Got this from a friend which allegedly was in continuous use for 35 years!!, the (Firebird) boiler was/is running on a mixture of 75% "diesel" + 25% kerosene, the nozzle itself seems to be of a different material to the modern ones, it was spotlessely clean when I dissassembled it, I would love to know how much wear has taken place in the orifice during this period.