Assertion: downward ventilation | /r/HasProperty | necessary
Facets:
value: with upward ventilation
type: OTHER
Source sentences:
text: With downward ventilation by propulsion from three to four times the volume of air is required that is necessary with upward ventilation, the cost being proportionately increased.
text: With downward ventilation by propulsion from three to four times the volume of air is required that is necessary with upward ventilation.