Hydrometers for special applications:
without and with thermometer.
hydrometer H860632 acid sulphuric
should be suitable for Qualicoat requirements (the range 180-220 g/l sulphuric acid corresponds to 15-20% H2SO4).
However, please only note that this article has a ref.temp. of 15°C, i.e. if measurements are done at about 25°C (between 20 and 30°C), a correction has to be considered of about -0,7%.