Choosing a seal material for Hydrochloric Acid, Cold 37%
The table above rates every common O-ring elastomer for service in Hydrochloric Acid, Cold 37% on an A–D scale. A is Excellent, B is Good, C is Fair (test before relying on it), and D is Not Recommended. An X indicates insufficient published data.
For Hydrochloric Acid, Cold 37%, the strongest candidates are Hydrogenated Nitrile, Fluorocarbon (Viton), Perfluoroelastomer, Aflas (TFE/P). These ratings are representative at ambient conditions (~20°C). Compatibility shifts with temperature, concentration, pressure and exposure time, so always validate the material against your real operating envelope before committing to a design.