UL910 Steiner Tunnel Furnace chamber

UL910 Steiner Tunnel Furnace chamber

 

Design referenced to the below standards

 

UL 910 : UL Standard for Safety Test for Flame-Propagation and Smoke-Density Values for Electrical and Optical-Fiber Cables Used in Spaces Transporting Environmental Air

 

2.1 Summary

 

This technical solution is based on the integration of instrumentation and electricity, and uses OMRON's advanced multi-function control system to combine ignition sequence, combustion safety, electrical interlocking, automatic temperature control, manual adjustment, monitoring alarm, and data acquisition / communication into one. The furnace temperature and pressure control system uses the control system composed of OMRON controller + Advantech + Visual Basic software for automatic control and online monitoring. The upper computer Advantech operation station operates and monitors the necessary process parameters of the furnace. It has data storage, inspection and printing. , And other functions. At the same time, according to the requirements of UL910 / NFPA262 standards, a dedicated combustion test room can be set up for combustion test, This combustion test room effectively isolates the Steiner horizontal tunnel furnace,Install the smoke density measuring end in a dark room,Avoid interference from external light；Burn test area, adopt independent design method,according to the standard requirement, should provide free airflow. Therefore, during the entire test, keep the room under controlled air pressure of 0-12 Pa (0-0.05 inch water volume) higher than the surrounding air pressure.,The temperature is maintained at 18.3 ° C-26.7 ° C (65 ° F-80 ° F) and a relative humidity of 45-60%.

 

2.1.1 Design conditions

Furnace type: Steiner horizontal tunnel furnace

Furnace main dimensions: Furnace size 7620mm * 451mm * 305mm

Number of furnace covers: Steiner horizontal tunnel furnace: 1 furnace cover

Furnace working temperature: up to 600 ℃ (flue gas temperature)

Fuel: Methane with a purity of at least 95%

Fuel calorific value: 3500btu / lb

Fuel pressure: 0.4-0.5MPa

Burner model: 3/4 inch U-shaped double burner

Exhaust temperature of flue pipe: <250 ° C, usually the flue gas temperature is controlled within 200 ° C.

Test method of the tested object: Horizontal component furnace-furnace ceiling hoisting

Design conditions 15KVA, 380V/220V, 3 phases. Notes: Voltage can be customized.

2.1.2 Structural parameters

2.1.3 n Furnace structure: refractory brick + SUS304 stainless steel plate

2.1.4 n Furnace bottom structure: refractory brick 229mm x 114.5mm x 64mm

2.1.5 n Type and quantity of burner: 1 3 / 4-inch U-shaped double burner.

2.1.6 n Smoke exhaust method: mechanical smoke exhaust + cold air mixing on the back wall

2.1.7 Furnace door opening method: Horizontal component furnace-hoist ceiling hoisting and translation (customer built)

2.1.8 Furnace diagram

2.1.4 Purpose:

For wire and cable UL910 flammability testing

2.1.5 Design principles

Adopt the principles of advanced technology, reliability, safety, and economic rationality

 

2.2 Furnace structure

 

2.2.1 Furnace Shell

The furnace steel structure is composed of square tube / rectangular tube end, side upright and furnace body steel plate. After being welded with high strength, it forms a solid whole, which can be used without deformation for a long time.

Furnace body steel plate:SUS304,δ=3mm

Furnace frame:Q235-A ,Square tube / rectangular tube

Furnace transverse bars:Q235-A ,Square tube/ rectangular tube

Window:Quartz glass and tempered glass double layer combination,δ=3mm,70mm±6mm×280mm±38mm

 

2.2.2 Furnace Resistance materials

The test furnace masonry is consisted of refractory bricks, At the same time, in order to provide the air turbulence required during the combustion process,Obtained by placing six 229mm long x 114.5mm wide x 64mm thick heat-resistant refractory bricks(Long vertical line of the wall and 114.5mm long parallel line). According to the measured burner centerline to the refractory brick centerline,Refractory bricks near the window (without obstructing the windows) 1.98m±152mm,3.96m±152mm and 5.79±152mm,the distance of another side is 1.37m±152mm,2.90m±152mm and 4.88m±152mm.

The highest Temperature resistance: 1427℃ (2600℉)

Bulk Density: 0.77±0.046g/cm3

Thermal conductivity at average temperature:

260℃(500℉) 0.23W/m·℃

538℃(1000℉) 0.27 W/m·℃

815℃(1500℉) 0.32 W/m·℃

1093℃(1500℉) 0.37 W/m·℃

2.2.3 Furnace door and Pressing mechanism

Operation Furnace door above the furnace body, as a sealing device for the furnace body. Composed of metal and inorganic insulators, Insulators composed of inorganic insulators, 51mm ± 6mm thick inorganic insulator material

Horizontal furnace door is welded by section steel, use self-weight vertical lifting method to compact, to observe the condition of the furnace, observation windows installed on both sides of the furnace wall, to get an effective seal, an effective water seal acts as a seal between the furnace door and the furnace body, Using tap water as the circulating water source can not only provide a seal for the quality inspection of the furnace body and the furnace door, but also take away the heat during the combustion test and effectively protect the furnace body.

The lab should provide the crane to lift the lid.

