(/obj/effect/decal/cleanable/liquid_fuel) in O)
+							new/obj/effect/decal/cleanable/liquid_fuel(O,amount*0.25)
+							amount *= 0.75
+
+	flamethrower_fuel
+		icon_state = "mustard"
+		anchored = 0
+		New(newLoc, amt = 1, d = 0)
+			dir = d //Setting this direction means you won't get torched by your own flamethrower.
+			. = ..()
+		Spread()
+			//The spread for flamethrower fuel is much more precise, to create a wide fire pattern.
+			if(amount < 0.1) return
+			var/turf/simulated/S = loc
+			if(!istype(S)) return
+
+			for(var/d in list(turn(dir,90),turn(dir,-90)))
+				if(S.air_check_directions & d)
+					var/turf/simulated/O = get_step(S,d)
+					new/obj/effect/decal/cleanable/liquid_fuel/flamethrower_fuel(O,amount*0.25,d)
+					O.hotspot_expose((T20C*2) + 380,500) //Light flamethrower fuel on fire immediately.
+
+			amount *= 0.5

code/modules/reagents/Chemistry-Reagents.dm

@@ -993,25 +993,22 @@ datum
 			color = "#660000" // rgb: 102, 0, 0
 
 //Commenting this out as it's horribly broken. It's a neat effect though, so it might be worth making a new reagent (that is less common) with similar effects.	-Pete
-/*
+
 			reaction_obj(var/obj/O, var/volume)
 				src = null
 				var/turf/the_turf = get_turf(O)
 				if(!the_turf)
 					return //No sense trying to start a fire if you don't have a turf to set on fire. --NEO
-				var/datum/gas_mixture/napalm = new
+				 new/obj/effect/decal/cleanable/liquid_fuel(the_turf, volume)
-				var/datum/gas/volatile_fuel/fuel = new
+
-				fuel.moles = 15
-				napalm.trace_gases += fuel
-				the_turf.assume_air(napalm)
 			reaction_turf(var/turf/T, var/volume)
 				src = null
-				var/datum/gas_mixture/napalm = new
+
-				var/datum/gas/volatile_fuel/fuel = new
+				if(!T)
-				fuel.moles = 15
+					return //No sense trying to start a fire if you don't have a turf to set on fire. --NEO
-				napalm.trace_gases += fuel
+				new/obj/effect/decal/cleanable/liquid_fuel(T, volume)
-				T.assume_air(napalm)
+				return
-				return*/
+
 			on_mob_life(var/mob/living/M as mob)
 				if(!M) M = holder.my_atom
 				M.adjustToxLoss(1)