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Author Topic: Quick water pressure question  (Read 796 times)

Shurhaian

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Quick water pressure question
« on: September 12, 2009, 08:15:20 am »

Right, so... I need to provide a well for my dwarves. (Except for the mechanism, it is, for now, going to be entirely out of billon, but that's beside the point.) My fort is entirely below the brook, however; and if I remember the embark map, the underground river is all the way on the opposite side of the map. The "underground pool" is at surface level, so no help there even if it were an infinite water source.

So I plan to make a reservoir. Pump fed to encourage it to fill quickly. The pump is going to be at z=1, the brook is of course at z=0. The reservoir will be at z=-3, under my dining room/meeting hall.

I plan to seal the reservoir with floodgates, both at z=-3; one leading to the pump shaft, the other to a small channel that goes under the well proper.

My question is this: With the inlet floodgate, the one leading to the surface, sealed, does the water lose pressure? Or will it store any pressure thus built up? (It shouldn't, strictly speaking, unless the vessel has a substantial elasticity and thus "stores" the pressure, but I'm not sure how the game renders pressure...)
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kurisukun

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Re: Quick water pressure question
« Reply #1 on: September 12, 2009, 08:24:12 am »

An easier way would be to stick your pump at Z = -4 or Z= -3, thus, de-pressurizing your water.

As for storing pressure, It shouldn't matter that much, as if it does, you're only going to get a little puddle out your well which will quickly evaporate.

Eidalac

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Re: Quick water pressure question
« Reply #2 on: September 12, 2009, 09:06:15 am »

In the case of pumps, the water on the output end is, in reality, created by the pump, so has no relation to the water on the other side, thus it will behave as if it had always been on that level.

In my case, I built my wells by having a long shaft down to let the water in, ending at the pump.  The pump then filled the reservoir, which has no pressure due to the pump.

You can scope out an old map of it at the map archives http://mkv25.net/dfma/poi-11539-deepwell-bottom
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Shurhaian

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Re: Quick water pressure question
« Reply #3 on: September 12, 2009, 09:20:07 am »

The problem is getting the reservoir to that pump in the first place.

I suppose I'd be best off using a dual-pump system? One to get the water out of the brook and to the shaft, perhaps into another reservoir, and the other for filling the reservoir which feeds the well? (Which, at that point, might not need floodgates...)

The catch with this is making a self-contained system. If I'm going to have manually-operated pumps, I'd rather they be close to my fortress proper, not down a moderately long accessway. I was hoping the floodgates would be enough, that the water wouldn't all come boiling out the other end so long as I handled the floodgates properly.
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Eidalac

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Re: Quick water pressure question
« Reply #4 on: September 12, 2009, 01:27:20 pm »

Yeah, using a 2-pump system would be the safest bet.  You could use floodgates, but pumps are more secure with the whole pressure-rest thing.

As far as powering them goes, the source pump (brook) should be easy to work with dwarf power - so long as you seal the output end, water can't flow back onto the input end, which is where a dwarf would stand to power it.

However, the pump into the well reservoir will have it's input end flooded, since the water coming down the shaft will pile up to reach the level of the source pump.  Only way I could see around that would be to use a pressure switch linked either to the source pump or a flood-gate, in order to stop water flow before it can get that high.

I've always used water-wheels myself, though running the shafts for power transfer is something of a bother, once it's sealed properly I never have to think about it again.  Not sure if you can build them on brooks, though, but if not you can build them over the water you pump, since thermo-dynamics are just elven lies.

Also, if you go down far enough for the well reservoir, it's easy to expand it to feed other wells, if for some reason you feel like it.
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Shurhaian

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Re: Quick water pressure question
« Reply #5 on: September 12, 2009, 04:26:03 pm »

The design I'd initially thought of turns out to work fine; pressure doesn't get "stored" in water(if I'm now reading the Wiki right, "pressure" only follows adjacent water orthogonally, though water can flow unpressurized through the diagonal of course). So I have one pump at the brook(which is channeled away appropriately) to supply water, which goes into the channel, down the stairwell, along the other channel, past a floodgate, and into the reservoir. When that floodgate is closed, all's well; I just open the other floodgate, and it spills through that floodgate and into the single tile beyond, which is where the well is over.

