In order to estimate the NVP in a mine, measurements are made at the main fan as shown below.

Fan speed (RPM)	Fan drift pressure (Pa)	Fan quantity (m3/s)
800	655	82.2
950	730	85.5

The NVP in Pa is

The liquid employed in aneroid barometer.

The mechanical mixture of gases existing in a mine given off after explosion called

A Drager Gas Mask does not filter

The resistances of two splits A and Bare 0.35 Ns²m^-8 and 0.05 Ns²m^-8 respectively. The combined resistance of the shafts and trunk airways is 0.4 Ns²m^-8. A booster fan is planned to be installed in split A to increase the quantity flowing through it. Assuming that the surface fan continues to operate at a constant pressure of 1000 Pa, the critical pressure of the booster fan in Pa is