A comparative study of the effects of chemical additives on the suppression efficiency of water mist

摘要

This paper reports the results of a comparative study of the effects of various salt additives on the flame extinguishing efficiency of fine water sprays. The relative suppression efficiencies are gauged by comparing the extinguishment time of a heptane flame. Preliminary tests are performed in a reduced scale cup-burner; major results are obtained using the closed reduced compartment set-up. The addition of NaCl, KCl or KHCO_3 resulted in large improvements of the suppression efficiency of the water mist. Potassium compounds show the greatest effect as 10% solution of KHCO_3 reduces the average extinction time by up to 96% compared to pure water. The other additives tested have a less noticeable effects, with aqueous solutions of MnCl_2, ZnCl_2 and CuCl_2 showing minimal improvement over water, whereas (NH_4)_2HPO_4, (NH_2)_2CO and FeSO_4·7H_2O actually increasing the time taken to extinguish the flame.