GB/T 20702-2026Test method for the extinguishing performance of gaseous extinguishing agents (English PDF)

4.2 Test Apparatus

4.2.1 General Requirements The extinguishing agent concentration testing device is a cup burner. The cup burner should conform to the structure shown in Figure 1, and the combustion cup should conform to the structure shown in Figure 2. Structure. Unless otherwise specified, the dimensional error of the indicated dimensions shall not exceed ±5%.

4.2.2 Components The test setup includes the following.

---Combustion cup. Should be cylindrical, open at the top, made of glass, quartz, or stainless steel, with an outer diameter of (30±1) mm and a wall thickness of 1 mm. 2mm; top edge chamfered at 45°, fuel temperature measuring device installed 2mm~5mm below the top; gaseous fuel fire extinguishing The top of the device should be designed to ensure uniform gas flow (e.g., by filling it with refractory material).

---Chimney. Should be a vertical circular pipe, made of glass or quartz, with an inner diameter of (85±2) mm, a wall thickness of 2 mm~5 mm, and a height of... (535±5)mm.

---Gas collection tube. Air and extinguishing agent are collected in the gas collection tube to form a single mixed flow that is then sent into the diffuser.

---Diffuser. Installed at the bottom of the chimney, it is used to introduce a mixed airflow of air and extinguishing agent, and to ensure that the mixed airflow passes evenly through the chimney. The temperature of the air and extinguishing agent mixture inside the diffuser should be (25±10)°C, measured using a calibrated temperature sensor.

---Fuel supply. Liquid fuel shall be delivered to the cup at a constant and adjustable level; gaseous fuel shall be delivered to the cup at a constant flow rate.

---Air supply. A device for supplying air to the air collection pipe. The flow rate is adjustable, and the air flow rate should be measured using a calibrated device.

---Extinguishing agent supply. A device for delivering extinguishing agent to the gas collection pipe. The flow rate is adjustable, and the extinguishing agent flow rate should be measured using a calibrated device.

---Delivery system. A representative and measurable extinguishing agent sample should be delivered to the cup burner in gaseous form.

4.2.3 Delivery system suitable for testing the extinguishing concentration of high-boiling-point gas extinguishing agents Before introducing high-boiling-point gaseous extinguishing agents, the equipment should be adjusted, and a delivery system suitable for high-boiling-point gaseous extinguishing agents should be added to ensure the extinguishing effect. The extinguishing agent is fully vaporized. A schematic diagram of the extinguishing agent delivery system is shown in Figure

3.The design of the delivery system should ensure that the extinguishing agent can vaporize and remain stable. The extinguishing agent should be delivered to the cup burner in a controlled manner, and the temperature should be strictly controlled to avoid high-temperature decomposition of the extinguishing agent or the generation of impurities, which would affect the test results. The components of the conveying system are as follows:

---High-pressure syringe pump. Composed of a motor, transmission system, syringe, and control system, it works in conjunction with a check valve to seal the liquid inlet, forming a closed-loop system. The system ensures that the liquid extinguishing agent is output at a constant flow rate under high pressure.

---Vaporization Furnace. Utilizes a circulating tank heating method to vaporize liquid extinguishing agents. The vaporization furnace should be equipped with precise temperature control to ensure... The extinguishing agent is completely vaporized and the temperature is stable.

4.4 Test Procedure

4.4.1 Using flammable liquids as fuel The test procedure for determining the extinguishing concentration of a gaseous fire extinguishing agent using a flammable liquid as fuel is as follows:

a) Transfer the flammable liquid from the fuel tank into the combustion cup.

b) Start the heating device to bring the fuel temperature in the cup to (25±3)°C or above the open cup flash point (5±3)°C, whichever is higher. Flash point determination shall comply with the provisions of GB/T 3536.Adjust the liquid level in the combustion cup to ensure that the fuel level is above the temperature measuring device. The distance from the top of the cup is 5mm to 10mm.

c) Adjust the airflow to 40L/min.

