Alright, this project is the first time I'm actually going to be using pumps, so I'd really appreciate it if I could get feedback on this design. This is from the Mechanical Erupting Volcano thread with what I interpret Girlinhat's design to be.
~ - Magma
0 - Wall
X - Pump facing inwards
0000000
0~~~~~0
0~~X~~0
0~X~X~0
0~~X~~0
0~~~~~0
0000000
Supposedly several layers of this, probably with more storage for magma, will produce a 1x1 tunnel of insanely high pressure, which will result in an explosion of magma out the top of the tower. Can someone with experience with pressure and pumps tell me if this will work?
It actually doesn't matter where the pumps are and what way they face. You could just build a bunch of pumps pointing in random directions in your magma reservoir, and they'll pressurize the magma just fine. This is because the way pressure works, the game sucks magma out the source tile, and then tries to find a place to put it - favoring the lowest open point (which is lower or equal to the pump), and it finds the lowest point by pathfinding - and then it teleports the magma there, not via some logical simulation of fluid movement. This means, that if you have a pump stack going up inside your tower, then the entire pump stack will act to pressurize the magma. If your pump stack goes up 15 tiles above ground, then a ground-level vent will erupt with the output of all 15 pumps. Thus the pump stacks can actually do double duty, both filling magma reservoirs and pressurizing it.
So other things... You only need one pump stack to fill all 4 towers. As long as the towers are connected by underground magma lines, pump-pressure will ensure all the towers fill up (pumps will always fill up to their level, regardless of how convoluted the path the fluid has to take). Of course having a pump stack in each tower would dramatically increase the magma-pressurizing effect, but its not needed if you plan to release the magma by opening the reservoirs.
An even cooler idea would be to build the towers entirely collapsible. Make the bottom walls of the tower out of raised bridges, and include an internal support linked to a lever (bridges, even when raised, wont provide support - but they'll hold the magma in!). When the lever is pulled, the tower will self-destruct, leaving columns of magma momentary hanging in the air before splattering everywhere and drowning everything. Of course the raising bridges could also be used for controlled releases.