Editing v0.31:Screw pump

{{quality|Masterwork|21:05, 26 April 2011 (UTC)}}
{{Machine_component|name=Screw pump|key=s|job=[[Pump operator]]
|construction=
* [[Block]]
* [[Trap component#Enormous corkscrew|Enormous corkscrew]]
* [[Pipe section]]
|construction_job=
* [[Architecture]]
* 1 of
** [[Carpentry]]
** [[Masonry]]
** [[Metalsmithing]]
|power=Needs 10 power.
}}
{{av}}

A '''screw pump''' is a small [[building]] that can lift liquids ([[water]] or [[magma]]) from one level below onto the same [[Z-level]] as the pump. It is two tiles by one tile in size, and it can be either manually operated by a [[dwarf]] with the [[pump operator]] job or by being [[power]]ed by [[water wheel]]s and/or [[windmill]]s. 

The direction you want the fluid to travel must be chosen at the time of construction.  Pumping only occurs in a straight line, and involves a total of 4 tiles in a row - the liquid source, two for the pump, and the output. The "rise" in levels occurs on the first tile, the intake side, from one level below up to the level of the pump*.  Pumped fluids can and will flow immediately after being pumped, as normal for that fluid.  Pumped fluids will have a [[pressure]] equal to the exit [[z-level]] - a pump never "forces" water to a higher [[z-level]] than the output tile.

:''(* A DF pump can best be imagined as a simple [http://en.wikipedia.org/wiki/Archimedes%27_screw archimedes screw].)''

[[Water#Salt Water|Salt water]] pumped through a pump will desalinate and become drinkable, but only if the cistern has never contained salty water. [[Water#Stagnant Water|Stagnant water]] pumped through a pump will become clean, letting dwarves drink it without getting an unhappy [[thought]] and letting [[doctor]]s clean [[wound]]s without causing an [[Health care#Infection|infection]].  As with desalination, this only works if the cistern has never contained stagnant water.

''For a basic overview of how the different machine parts work and work together, see [[machinery]].''

== Construction ==

Building a screw pump requires an [[Trap component#Enormous corkscrew|enormous corkscrew]], a [[block]], and a [[pipe section]]. The construction itself is completed in two stages. First a dwarf with the [[architect]] labor must design it. Then a dwarf (the same or a different one) with the appropriate labor must complete the building. This could be [[carpentry]], [[metalsmithing]], or [[masonry]], depending on the material of the block.

To select pump, use keys {{k|b}}-{{k|M}}-{{k|s}}. It's important to choose the proper orientation for your pump, where it will draw water from and where it will deliver the water.  This is determined before placement with the {{k|u}}, {{k|m}}, {{k|k}}, or {{k|h}} keys, and the text at the top of the sub-menu will change to confirm your choice.  The default (as shown above in the sidebar), "pumps from the north" (top).  The ''light'' green X must be next to the liquid source and the ''dark'' green X is where the liquid exits the pump.

[[Image:Small pump.jpg|thumb|right|300px|'''Basic Side View of a Pump'''. <br /> This pump "pumps from the west", from left to right.  The area to the right may fill to the top of that level, but no more  (See [[pressure]]; see [[Screw pump#Pump Stack|Pump stack]]). Note that the entire space required is 4 tiles long by 1 tile wide, not including any retaining walls for the outflow.   If pumped manually, the [[pump operator]] stands in the light-colored area, as the dark-colored is impassable to both fluid and movement.<br /><br />''(Although the "liquid" is shown as blue, this can work for [[magma]] as well, with the [[magma-safe|appropriate precautions]].)'']]

The example shown in the infobox above "pumps from the north" (top) to the south (bottom).  If pumped manually, the dwarf stands on the light-colored tile, as the dark-colored is impassable.

The orientation is visible after placement by using {{k|q}}uery over or near that pump or during placement, using UMKH to select the direction of input.  Orientation of a pump cannot be changed after being constructed, but, as with any building, it can be deconstructed into its component parts and rebuilt as and where desired.

Having specified the direction of travel, you must ensure that the source side of the pump is placed adjacent to and above (in the [[z-axis]]) a liquid. The screw pump will draw the liquid up from below its level, and distribute it out of the other side of the pump.

