Blocked nozzles affect the efficiency of the forehearth since they restrict the amount of combustion that needs to be applied. The nozzles rely on the passage of the air/gas mixture to cool the nozzle tips. As the nozzles block the cooling effect become less and the nozzle overheats. This causes the destruction of the nozzle and can cause the air/gas mix to explode within the burner pipe. Although in most cases the critical combustion components are protected by explosion safety devices, eg, Tess safety heads, the explosion can result in the displacement of burner pipes and couplings. This in turn can cause leakage of gas.