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[San-A]

I just read the wiki about the pump stack for magma and the frame drop.

This topic http://www.bay12forums.com/smf/index.php?topic=72296.0 seems to give a good alternative but I don't exactly understand the design. Did anyone try to draw it in 3D, a bit like in http://dwarffortresswiki.org/index.php/File:Jt_screwpump.png.

Also I have always wondered: once the magma has been pumped up and the output magma reservoir is full (just below the magma forge, if the aim is too forge and not to fill up the valley with magma), is it necessary to carry on pumping magma continuously? If there is no need pumping any more, then there is no more frame drop 

[Girlinhat]

The trouble isn't the pumps, it's the temperature updates.  If you have the area already covered in magma (ie, already "warm") and push magma through it, there's virtually no lag, just fluid movement.  Magma is such a killer because it's constantly re-updating all the different tiles for heat.

If you just want a quick forge setup, you can turn off temperature briefly.

[KodKod]

This image from the wiki page is a good example of what a pump stack looks like.



The only difference with the reduced lag magma pump is that instead of a single square carved out for the intake and output of each pump you use a 3x1, with the additional two squares carved out on either side of the original intake/output.

[San-A]

The only difference with the reduced lag magma pump is that instead of a single square carved out for the intake and output of each pump you use a 3x1, with the additional two squares carved out on either side of the original intake/output.

So if I understand well: only the in/out squares are affected my temperature updates, and if they are surrounded by magma then there is no need to recalculate. How about with a 2x1 carved out area instead of 3x1 (I'm sure the question has been asked...)

If the pump is switched off, is it still affected by this temperature re-calculation?

Thanks for the enlightenment

[KodKod]

Appropriate quotation of my own knowledge of the subject:

"I'll tell you the problem with the scientific power you're using here: it didn't require any discipline to attain it. You read what others had done, and you took the next step. You didn't earn the knowledge for yourselves, so you don't take any responsibility for it. You stood on the shoulders of geniuses to accomplish something as fast as you could, and before you even knew what you had, you, you've patented it, and packaged it, you've slapped it on a plastic lunchbox, and now you're selling it."

I haven't done any of the calculations for myself regarding magma pump stacks, all I know is that others have and that they use 3x1, that's enough for me. I wouldn't risk trying 2x1 because if it doesn't work then you're in trouble. Either way, if it's 3x1 it's for a reason.

Once the pump is switched off and the magma stops moving then there shouldn't be any more temperature recalculations being done.

[San-A]

Great

Regarding this:

Once the pump is switched off and the magma stops moving then there shouldn't be any more temperature recalculations being done.

Once there is enough magma for the forges, would there be any reason to pump more magma? (does it cool down, so we need to repump it up?)

[KodKod]

Magma will only disappear if it is at 1/7, but since you need something like 4/7 at the least to have a functional magma forge I doubt you'll have any values as low as that, meaning that your magma is now a permanent feature, and allowing you to shut the pump off.

However, it’d be a waste to never use an extensive construction project like a big pump stack again, so I’d suggest using a floodgate to seal off your magma-forge magmaways, and then dig an entirely different path to send your magma along. Like straight outside onto any awaiting elves.

[Girlinhat]

There will always be more elves, and there will always be a demand for more magma.

[KodKod]

There will always be more elves, and there will always be a demand for more magma.

Plus once you have those magma forges up and running you don't need any unsightly trees anymore, clogging up the exterior of your fortress, so burn them all down while you're at it.

Preferably right after an elven diplomat has imposed a tree-cutting restriction on you.

[Girlinhat]

Actually, you can't burn down trees with magma.  Strange as it seems, the one problem that magma can't solve is a wooden problem!

[KodKod]

Actually, you can't burn down trees with magma.  Strange as it seems, the one problem that magma can't solve is a wooden problem!

Only the elves, those insidious bastards, could be responsible for magma-proofing all of the trees.

How can they be clever enough to have the foresight needed to pull that one off and yet still waltz into battle wearing cloth and wielding wood?

[krenshala]

In addition to the bit about 3x1 to maintain temperature, don't forget that the build order of the pumps apparently affects exactly how the magma being pumped is treated.  I believe, but have not yet tested to verify, that the !!scientists!! working the problem discovered that building top down for your pumps give you better efficiency on liquid pumping.

[San-A]

It is funny how every discussion ends with how to use magma to burn elves 

In addition to the bit about 3x1 to maintain temperature, don't forget that the build order of the pumps apparently affects exactly how the magma being pumped is treated.  I believe, but have not yet tested to verify, that the !!scientists!! working the problem discovered that building top down for your pumps give you better efficiency on liquid pumping.

Do you have any references regarding this? What do you mean by efficiency ?

[chris_strain]

I believe that was a reference to this post.

Recently, I've been doing a lot of research on build order.  Because this stuff is tl;dr for a lot of folks, I'm going to start with the practical stuff:

Screw pumps pump in the reverse order in which they were built.  This is probably the most useful finding for most people.  By building top to bottom, you can maximize fluid throughput of a pump stack-- fluid climbing the stack will take z ticks to climb a stack built bottom-to-top, but only a single tick to climb a stack of any height built top-to-bottom.  You can also use this to make improved mist generators.  By building a climbing loop in the direction of water travel, you can guarantee that water spends a single tick in every tile of a mist generator-- to return to its reservoir tile and fall once again into the intake tile of the initial screw pump.

The gist of the theory is that buildings are evaluated from most recently built to first built.  Each building has its own routine it calls during its part of the tick.  The cool part is that all buildings do this.  By paying attention to build order, you can, for instance, pump water into a tile with a pressure plate, trigger that pressure plate with water, and then pump water back out of that tile, all in a single tick.

When you build a pressure plate before a bridge, the pressure plate evaluates its trigger conditions earlier in the tick than the bridge looks for an open signal, and so you get an open in 100 ticks.  When you build a pressure plate after a bridge, the bridge looks for the open signal, doesn't see one, and only later in the same tick does the plate send an open signal, leading to a 1 tick delay in the open signal.

There are some interesting oddities involved in this that I want to detail:

Hatches and doors don't evaluate their own open signals.  Unlike with other furniture, the opening of doors and hatches is not something affected by build order.  Instead, the triggering device opens the door/hatch itself.

The timing of a lever is determined by the 'build order' of the dwarf pulling it, not by the build order of the lever.  Mostly, this doesn't matter, because all dwarves are evaluated before any furniture is evaluated.  However, there's one very interesting experiment that I've done, that you can recreate.  Take two dwarves, and have them take turns pulling a lever to drop the other via the hatch.  One of the dwarves will consistently take 6 ticks to fall, while the other will take 7 ticks.  Why?  Because the hatch is opening before the first dwarf checks to see if he should fall, but after the second dwarf thinks about falling!  I think this is just so cool.  Dwarves, like furniture, appear to be evaluated in reverse order.

Gear assemblies appear to be unaffected by build order, but the actual delivery of power is affected by build order.  This is one of the weird ones.  If you build two gear assemblies, one built before and one after a toggling pressure plate, both gears will change from 'engaged' to 'disengaged' and vice versa on the same tick.  However, the engaged gear assembly built after the pressure plate will not actually deliver power on that tick, whereas the engaged gear assembly built before the pressure plate will!

I realize this kind of stuff isn't very interesting to very many people on the forums, but it's so interesting to me that I felt like I had to share.  If you want to about the various experiments I did to figure this out, I've been keeping an experiment journal at my wiki page.

[Gigaz]

How would one build a pump stack from top to bottom? Wouldn't that make the power supply much more difficult?