A Rotameter through which air at room temperature and atmospheric pressure is flowing gives a certain reading for a flow rate of 100 cc/sec. If helium (molecular weight 4) is used and Rotameter shows the same reading, the flow rate (cc/sec) is__________________?

Question

Accepted Answer

26. Rotameters are calibrated for a specific gas. When changing gases, the flow rate changes based on molecular weight ratio (M_air/M_He). The new flow rate is proportional to the square root of the ratio.