d) Ignite the fuel and pre-ignite for 60s~120s, while adjusting the fuel level to be no more than 1mm from the top of the cup.

e) Introduce the extinguishing agent, gradually increasing the flow rate until the flames are extinguished. Record the flow rates of the extinguishing agent and air, or the air/extinguishing agent flow rate in the chimney, during extinguishing. Oxygen concentration in the extinguishing agent mixture. After adjusting the extinguishing agent flow rate, it should stabilize for at least 10 seconds to allow the new proportion of extinguishing agent in the gas collection pipe to reach the target concentration. The extinguishing agent and air should reach the combustion cup. The increase in extinguishing agent flow rate should not exceed 3% of the initial flow rate. Approaching the extinguishing point... At this time, the increase in extinguishing agent flow rate should be as small as possible. The final flow rate adjustment should be the smallest unit of measurement on the measuring device.

f) Calculate the extinguishing concentration of the extinguishing agent in accordance with the provisions of 4.4.3.

g) Remove fuel and all residues adhering to the combustion cup, as well as soot from the combustion, from the combustion cup in preparation for subsequent tests.

h) Repeat steps 4.4.1a) to 4.4.1g) for a total of 5 tests.

i) The average value of the 5 tests is taken as the extinguishing concentration of the extinguishing agent.

4.4.2 Using combustible gas as fuel Combustion cups used for gaseous fuels should achieve a uniform airflow at the top of the cup. For example, combustion cups for liquid fuels are filled with refractory material. The test procedure for determining the extinguishing concentration of a gaseous fire extinguishing agent using combustible gas as fuel is as follows:

a) The gaseous fuel shall be supplied through a calibrated regulating device that allows for adjustment and measurement of the gas flow rate.

b) Adjust the air flow rate to 40 L/min.

c) Pass the gaseous fuel into the cup and ignite it. Adjust the fuel flow rate so that the flame height reaches about 80 mm and pre-ignite for 60 seconds.

4.4.3 Calculation Method for Extinguishing Agent Concentration

4.4.3.1 Concentration Calculation Method The concentration of extinguishing agent vapor in an air/extinguishing agent mixture that just extinguishes a flame is determined using a method specific to the concentration range of the mixture being tested. A calibrated gas analysis device, which can be either a type with continuous sampling capability (such as an online gas analyzer) or a device that has been used for [specific purposes]. For analyzing discrete samples (such as gas chromatographs), continuous measurement techniques are preferable. A continuous oxygen concentration analyzer can also be used to measure the oxygen concentration in the air/extinguishing agent mixture in the chimney. Record the fuel flame. The oxygen concentration at the time of extinguishing is used to calculate the extinguishing agent concentration using formula (1).

4.4.3.2 Flow Calculation Method The concentration of extinguishing agent in the extinguishing agent-air mixture can also be calculated by measuring the flow rates of the extinguishing agent and air. If using mass... The mass flow rate measured by the flow meter can be converted into volumetric flow rate using formula (2).

4.5 Test Report The results report should include the following.

a) Equipment diagram, including dimensions and description of materials used.

b) The source and composition of extinguishing agents, fuels and air.

c) Test conditions, including the following. 1) Atmospheric pressure; 2) Laboratory temperature or air temperature entering the bottom of the chimney (if different); 3) Humidity of the air supplied to the chimney.

d) The fuel temperature at the start of each test, the fuel temperature at the time of extinguishing, and the air/extinguishing agent mixture temperature at the time of extinguishing. temperature.

4.4.3.2 is used, record the extinguishing agent and air flow rate during extinguishing; if method

4.4.3.1 is used, record the extinguishing... The concentration of the extinguishing agent and the oxygen concentration at that time.

f) Test the extinguishing concentration of high-boiling-point gas extinguishing agents, and provide a detailed process of vaporization of the extinguishing agent sample.

g) Methods for determining extinguishing concentration.

h) The concentration of the extinguishing agent during each fire extinguishing test, and the type of flammable liquid or flammable gas.

i) Measurement error analysis.