Probably supply my fortress for years even if I got sieged and had no other drinks.

Next step: Also rig the reservoir to an underground farm system! Small rooms with floor hatches over the farm plots to be will likely work...
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Eidalac

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Re: Quick water pressure question
« Reply #6 on: September 13, 2009, 02:53:18 am »

Next step: Also rig the reservoir to an underground farm system! Small rooms with floor hatches over the farm plots to be will likely work...

Another method:  Build a holding tank that you can pump water into from the reservoir, linked to the farm area via a floodgate.  The holding tank should be just a bit more than 1/7th the size of the farm area, so that when it is opened it puts out enough water to cover the farms with 1 deep water.

Ideally, link the lever for the floodgate to the power source of the pump, so that the pump is always off when the floodgate is open.  Or just set a pressure switch to shut the gate if water flows out of the farm area.
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Shurhaian

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Re: Quick water pressure question
« Reply #7 on: September 13, 2009, 09:12:42 am »

The reason I'm going with the overhead cisterns (relative to the farm plots) is one of wasted water. If they're on the same level as the reservoir, I need to take the size of the reservoir into consideration when calculating how much water I need. A 2x2 room with an extra tile dug out, however, stores 35 units of water; even counting the bits that won't leave the reservoir's tiles, this should spread neatly around the farm with only a bit left over.

The farms themselves I plan to have sealed with lever-activated doors. Not quite as neat as linking it all to some other aspect of the system, but... it'll work. And I intend to use the Notes system liberally.
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Dorf3000

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Re: Quick water pressure question
« Reply #8 on: September 13, 2009, 09:36:19 am »

If you really didn't want to worry about pressure or flooding, you could just put a floodgate and a bridge in the channel to the river, and attach them to the same lever.  Then each time you toggle the lever, you get X units of water added to the system (where X is the size of the tunnel between the two items)

There's even a chance for some Fun if you forget what it does and set it on repeat..
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Lemunde

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Re: Quick water pressure question
« Reply #9 on: September 13, 2009, 11:07:50 am »

Why do you even need to use pumps in the first place?  Can't you just channel the brook into a tunnel that leads to your cistern and block it off with a single floodgate?  You could close the flood gate with a pressure plate or if you watch carefully you could just use a lever.  I've created underground pools several times using this method.  I've never had to use a pump.

Quote
Closing a floodgate when submerged

For this example, say we want to close a floodgate when a reservoir reaches a depth of 5.

    * Build the pressure plate, set to activate under water (w) from 0 (a, s) to 4 (z, x). Make sure it is set to reset (o) (The default is to resetv0.28.181.40d; it's in the correct state when the screen reads 'Resets').
    * Place the floodgate
    * Connect a lever to the floodgate, and open it.
    * Optionally remove the lever.
    * Connect the pressure plate to the floodgate.
    * Allow the pressure plate to be submerged.

The floodgate should close a few seconds after the water reaches a depth of 5 or more, and open again when the depth falls to 4 or less.

It's worth noting that the reaction time of the pressure plate-floodgate system is quite large - the reservoir may overflow before the floodgate shuts. In order to prevent this (for example, when building a well filled from a river or brook), build a run-off pool. This allows the gate enough time to close, and the water will spread out instead of overflowing as it would have in a smaller pool.
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Shurhaian

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Re: Quick water pressure question
« Reply #10 on: September 13, 2009, 11:32:41 am »

The last time I tried to rely on natural water flow to get the job done(it was from an underground river, but still), my dwarves were dying of thirst before the water got there. And it wasn't THAT long a tunnel.

Natural fluid flow is iffy in tight spaces, it seems.
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Bedsheet

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Re: Quick water pressure question
« Reply #11 on: September 13, 2009, 11:42:35 am »

Why do you even need to use pumps in the first place?  Can't you just channel the brook into a tunnel that leads to your cistern and block it off with a single floodgate?  You could close the flood gate with a pressure plate or if you watch carefully you could just use a lever.  I've created underground pools several times using this method.  I've never had to use a pump.

   Why because Sir your system is entirely too simple to be built by Dwarves!  Have a little self respect!!
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