For over 30 years, HSI Fire & Safety has provided fire alarm test and maintenance professionals with a full line of equipment and accessories for functional testing of smoke, carbon monoxide and heat detectors. In 1979, the original smoke detector test aerosol, SmokeCheck, was created. Developed to answer a need for full functionality testing of a smoke detector, SmokeCheck received its first patent and UL listing. Since then, HSI has led the development of additional functional testing mediums and tools for smoke, carbon monoxide and heat detectors. Our patented formulas give you confidence in your testing to know all your detectors are ready to respond. Used by thousands of fire and safety professionals worldwide, our American made detector testing products meet compliance with US and global fire alarm codes and standards.