Quote: (Originally Posted by
Padowan)
On the WOB issue - does the ANSTI test rig, actually test units under water, or just in a pressurised pot? If it's the former, then the orientation will have an effect as the differential pressure under water between mouthpiece and C/L will be considerably greater than the pressure differential not underwater.
Both.
The pot is filled with water, and ice to get 4C (our version has a refrigerator as well!), then equipment is put in, and the whole lot is pressurised.
Orientation does not make a difference so long as the counterlungs are above the centroid being measured, because the loop is pressured to counteract that offset: in the parlance of the standard, the "loop pressure is optimised". However, if the CL centroid is below the measurement centroid, then it is impossible to do this and the effect is the hydrostatic imbalance is added to the result.
Alex