Fire Retardant Paints Burning Test Apparatus (Tunnel Method)

What is the Fire Retardant Paints Burning Test Apparatus (Tunnel Method)?

The Fire Retardant Paints Burning Test Apparatus (Tunnel Method) is a specialized device used to evaluate the fire-resistant performance of fire-retardant paints. In this test, paint-coated samples are placed in a tunnel-like chamber where they are exposed to controlled flame or heat conditions to simulate fire scenarios. The apparatus measures how well the paint slows down ignition, limits flame spread, and reduces heat release on the coated surface. 

Compliance： ASTM D3806/ISO 846/MIL-STD-810G（Method 508.6)/JIS Z 2911

The main technical parameters:

1 Tunnel furnace:

1.1 It is composed of angle steel frame and ceramic fiber board (asbestos cement board).

1.2 The angle steel frame is welded by 35 mm<30 100="" 610="" mmx2="" mm="" angle="" steel.="" the="" top="" of="" steel="" frame="" is="" long="" and="" wide="">

1.3 The flue end of the tunnel furnace is open; there is an air supply hole with a diameter of 25 mm at the center of the bottom of the tunnel furnace 110 mm away from the base.

1.4 The observation window of the heat-resistant glass plate is located under the side of the specimen support, and is made of a piece of quartz glass or heat-resistant laurel glass with a length of 622 m, a width of 50 mm, and a thickness of 3 mm. Mark the glass from 100 mm to 500 mm at one end at intervals of 25 mm. Above the observation window is a metal sunshade that slopes down 60°. Inside the specimen holder is a serrated stainless steel calibration plate with a pitch of 25 mm.

1.5 On the side of the test plate support, above the centerline of the burner, there is a thermocouple insertion hole with a diameter of 3 mm, so that the hot junction of the thermocouple is delivered to the back fire surface of the test piece.

1.6 The tunnel furnace should be placed in a room without forced ventilation.

2 Burner:

2.1 Burner: made of brass, with a top diameter of 20mm and a height of about 200mm. Gas burner with adjustable air intake.

2.2 Fuel: Gas with purity over 95%.

2.3 Igniter: It is a high-voltage electronic automatic ignition.

3.3 Cover plate: It is composed of heat-insulating asbestos board and steel plate pressed on the asbestos board, and its dimensions are 600 mm in length, 90 mm in width and 10 mm in thickness.

4 Temperature monitoring instrument:

4.1 The flame center temperature is measured by armored thermocouples with an accuracy of class II, type K, and an outer diameter of 2.0 mm. Range 1300°C.

4.2 Temperature record: Imported intelligent P.I.D temperature controller (with automatic calculation function) and high-precision PT100 thermocouple sensor and timer are adopted, with an accuracy of 0.5%±1.

5.Timer: 0~99.99s can be set arbitrarily, resolution: 0.01s, error: 1s/h

6.Automatic buzzer: During the test, an alarm will be issued every 15 seconds to remind the operator to record the current combustion status, and the combustion time lasts for 4 minutes.

7.Test station: 1 station.

8.Sample size: L900*W900 thickness is 5mm, the surface is flat and smooth. The standard requirements that the sample must meet: 1. The asbestos standard plate is 600*90, and the thickness is 6-8mm. 2. The standard board of rubber wood is 600*90, and the thickness is 8-10mm.

9.Gas flow: 860ml/min adjustable.

10.Flame temperature: 900℃±2℃

11.The structure of the instrument consists of two major parts, the main control box and the combustion box. The control box is removable.

12.Combustion box size: 610㎜×250㎜×520㎜.

13.The frame material is welded by high-quality stainless steel, the control box is made of electrostatic steel plate, and the surface is sprayed with plastic, which is more clean and beautiful.

14.The control box adopts a relay control system, and all electronic components are domestic leading brands, which can better guarantee the working performance and detection accuracy of the machine.

15.The equipment has the following safety protection devices: power overload, short circuit protection, control circuit overload protection, and ultra-high temperature protection.

16.Power requirements: AC220 (±10%) V/50HZ

17.The standard board is equipped with:

17.1 Asbestos standard board: the size is 600 mm in length, 90 mm in width and 6 mm to 8 mm in thickness.

17.2 Oak standard board: 600 mm in length, 90 mm in width, 8 mm to 10 mm in thickness, and its air-dry density is (0. 7 to 0. 85) g/cm3.

18.Test substrate: The test substrate is a first-grade five-layer plywood with a thickness of (5±0.2) mm. The test plate is 600 mm long and 90 mm wide. The surface of the test panel should be flat and smooth, without knots and obvious defects.