Working principle of fire retardant coating tester and sample preparation

Working Principle and Sample Preparation of a Fire Retardant Coating Tester
The Fire Retardant Coating Tester was developed based on the technical requirements of GB12441-2005 and tailored to my country's specific conditions. It is suitable for testing the flame retardancy of decorative fire retardant coatings applied to combustible substrates. The instrument utilizes a touchscreen control system, fully automating the entire testing process, and achieving temperature errors below national standards. The Fire Retardant Coating Tester boasts a rational design and easy operation and maintenance, making it a valuable tool for researchers conducting fire retardant coating research. A detailed review of the national standard "GB12441-2005: Decorative Fire Retardant Coatings" before testing will assist you in your testing.

Working Principle of the Fire Retardant Coating Tester: Throughout the test, the flame temperature of the DBF-3 Fire Retardant Coating Tester (Large Plate Method) conforms to the T-To = 345log(8t+1) function curve, also known as the time-temperature standard curve. The corresponding representative value serves as the basis for the set temperature rise (hereinafter referred to as the set temperature). The set temperature and the thermocouple signal are simultaneously fed into the amplifier for comparison. When the thermocouple temperature exceeds the set value, the valve motor automatically shuts off the air flow, lowering the flame temperature. When the thermocouple temperature falls below the set value, the valve motor automatically opens the air flow, raising the flame temperature. This ensures that the flame temperature at the thermocouple consistently follows the pre-set standard curve. When the timed standby temperature reaches 220°C, an automatic alarm is issued.

Operation Panel, Back Panel, and Bracket Installation Diagram:
1. Instrument Back Panel
2. Test Bracket Installation Diagram
1. Specimen Preparation
1. Test Base Material Selection and Dimensions
The test base material is Grade 1, five-ply plywood with a thickness of 5mm + 0.2mm. The test panel measures 900mm x 900mm. The surface must be flat and smooth, and there must be no seams or knots within 250mm of the center of one side of the test panel.
2. Coating Ratio
For single-sided coating, the wet coating ratio is 500g/m². The coating tolerance is the specified value + 2%. If multiple coatings are required, the interval between coats must be at least 24 hours.
3. Conditioning
After coating with the decorative fire retardant coating, the specimens should be conditioned under ambient conditions of (23 ± 2)°C and (50 ± 5)% to maintain a constant mass (mass change of no more than 0.5% between two weighings 24 hours apart).