  The laminar-turbulent transition in the circular pipe flow has been tested
experimentally. The critical Reynolds numbers for the flows of different gases
(He, Ne, Ar, Kr, Xe, N2, CO2, SF6) and liquids (H2O, D2O, C2H5OH) have been
compared. The difference up to 40% was observed. The possible reasons of
non-universality of critical Reynolds number are discussed. The conclusion is
the statistical approach is needed to penetrate into the nature of observed
phenomenon.
