A vertical flammability tester evaluates the fire resistance of materials by subjecting them to a controlled flame. The test specimen is placed vertically, and a flame is applied to the bottom for a specified duration. The tester measures parameters such as flame spread, burn time, and char length to determine the material's reaction to fire. This testing method helps assess the safety and compliance of materials used in various applications, such as textiles, plastics, and building materials. Horizontal flammability testers operate similarly but with the specimen placed horizontally. Both types of testers are crucial for ensuring product safety and regulatory compliance in industries prone to fire hazards.