Quartz Infrared Heating Elements Medium wavelength radiation.   he most preferred source of heat when rapid heater response is needed.   he heaters are comprises of a series of quartz tubes running parallel to each other within a highly reflective steel housing.   att densities up to 30 w / in.² ( 46.5 kw / m )² Quartz Emitter - Type HFQ Quartz Emitter - Type FFQ Quartz Emitter - Type QFQ Quartz Emitter - Type HSQ Quartz Emitter - Type LFQ