[F/Fe] versus [Na/Fe] ratios for RGB stars found in metal-rich or intermediate-metallicity globular clusters: 47 Tuc (this work, filled black circles), M 4 (this work, red filled square and Smith et al. 2005, red empty squares), NGC 6712 (Yong et al. 2008, blue empty triangles) and ω Cen (Cunha et al. 2003, green cross). The RGB star of 47 Tuc, for which we have derived an upper limit for the fluorine abundance, is indicated with an arrow oriented towards low [F/Fe] ratios. The [F/Fe] upper limits derived for the stars belonging to the very metal-poor clusters NGC 6397 and M 30 are located well above the upper limit of this plot. Typical errors are around ±0.25 dex in both axes.