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The observed evolution of the gas fraction and its associated depletion timein main sequence (MS) galaxies provides insights on how star formation proceedsover cosmic time. We report ALMA detections of the rest-frame $\sim$300$\mu$mcontinuum observed at 240 GHz for 45 massive ($\rm \langlelog(M_{\star}(M_{\odot}))\rangle=10.7$), normal star forming ($\rm \langlelog(sSFR(yr^{-1}))\rangle=-8.6$), i.e. MS, galaxies at $\rm z\approx3.2$ in theCOSMOS field. From an empirical calibration between cold neutral, i.e.molecular and atomic, gas mass $\rm M_{gas}$ and monochromatic (rest-frame)infrared luminosity, the gas mass for this sample is derived. Combined withstellar mass $\rm M_{\star}$ and star formation rate (SFR) estimates (from {\scMagPhys} fits) we obtain a median gas fraction of $\rm\mu_{gas}=M_{gas}/M_{\star}=1.65_{-0.19}^{+0.18}$ and a median gas depletiontime $\rm t_{depl.}(Gyr)=M_{gas}/SFR=0.68_{-0.08}^{+0.07}$; correction for thelocation on the MS will only slightly change the values. The reporteduncertainties are the $\rm 1\sigma$ error on the median. Our results are fullyconsistent with the expected flattening of the redshift evolution from the2-SFM (2 star formation mode) framework that empirically prescribes theevolution assuming a universal, log-linear relation between SFR and gas masscoupled to the redshift evolution of the specific star formation rate (sSFR) ofmain sequence galaxies. While $\rm t_{dep.}$ shows only a mild dependence onlocation within the MS, a clear trend of increasing $\rm \mu_{gas}$ across theMS is observed (as known from previous studies). Further we comment on trendswithin the MS and (in)consistencies with other studies.

Gas Fraction and Depletion Time of Massive Star Forming Galaxies at z~3.2: No Change in Global Star Formation Process out to z>3