Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Shurikane]

SITUATION
I created a large reservoir, into which I pumped magma.  The reservoir surrounds my magma pipe, so I dug into the side of it to speed up the process.  Because the magma spread quite quickly, I was only able to mine out one square on either side of the pipe.

The pipe drained at a very slow rate.  Once the reservoir was full, the pipe simply refilled itself back up to its former glory.

WHAT I'M TRYING TO DO
I want to purposely drain part of the pipe.  To do so, I will dig out its topmost layer, and funnel the magma elsewhere.  I will repeat the process for each layer on the way down.  The idea is to tear down part of the magma pipe, and turn it into usable areas for my dwarves.  Hopefully, I can go as far down as my magma reservoir, so that everything above can be used to the benefit of my fortress.

WHAT I'M NOT CERTAIN OF
I have a suspicion that the pipe will attempt to refill itself too quickly for me to be able to manage it, and that I'll simply end up with unsightly gutters that I can't condemn because of the magma flow.  I don't know how the game figures out how high a pipe is supposed to go.  Does it define a "refillable pipe" as what the embark started with, or does it eliminate parts if they get altered or destroyed?  I don't know, and I can't find an answer to this right now.

People experienced in pipes, what has been your experience?  Were you able to artificially decrease a magma pipe's content without necessarily the use of pumps?

[Bumber]

Does it define a "refillable pipe" as what the embark started with, or does it eliminate parts if they get altered or destroyed? I don't know, and I can't find an answer to this right now.

It's what the embark started with. I obsidianized the top of my pipe, and the parts that I channeled out refilled after a while. As far as I can tell, it spawns 7/7 units of magma randomly above other 7/7 units of magma in the pipe.

If you built floors/drawbridges over the pipe, you could block the flow. You'd need to drain the magma on the level below for safety.

[PatrikLundell]

I've been told the whole embark tile of a magma pipe is magma generating (which matches my experience), and it seems there is a "top level" associated with that tile, where new magma will spawn at that top level and rain down as far as it has to to top up a reservoir, provided there is a sufficient head room, i.e. unbroken direct vertical from the magma flow to that level  (I once had a pipe spilling its contents sideways out into the 3:rd cavern, with new magma being spawned about two levels above the surface, with evaporation keeping the whole thing in a steady state).
If there isn't enough enough head room, the spawning seems to take place at the highest available level (if you're obsidianizing the magma sea above such an embark tile, magma will spawn above the tiles you open and fall down to create a raising level where the rock used to be. Wet magma sea obsidianizing can push such a magma sea down with some semblance of safety).
I've also seem an indication spawned magma can "flow" sideways before falling (I did get magma on a ledge just outside a pipe's tile well above the current magma level beside it).

As far as I've seen, the magma spawn rain consists of 1/7 magma (in contrast to what Bumber has seen), so dry channeling down to the pipe magma sea will result in the tile slowly filling with magma, and spilling out to the side once 7/7 has been reached and the spawning results in lots of 1/7 on top of that.
Provided the pipe isn't broken (i.e. the walls go all the way to the top), building a floor above the pipe is perfectly safe from a magma point of view (magma crabs and the like doesn't make it completely safe though), as the spawning happens at the top level, not above.

The method below is pump based. I haven't done all of it, as the task I set myself was to drain the magma sea, but leaving the two pipes by themselves, by isolating those tiles. However, I did lower the level of a pipe a couple of levels with a single pump more or less by mistake a couple of times.

You CAN lower the level of a magma pipe by pumping away magma further down. The safe way to do that is to:
- Obsidianize the borders of the top level of the magma sea so that part of the sea is isolated from the map edge (ensuring all influx of new magma comes from the top of the pipe). If you have to, you can use wet obsidianization to isolate the map edge that's inside the pipe's tile. However, you'll want to place your screw pump array to take from outside the tile, to ensure you don't get magma spawning above the intake tiles.
- Build an array of (magma safe) screw pumps above the isolated magma sea so their input tiles are above the sea but outside of the pipe's tile. Build magma safe (not sure if that's required) track stops dumping away from the pumps on the screw pump output tiles and place magma safe mine carts on them (nether-cap is NOT magma safe for this applications, even though the pumps can be made out of it). Wall the whole mine cart-on-track stop area in so there's a wall behind each cart and complete walls to the sides of the array. You've now created a Portable Drain array behind the pumps. Hook the pumps up to power and channel out their input tiles. Wait while the pipe's magma level decreases.
- Obsidianize the pipe's new, stable, magma level by dropping water from above. I'd use mine carts to drop water in a ring from the edge inwards (as floors are built (far) above the obsidianized tiles, but running water can be used as well, but will result in a lot of cave-ins as water obsidianizes unsupported magma tiles.
- Once the magma pipe has gotten a new floor, you shouldn't get any magma spawning above that floor. Sideways flow in the air and other factors may cause the floor to be uneven. If you find that unsightly wet obsidianization should allow you to even it out.

