Maximum density estimates based on the measurements of the Fe xiv 264/274 Å ratio during the three C-class flares, as indicated by different coloured points and associated error bars (as described in the legend on each image) for the footpoints K1 (left panel) and K2 (right panel). The solid black curve indicates the theoretical ratio calculated using CHIANTI v8 atomic database. The gray dotted curves represent a ±10% error in the theoretical ratio.