Vents, active vs passive

[NiceGuy]

Hi engeneers,

I know the technical difference between these two. But I wonder if there is any need/benefit in the use of active over passive for gas filtration and ac. Right now I use passive vent for the intake and output.

[Graf Schokola]

You need many pipes at the intake with the passive vent to get the same amount of gas like the active vent.

[Lim Dul]

Passive Vents are often slower then active vents.

The speed of the transfer between the pipe and a passive depends - more or less - on the pressure difference between the pipe pressure and the atmosphere pressure. So for example on mars with a pressure around 2kpa that is incredible slow - and the pipe pressure can't go over the atmosphere pressure.

The active vent on the other hand is not limited by the pressure difference. It just transfers a fixed amount - provided there is enough gas to transfer, which can become a problem on worlds like mars if you place an active vent on every grid.

So it depends on the use case. For gas collecting I would prefer an active vent because that is usualy faster. On high pressure Worlds (Venus for example) a passive vent could work also or might even be faster.

[pryt]

I use passive vents and pressure regulators for my base cooling on Venus.

For example, I made a room, filled with CO2 (started at 200kp/a, now it's at 150kpa, slowly cooling it down to -200°C with 2 Air Conditioners (one running only at night, the other one running when batteries are above 90% charged and switching off again when at 40%). Then setup some pipes from my main base and my greenhouse into there, put some radiatiors on and using 2 digital pipe valves on both lines to control heat flow during the day (base cooling system is only active at night). Power for the cooling system consists of 10 Wind Turbines (the big ones), they generate enough power during the day to keep one air conditioner running at night, and enough during a storm to bring the 10 large batteries to 100% to have both air conditioners run simultaneously for a while.

So, the base is kept in a temperature range of 18°C to 24°C, yes, it's slow, but it's steady, cooling down the main base by about 1°C - 2°C once the 24°C are reached per day and the greenhouse, since it's smaller, by 3°C - 4°C per day (currently the cooling room is only at -50°C).

The pressure regulators are used to fill the base with CO2 and Nitrogen once the pressure drops below 110kpa in two different pipes attached to 2 passive vents, which results in an average of around 95kpa - 105kpa in the base depending on temperature. Once oxygen levels reach 30% a filtration system kicks in, dropping it back to 20%, while CO2 and Nitrogen are slowly filling in to level out the pressure difference caused by the oxygen removal.

The CO2 is from the furnace and at around 100°C (night cooled with radiators) and the Nitrogen at 0°C (from ice smelting for water). No huge impact on overall base temp.


I tried it with active vents aswell, but pipes burst so fast and it over and underpressures due to how ticks are working, and fiddling around with the active vent settings for max airflow ... nah!, so I went back to a somewhat passive and slow system. If you got a rather large area as base it's more easy with a slow system, and less power usage overall.

My cooling system uses about 7kWh during the night and ~500W during the day (including logic). It will use less energy once the cooling room is down to -200°C, although I could keep it at -50°C, but nah!

[hektor]

Also, you can control them with logic.