Wet obsidianization: My term for flooding an area with 2-3/7 level of water and then channel down through the floor to expose the magma below. The water will immediately flow down into the hole and obsidianize the tile below, although over a magma pipe tile you occasionally get an obsidian block on top of the floor instead, presumably because a magma spawn happened to take place a the same time. Of this method is used outside of a magma pipe tile it will guarantee no magma critters will get up (I've had critters disappear from the unit list, which I think was due to obsidian encasement).
A couple of warnings:
- Make sure your miners aren't carrying babies (unless you want dispose of said babies). Wet obsidianization frequently causes the miners to drop babies, for some reason, and babies have been observed to drown.
- Wet obsidianization attempts above a magma flow tile carries a high risk of being lethal. The failure of the magma below the open floor to obsidianize results in a water current that frequently sucks the miner down.
- There is a risk for the miner to encase itself in obsidian. I think that is due to the miner being sucked down by the water current. This risk seems to be lower if the channeling is done such that the miner will have to move away from the channeled tile to get to the next one. This results in a fair bit of micro management, though. Multiple miners at work seems to increase the risk of them causing other miners to get sucked down. Note that the sucking is my guess as to what happens when a miner suddenly is just gone (when falling into magma they tend to stay alive sufficiently long for you to locate them).

And if you read the above you're ready to move on to quality literature, such as War and Peace.

[Loci]

Wet obsidianization: My term for flooding an area with 2-3/7 level of water and then channel down through the floor to expose the magma below. The water will immediately flow down into the hole and obsidianize the tile below, although over a magma pipe tile you occasionally get an obsidian block on top of the floor instead, presumably because a magma spawn happened to take place a the same time. Of this method is used outside of a magma pipe tile it will guarantee no magma critters will get up (I've had critters disappear from the unit list, which I think was due to obsidian encasement).
A couple of warnings:
- Make sure your miners aren't carrying babies (unless you want dispose of said babies). Wet obsidianization frequently causes the miners to drop babies, for some reason, and babies have been observed to drown.
- Wet obsidianization attempts above a magma flow tile carries a high risk of being lethal. The failure of the magma below the open floor to obsidianize results in a water current that frequently sucks the miner down.
- There is a risk for the miner to encase itself in obsidian. I think that is due to the miner being sucked down by the water current. This risk seems to be lower if the channeling is done such that the miner will have to move away from the channeled tile to get to the next one. This results in a fair bit of micro management, though. Multiple miners at work seems to increase the risk of them causing other miners to get sucked down.

If you dig downstairs instead of channeling the water will still fall but your dwarves cannot be washed down into the magma.

[PatrikLundell]

Wet obsidianization: My term for flooding an area with 2-3/7 level of water and then channel down through the floor to expose the magma below. The water will immediately flow down into the hole and obsidianize the tile below, although over a magma pipe tile you occasionally get an obsidian block on top of the floor instead, presumably because a magma spawn happened to take place a the same time. Of this method is used outside of a magma pipe tile it will guarantee no magma critters will get up (I've had critters disappear from the unit list, which I think was due to obsidian encasement).
A couple of warnings:
- Make sure your miners aren't carrying babies (unless you want dispose of said babies). Wet obsidianization frequently causes the miners to drop babies, for some reason, and babies have been observed to drown.
- Wet obsidianization attempts above a magma flow tile carries a high risk of being lethal. The failure of the magma below the open floor to obsidianize results in a water current that frequently sucks the miner down.
- There is a risk for the miner to encase itself in obsidian. I think that is due to the miner being sucked down by the water current. This risk seems to be lower if the channeling is done such that the miner will have to move away from the channeled tile to get to the next one. This results in a fair bit of micro management, though. Multiple miners at work seems to increase the risk of them causing other miners to get sucked down.

If you dig downstairs instead of channeling the water will still fall but your dwarves cannot be washed down into the magma.

It sounds like a great tip, and it if, provided channeling down on the down stair also bits into the obsidian underneath, rather than resulting in a topless tile being exposed. I've been bitten quite a few times by topless obsidian tiles resulting from a (built) up/down staircase a being removed after obsidianizing the magma flow tile below (I've learned the lesson and now remove the staircases before obsidianization).
Hm, even if it DOES result in topless tiles an Up staircase below should allow you to remove the obsidian by digging sideways out from the staircase, resulting in a bit more hassle, but still workable.

[Shurikane]

In light of this and other places I read the stuff about, I formulated a plan.

I will start by preparing a broad channel either side of the pipe, on several Z-levels.  These will all lead to a hole in which the magma can drop, into the reservoir.  I will create a staircase along the edge of the pipe, thereby giving the magma a way to escape, without putting any dwarves in harm's way.  The large channel should make it so the Z-level drains at a brisk pace, without a chance to refill.  Once that Z-level has emptied, I will repeat the process one level below, and so on and so forth.



Once the pipe has reached the desired height, I will plug a part of it, and leave a small hole in the middle.  Above, I will construct a cone.  From above, magma will come down (brought in by pumps, which feed in the reservoir) and bounce back into the reservoir instead of landing in the pipe.



At this point, the only worry is that the magma might not evaporate quickly enough for the dwarves to step down and continue digging.  If that happens, my plan is to build a few pumps, which will be hand-operated, and whose job will be to simply "push" the magma towards the holes I made off to the side.

[Salmeuk]

I have no idea if that will work, but post whatever happens anyways

[Dunamisdeos]

You could always drain it off the map.

[Shurikane]

You could always drain it off the map.

I prepared an overflow on my reservoir for just such an occasion. 

[PatrikLundell]

It's even easier to use Portable Drains than map edge drains.

The hole in the middle should cause magma to spawn above it at the inside top of the cone. As said earlier, it might be possible for the magma to "flow" sideways and end up on the rim of the hole. You'll also get magma rain on the dorfs building the part of the cone over the hole (unless that part of the cone is above the "natural" maximum top of magma in the pipe).