Which of the following factors associated with heliox tend to decrease the Reynold's number? I. density of helium II. viscosity of helium III. specific gravity of helium IV. molecular weight of helium
A. I, II only
B. I, II, IV only
C. I, II, IV only
D. II, III, IV only
?ANS: A
A. Correct response: Whether flow is laminar or turbulent is indicated by the Reynold's number, that is:
Reynold's number = (velocity) (density) (diameter)
viscosity
Because helium has a lower density and a higher viscosity than air, heliox tends to produce a lower Reynold's number, and favors the development of laminar flow. A Reynold's number of less than 2,000 supports laminar flow, and a Reynold's number greater than 2,000 promotes turbulent flow.
B. Incorrect response: See explanation A.
C. Incorrect response: See explanation A.
D. Incorrect response: See explanation A.
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