Hi
yesterday I received the gt500 afco h/e and did some measurement and calculations compared to cobra afco h/e
Correct me if I am wrong
Gt500 has 23 (23.8"×1.2") tubes
23.8 × 1.2 = 28.56 cu in each tube
28.56 × 23 = 656.88 cubic inches. total service area
Cobra has 11 (28.5"×2.25) tubes...
The gases don't need vacuum to be evacuated from the case it's just build up and escape from the easiest way.
and this the point "(besides allow positive pressure to have some kind of escape)."