== Notes ==

* The source of the pump must be directionally adjacent to "Open Space" that is directly above a source of liquid. The adjacent space cannot be a floor, stairway or wall suspended over water. Screw pumps can pull water through a [[grate]], floor [[bars]], or a [[construction|constructed]] [[fortification]] on the Z-level below.
* The light pump tile is where a pump operator will stand (if the pump is not powered mechanically).  Liquids to be pumped must be 1 level below the (empty) area adjacent to this tile.  
* Dwarves must be able to access and stand on the light tile of the pump in order to build the pump and then to be able to operate the pump manually.
* The dark pump tile is on the output side.  Liquids will appear in the tile adjacent to this.
* The dark pump tile blocks liquids flow and creature movement, and can be built between wall segments to create a solid barrier.  The light tile of the pump does not block flow or movement.
* Pumps can also be used in conjunction with a [[water wheel]] or a [[windmill]] to become self-powered.
* Active mechanisms connected to the pump will automatically start the pump; to prevent this either restrict liquid flow using floodgates or hatches, or put in a [[gear assembly]] linked to a [[lever]] to disconnect the [[power]].
* Adjacent pumps ''automatically'' transfer mechanical power to any other adjacent pump(s); no [[axle]] or [[mechanism]] is required.  If too many pumps are adjacent, there may be insufficient power to power them.
* Dwarves operating pumps do '''NOT''' generate power. Thus, one cannot use a single [[pump operator]] to power an entire pump stack.
* A hatch above the input tile (on the same level as the pump) that is linked to a trigger (a [[lever]] or [[pressure plate]]) makes an effective on/off switch for that pump.
* In order to build pumps in a "hanging" state, as in the stacked screw pump example (below), one of its tiles must be able to connect to a nearby machine, either already existing or designated to be built. If, when the screw pump's construction is completed, the supporting mechanism has not yet been completed, it will promptly collapse into its component parts.
* Pumps do '''not''' push liquids '''up''' additional Z-levels above them.  They only deliver water to their own level.  That is, if you direct the output of a screw pump into a 1-square space surrounded by walls, the water will not "overflow" the walls. Consequently, a pump will refuse to move liquid if the level it is pumping to is completely filled.  Higher levels can be achieved using a "pump stack" (below). (See [[Pressure]])
* In order to safely pump magma, you must use [[magma-safe]] materials, though magma-unsafe metals have been observed to be safe unless the open tile is going to be submerged in magma. Wooden parts (except for [[nether-cap]]s) will burst into flames the instant the pump is activated, and magma-unsafe stone [[block]]s melt after a short time. Despite the requirement for magma-safe materials, the exterior of the pump does not heat up, and dwarves do not mind operating a magma pump directly.
* Magma, which normally has no pressure, will behave as though pressurized when pumped. For example, when pumped into an U-turn, magma will come out at the other end. Normal (non-pumped) magma would just pool at the lowest level. This may be either very useful (can be used to build pressure towers for magma) or deadly (forge level flooded with magma, because someone tried to pump magma into a volcano).
* Pump's pseudo-pressure doesn't work across diagonals. If there is a diagonal-only passage in your tunnel, liquids will seep slowly through it, instead of bursting through above their normal maximal speed, like they would if there was good passage.
* The liquid in a pump's intake tile must have a depth of at least 2/7 for the pump to be able to remove any amount of liquid from it.
* If a pump's intake tile on the z-level below the pump becomes blocked (as with a cave-in or magma cooling into obsidian) the pump will still run but not pump any fluid.
* If a pump's output tile contains magma and the pump is pumping water or vice versa, the output tile will be turned into [[obsidian]].

====Common mistakes====
* Orienting a pump incorrectly, and/or not having a proper open liquid source.
* Pumping water into an area with a path to other parts of your fortress. (The pump may work perfectly - the fortress quickly [[flood]]s.)
* Expecting water to rise up above the same level of a pump.
* Building a wall attached only to the light tile - this leaves a diagonal leak between the wall and the dark tile unless sealed there.  (If that's not a problem, don't worry about it.)
* Having stairs as input tile. Stairs block input tile, thus rendering the pump useless, even though liquids usually ignore stairs. Output tile can be any liquid-passable tile.
* Not channeling below the impassable tile of an individual pump in a pump stack.  This is how power is transmitted to the pump below.
* Pumping magma into a lower z-level (same as the source) and then being surprised it is forced back up to the pump's z-level further down the line (where you were planning your magma forges, for example.)

== Example layouts ==
=== Single pump ===

[[Image:jt_screwpump.png|frame|left|A screw pump delivers from the level below to the tile in front. This pump pumps from the right to the left.  The "dark tile" would be on the left - that entire tile is impassible to movement and fluids.]]<br style="clear: both"/>
=== Pump stack ===
[[File:PumpStack2010.png|thumb|right|300px|'''Illustrated Side View of a Pump Stack'''.]]
[[File:PumpStackTopView.png|thumb|right|300px|'''Illustrated Top View of a Pump Stack Layer'''.]]
A Pump stack is a method used to draw water or magma vertically across multiple z-levels requiring a minimum of parts. The basic functionality is possible because the Output (dark) side of the pump can be built over open space with a machine component located directly below, in this case another Screw Pump. Note that for power to properly transfer the intake (light) side of the pump must line up with the output (dark) side of the pump on the floor above it through a space in the floor, as in the illustration.

