I'm planning on ending my life via a nitrogen exit mask, but I can't figure out what flow rate I should use. Some sources say 15 liters/minute, and others say 20 liters/minute.
Don't PPH and PPEH recommend 25 lpm for masks? This seems more logical than 15 lpm, since 250 ml/s may be significantly less than the peak inspiration flow rate.
According to common data, a typical respiration cycle in rest for an average healthy adult consists of 3 stages: inspiration of 500 - 600 ml air in 1 - 2 seconds, expiration, and automatic pause. During an expiration followed by an automatic pause, any portion of gas coming into the mask from the cylinder just displaces the gas mixture inside the mask into the ambient atmosphere. Inhaling of 500 - 600 ml in 1.5 seconds corresponds to the average inspiration flow rate of 333⅓ - 400 ml/s (that is 20 - 24 l/m). The peak inspiration flow rate exceeds the average one, because the immediate flow changes over time in a manner indicated on the following diagram
The maximum inspiration flow rate may be greater than 30 l/min.
This source mentions the peak inspiration flow rate of 33.64 l/min at the 0.525 s timestamp - see the description for Figure 5.
In
this study, the peak inspiration flow rate for the tested people was determined to be 38.9 ± 2.7 l/min, the mean flow rate - 31.3 ± 2.1 l/min, and the comfort settings of the ventilator - around 34 l/m.
Now let's assume that in your setup only 15 l/min can be delivered to the mask. How would you get the remaining 15+ l/m for the peak consumption of 30+ l/m? In the absence of an inflatable storage, you'd either had to compensate the lack of gas by capturing air from the ambient atmosphere (if the design of the mask allows this) or restrict your inhalation to match the limitation of the gas flow coming from the cylinder.