Every base needs supplies: oxygen for breathing air, nitrogen as filler gas, fuel, coolant. This article shows which stores exist, how much fits in them and how to fill them so that no pipe bursts during the next heat wave.
Since 0.2.6143: tanks are pipes
The most important change first: since version 0.2.6143 tanks are part of the pipe network. A tank you build today behaves like a very thick pipe piece. It has no data port and no logic of its own; its volume simply counts towards the network.
The older tanks with a data port – such as the Small Tank or Large Tank – only exist in old saves. They have their own inner volume that equalises with the pipe every tick. Pumps therefore work more slowly on them, because per tick they only get hold of the pipe volume.
The stores at a glance
| Store | Volume | Kit |
|---|---|---|
| In-Line Tank Small Gas | 100 L | 1 × Kit (Pipe Utility Gas) |
| In-Line Tank Gas | 250 L | 2 × Kit (Pipe Utility Gas) |
| In-Line Tank Gas 1x3 | 360 L | 3 × Kit (Pipe Utility Gas) |
| Small Tank | 6,000 L | 1 × Kit (Tank) |
| Large Tank | 50,000 L | 5 × Kit (Tank) |
| Tank Small (Insulated) | 6,000 L | 1 × Kit (Insulated Tank) |
| Tank Big (Insulated) | 50,000 L | 5 × Kit (Insulated Tank) |
| Liquid Tank Small | 6,000 L of liquid | 1 × Kit (Liquid Tank) |
| Portable Gas Tank | 790 L, portable | Kit (Portable Gas Tank) |
All kits are made by the Hydraulic Pipe Bender. For liquid the same sizes exist, insulated too.
How much fits
The gas law tells you: n = p · V / (R · T). A small tank of 6,000 litres at 20,000 kPa and 20 °C holds:
- n = 20,000 · 6,000 / (8.3144 · 293.15) ≈ 49,200 mol
A room of four cells needs about 1,330 mol at normal pressure. So this tank fills it a good 35 times.
Measuring
Because the tank has no logic of its own, you measure it through the network. Put a Pipe Analyzer on a pipe connected to the tank. It gives Pressure, Temperature, TotalMoles and Volume for the whole network – tank and pipes together.
Safe filling: by moles, not by pressure
The pressure in a store changes with temperature; the amount does not. With the same amount, pressure rises in the same ratio as the temperature in kelvin. So keep a margin:
- Gas networks hold 60,795 kPa and count as stressed from 80 %, about 48,636 kPa.
- If you fill to 75 % (45,596 kPa) at 20 °C and the gas warms to 50 °C, you get 45,596 · 323.15 / 293.15 ≈ 50,260 kPa – already above the stress limit.
- If you only fill to 60 % (about 36,500 kPa at 20 °C), the network stays below it up to 100 °C: 36,477 · 373.15 / 293.15 ≈ 46,430 kPa.
It is safest to fill to a target amount in moles that you calculate for 20 °C. That number stays the same, however warm the gas gets later.
An old tank with its own inner volume takes 5 damage per tick from a 60,795 kPa difference to its surroundings. If it is destroyed, its whole contents end up in a single cell.
IC10: filling by moles
The program works out the target amount from the network volume and a target pressure at 20 °C and switches the pump off once it is reached. rgas is the built-in gas constant 8.3144.
# Fill a store by moles
define PUMP -321403609 # Volume Pump (StructureVolumePump)
define ANALYZER 435685051 # Pipe Analyzer (StructurePipeAnalysizer)
define NPUMP HASH("Store Pump")
define NANALYZER HASH("Store Analyzer")
define TARGETP 36000 # kPa, referred to 20 C
define REFT 293.15 # K, equals 20 C
alias volume r0
alias moles r1
alias target r2
alias run r3
start:
yield
lbn volume ANALYZER NANALYZER Volume 0
bnan volume start # no analyzer with this name
lbn moles ANALYZER NANALYZER TotalMoles 0
mul target TARGETP volume # p * V
div target target rgas
div target target REFT # n = p * V / (R * T)
slt run moles target # too little: pump
sbn PUMP NPUMP On run
j startFor a small tank with some pipe (6,100 litres together) that gives about 90,100 mol. The pump stops as soon as that amount is reached – even if the gas happens to be warm and the pressure therefore looks higher.
When insulation pays off
Insulated tanks exchange no heat with their surroundings: radiation, convection and solar heating are 0 for them. That pays off when
- the contents should stay cold, for example as a cold store for a cooling loop,
- hot gas should act as a heat store,
- the surroundings are extreme. On Venus (737 K) a tank filled at 20 °C to 20,000 kPa would rise to about 50,300 kPa without insulation.
Then insulate the pipes up to the tank as well, otherwise the heat is lost there.
Storing liquid
Like liquid pipes, liquid tanks only hold 6,079.5 kPa. Their pressure only shows something shortly before brim-full and then jumps all at once. So fill them by fill level, i.e. VolumeOfLiquid divided by Volume, and stop at about 90 %. A ready-made program is in Pipes and lines: gas, liquid, insulated. Water takes 0.018 litres per mole: 6,000 litres are about 333,000 mol.
Where next
- Pumps, valves and pressure regulators: which part for what – pumps and regulators at the store
- Evaporating, condensing, freezing: using phases on purpose – storing gases as liquids
- Atmosphere and pressure – the gas law in detail
- Calculator for gas amounts: Gas calculator