Forcecage Question

[Lazybones]

Just curious: how much oxygen is in a 10' cube? The spell's windowless cell mode lasts for a minimum of 26 hours, and I was wondering if this meant eventual death for most air-breathing creatures.

 

[Camarath]

IMO this would be upto the individual DM. It would make the spell a no save, no SR death spell for any creature susceptible to suffocation and no larger that Large.

 

[Wippit Guud]

Ok, I'm no science major, but here's what I've come up with....

Human body needs 500 liters of oxygen/day to live.
A 10x10x10 cell (1000 cu ft) is can hold 28316 liters of air
Oxygen is 20% of air, so 20% of that is 5663 liters... so, there's enough oxygen to sustain through the duration. But lack of oxygen isn't want's gonna kill you, CO2 is.

So.

An average set of human lungs hold 6 liters of air. And on each exhale 4% of that volume is CO2. Normal CO2 levels in the air is next to nothing, .0314% We'll say 0% for this.

Humans breath 8-12 times a minute. Since this is a stressful situation, being stuck in a forcecage, we'll go with the high end of 12. 72 litres of gas echanged per second, of which 2.88 liters is CO2

5% CO2 level kills. 5% of a 10x10x10 cell is about 1133 liters. With 2.88 liters/minute of CO2 filling the room, soooooo...

You die in just over 6 and a half hours.

Note: that's based on humans breathing at normal rates. As a DM, I'd say 4 hours.

 

[Camarath]

I as a DM would not allow Forcecage to be used this way. I might if I gave the victim a save (probably Will) and applied SR.

 

[Malachi of Kossuth]

I believe the portable hole also takes up 10 cubic feet and states it has enough oxygen for one medium sized creature for 10 minutes.

 

[Wippit Guud]

Well, if we go 10 minutes for 10 cubic feet, 1000 cu ft would have 1000 minutes, that's 16 hours and change.

 

[CyberSpyder]

I believe the portable hole also takes up 10 cubic feet and states it has enough oxygen for one medium sized creature for 10 minutes.

10' cube = 1000 cubic feet.

If we took the 1 cubic foot holds 1 minute of air route, there would be enough for 16 and 2/3 hours...not quite enough.

 

[shilsen]

As Camarath pointed out, this would make it a no save, no SR insta-kill spell. Since there's no mention of eventual suffocation as a possibility in the spell description, I wouldn't bother with it. After all, it's a kind of magic.

 

[Hypersmurf]

As Camarath pointed out, this would make it a no save, no SR insta-kill spell.

Can you call it "insta" if it takes sixteen hours?

Since there's no mention of eventual suffocation as a possibility in the spell description, I wouldn't bother with it. After all, it's a kind of magic.

Yeah. Wasn't there a Sage ruling that the 3.0 Wall of Force generates oxygen?

-Hyp.

 

[allenw]

A portable hole's interior is a 10'-high cylinder with a diameter of 6' (= 3' radius). The volume is therefore 10' times pi-r-squared = roughly 282.75 cubic feet. If that much air lasts 10 minutes, then 1 cubic foot should last approximate 2.1 seconds, which seems rather low. Then again, *all* sizes of the Bag of Holding also have exactly 10 minutes of air in them, so it must be a side-effect of the magic.

However, the DMG (3.0, don't have 3.5 with me) *does* have official rules for Suffocation on p. 88, including Slow Suffocation. Essentially the same rules appear in the "Wilderness and Environment" section of the 3.5 SRD, where it says:

SUFFOCATION
A character who has no air to breathe can hold her breath for 2 rounds per point of Constitution. After this period of time, the character must make a DC 10 Constitution check in order to continue holding her breath. The save must be repeated each round, with the DC increasing by +1 for each previous success.
When the character fails one of these Constitution checks, she begins to suffocate. In the first round, she falls unconscious (0 hit points). In the following round, she drops to –1 hit points and is dying. In the third round, she suffocates.
Slow Suffocation: A Medium character can breathe easily for 6 hours in a sealed chamber measuring 10 feet on a side. After that time, the character takes 1d6 points of nonlethal damage every 15 minutes. Each additional Medium character or significant fire source (a torch, for example) proportionally reduces the time the air will last.
Small characters consume half as much air as Medium characters. A larger volume of air, of course, lasts for a longer time.

So, it appears that Wippit Guud's science-based numbers are close to the "offical" figure of 6 hours. *However*, I note that, by the rules as written, someone in a sealed chamber never actually dies, they just keep taking nonlethal damage. I'd rule that once they fall unconscious, they "suffocate" in three rounds as per failing the out-of-air CON check (or perhaps they just keep taking 1d6 damage oer 15 minutes, but now it's lethal).