B737 Negative pressure relief valve
Technical questions I could not find in the FCOM nor in "google" with precision, for the 737-800 NG.
As par FCOM 2: Negative pressure relief valve prevents external atmospheric pressure from exceeding internal pressure.
My guess is this valve (which looks more like a hatch) is springloaded. And i'm wondering what is its PSI rating , (what would be the max negative deltaP).
Scenario : Both packs fail, over high MSA, cabin altitude goes above FL140, Cabin alt warning memory item and emergency descent done (outlfow valve MAN closed)
Emergency descent continued as soon as MSA falls back to FL100.
Would it be possible that the cabin alt would still be >FL140 while A/C is at FL100, for 8 min ?
I found this quite disturbing as there is this Negative pressure relief valve and negative pressure would most likely make all seals leak quite a lot...
A >4000ft negative differential pressure is roughly -100hPa = -1.45 PSI