Chemical heaters are used in the electroplating, metal finishing and chemical industry. It is an over the side (OTS) type and comes in 4 different sheaths, Quartz, Titanium, Stainless steel, Teflon.
Be very selective in your consideration of the Chemical heaters sheath construction. The sheath of the Chemical heater function as a heat transfer surface, and thus is operating at temperatures above the control temperature of the process. Such temperature and fluid movement impose severe corrosion conditions on the metal surface.
Success of your choice of sheath material will depend upon many factors which are within your power to control.