Mica Sealed Nozzle Heaters are available in either brass or stainless steel depending on the application. It is recommended to use stainless steel nozzles where the moulding or extrusion of PVC is involved as stainless steel will withstand the corrosive fumes far better. Correct fitment and tightening up of these heaters is critical to ensure not only excellent heat transfer but also longevity. Plastic spillage onto nozzle heaters should be avoided as this tends to suffocate the heater which may result in element failure. Good housekeeping practices are advised at all times .