A pump stack minimizes the amount of machinery required to lift water or magma by allowing for power to be supplied directly to only the most accessible pump (typically the topmost) which in turn allows the player to operate a stack limited only by how many windmills/water wheels they can fit into the area.  The price of optimal parts density is fragility: each pump relies on the pump below it for support.  If [[forgotten beast|anything]] breaks a pump in your stack, every pump above it will be disassembled.  This means that a single pump accidentally assembled with non-[[magma-safe]] parts can cause an entire magma pump stack to spontaneously disassemble.

Typical applications for a pump stack include moving magma from a lower level (often the [[magma sea]]) up to a convenient level for forges and furnaces, extracting water from a flooded fort, raising water for a decorative [[waterfall]] (and extracting it afterwards), or any other purpose that requires water/magma on a z-level significantly above its current location.  

The Illustrated Top View of a Pump Stack Layer shows a basic section of a pump stack. Only the door (or a floodgate) on the Containment side is strictly necessary in order to prevent flooding. Two doorways are used here, each lining up with the solid ground within the pump assembly, in order to prevent workers from trapping themselves after digging channels or assembling the pump.

Be warned: pump stacks move water '''fast.''' If you are pumping from a large reservoir into an open area, be prepared for a huge outflow, roughly akin to the kind of water dump you'd get if the whole reservoir was balanced above the pump output and then released. If you are using pumps to empty a large underground reservoir (or, say, a flooded fortress) onto open land, use an aqueduct or some other method to make sure the pump system outlet is a good distance away from anything you wouldn't want to get drenched.

As an alternative to a large reservoir, it is also possible to combine a [[Dwarven Atom Smasher]] with the top layer of the Pump Stack to create a "vacuum cleaner" of sorts.

====Tips====

* Ramps can be used in place of channeling. Liquids will transmit through ramps, unlike stairs, and when pumps are constructed they annihilate the ramp they're built on much as walls do. Power will still be transmitted, so they don't need to be removed by miners prior to pump construction. Ramps make it virtually impossible to strand your miners and allow the stack to be dug out using only access doorways on the intake side of the pump, so no construction or doors are later needed to eliminate leaks. A pump stack can be very rapidly carved out with this method as even if a miner/builder is trapped on the containment side of a pump, they can walk up the ramp to the intake side of the pump above and walk out.
* Power can be transmitted to the stack by channeling out the tile directly above the intake (light) tile of the topmost pump and mounting a gear assembly. If the gear assembly is supported by an adjacent gear assembly or horizontal axle on a stable floor (be careful to not have that adjacent gear assembly disengage via lever), this will allow the stack to hang from the gear assembly. If a lower pump needs to be removed, or should self-destruct, the problem of the entire pump stack disassembling described above is eliminated. Further, if the supported gear assembly is built first, the pump stack can be built both from the top and bottom simultaneously, halving construction time, assuming that sufficient attention is paid to make sure that the pumps will align with the proper orientation when the two partial stacks meet. Properly channeling/ramping out the stack should ensure this.
* When pumping water or magma, make sure any underground soil tiles on the containment side of the stack are covered with a [[construction|constructed]] floor or [[fortification]] to prevent subterranean trees from growing and blocking flow of the stack. The material need not be magma-safe, and fortifications have the added advantage that, when used with water, they will never become muddy.

===Improved Magma Pump Stack===

Because a pump stack pumping magma is known to cause significant [[Maximizing_framerate|lag]], a [http://www.bay12forums.com/smf/index.php?topic=72296.0 new type of pump stack] was developed by [http://www.bay12forums.com/smf/index.php?action=profile;u=19835 NecroRebel] that causes a much smaller drop in [[FPS]].  Changing the single tile magma chamber at the output of every pump from a 1 by 1 to a 3 by 3 area reduces the lag to 1/15th of that caused by the original pump stack. The designer hypothesizes that the larger chamber requires many fewer temperature calculations when magma is pumped in or out; that also implies that there will be no improvement for water pumps.

====Newer Magma Pump Breakthroughs====

Newer breakthroughs in magma pump design has since made the 3x3 reservoir design obsolete.
NecroRebel has tested a [http://www.bay12forums.com/smf/index.php?topic=72296.msg1772802#msg1772802 1x3 head-over-tail variation] (which is very similar to [[Screw_pump#Pump_stack|the typical 1 by 1 pump stack]]) as well as a [http://www.bay12forums.com/smf/index.php?topic=72296.msg1795907#msg1795907 2x3 head-over-head variation]. Both of these new designs require less space and work as effective as his original 3x3 reservoir head-over-head design, with no significant drop in FPS. The 1x3 head-over-tail design has the advantages of requiring the least amount of space and being simple to refit from the standard 1 by 1 water pump stack.

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