Max. Effective use temperature up to 1050℃；

Density: 335±5kg/m3;

Thermal Conductivity: 0.085W/mK@400 ℃

Dimension 7620±50mm*451±5mm*305±5mm

2.2.4 Inlet chamber and inlet baffle

The furnace steel structure is composed of square tube / rectangular tube end, side upright and furnace body steel plate. After being welded with high strength, it forms a solid whole, which can be used without deformation for a long time. The air intake baffle is pneumatically controlled and can be opened and closed automatically. Intake chamber This element shall have a rectangular opening of 298.5mm ± 6mm × 464mm ± 6mm to allow air to pass through the nearest baffle into the combustion test chamber.

Furnace steel plate: SUS304, δ = 3mm

Furnace frame: Q235-A, square tube / rectangular tube

Furnace transverse ribs: Q235-A, square tube / rectangular tube

2.2.4 Smoke exhaust system and furnace pressure control system

The exhaust of the furnace body adopts the form of mechanical exhaust to ensure that the pressure and temperature in the furnace and the exhaust gas meet the standard requirements. It includes transition section, smoke exhaust pipeline, automatic butterfly valve, and differential pressure control system. Transition section: a rectangular section stainless steel element with a length of 902mm ± 6mm × 686mm ± 6mm in width × 438mm ± 6mm in height,and a 457mm±6mm It consists of a long rectangular elliptical transitional section, and the rectangular elliptical transitional section is connected to an exhaust pipe with an inner diameter (I.D.) of 406mm ± 3m. The exterior of the transitional section is insulated with a 51mm ceramic fiber cover, with a density of 130kg / m3. The steel plate is SUS304, δ = 1.5mm. Exhaust pipe: 406mm ± 3mm I.D. exhaust pipe, extending from the exhaust end of the transition section from 4.88m to 5.49m to the center line of the smoke measurement system, so as to provide a completely mixed exhaust gas flow. The exhaust pipe opening shall be insulated with a high temperature inorganic material of at least 51mm, from the beginning of the exhaust transmission part to the smoke detection system. The steel plate is SUS304, δ = 1.5mm. Differential pressure control system: The detector should consist of a stainless steel column with a column length rated twice the outer diameter of the column, the length of the draft gauge tap is 25±12mm. 25±12mm, and a central solid partition. The bidirectional probe is connected to a pressure sensor, which can effectively read the pressure value in the furnace.

 

Exhaust damper:406mm I.D. The single-piece pipe flow control damper of the pipe is installed at 1.68m ± 0.15m below the exhaust pipe of the smoke measurement system, and the center line is to the center line.

The relative positions of exhaust transition components exhaust ducts, smoke measurement systems, and exhaust duct dampers are shown in the figure.

In order to maintain control of the air flow during the entire test process, the exhaust pipe damper should be controlled by a closed-loop feedback system that forms effective communication with the differential pressure control system.

2.2.5 Effect drawing:Steiner Tunnel Furnace Chamber

2.3 Burning system

 

2.3.1 Burner

The gas to the burner should be provided by a single inlet duct, Disperse through the T-section to each burner. Elbow tube rated for 19mm (0.75 inch) air outlet, the burner plane should be parallel to the test room floor. This allows the gas to be directed directly up the sample. Each burner uses the 102mm ± 6mm centerline at each side of the centerline of its combustion test chamber to make up positions so that the burner flame is evenly distributed.

Use electronic ignition system to ignite gas stove from a long distance, guaranteed safety performance, High voltage igniter, 44KV, 50mA, minimum voltage of ignition electrode is 1.8kVp.

2.3.2 Valve group

2.3.3.1 Gas pipeline system

Methane with a purity of not less than 95% is sent to the furnace through ball valves, pressure reducing valves, pressure gauges, two solenoid valves, and mass flow controllers.

2.3.3.2 Gas pipeline components:

① Pressure reducing valve:Japan Ito Mirai pressure reducing valve with inlet pressure compensation and zero pressure shutdown,According to the set spring tension. The outlet pressure of the pressure regulating valve remains constant and is not affected by changes in gas flow. When no gas flows through the pressure reducing valve, the regulating valve closes automatically.

② Solenoid valve: open to cut off, quick closing time 1 second, play a fast response and fast cut off. Maximum working frequency: 20 times / minute, maximum working pressure: 360mbar.

③ Pressure switch pressure gauge: measure the pressure of the main gas pipeline, and pave the way for the adjustment of the gas pressure during the commissioning phase, which can ensure that the pressure of the gas pipeline is maintained at a normal level. Pressure range: 0 ~ 20kpa.

④ Mass flow controller: American AALBORG mass flow controller, 316 stainless steel, maximum pressure 1000psig (70bar), leakage rate less than 1 × 10-7 sml / s, calibrated by NIST, 0 ～ 5VDC and 4 ～ 20mA signal, circuit protection, Control speed ≤ 2s, control accuracy is ± 1% FS, repeatability ± 0.5FS, temperature range 0 ～ 50 ℃, humidity range 0 ～ 90%, digital display, gas supply meets 5000Btu (5.3MJ) / during automatic control test Min heat requirement, the software automatically records the amount of gas used; it can cooperate with the burner output standard 5.3MJ / min heat, and according to different standards, the gas flow can be controlled by the mass flow meter, the measurement range is 0 ~ 160L / min, which can change the burner Calorific value output, the maximum output energy can reach 100MJ / min;

⑤Gas filter: Italy Guilong gas filter, filter cotton aperture <50um

 

2.4 Smoke Density Measure System

 

2.4.1 Smoke Density measure system light source

An American GE 12V sealed lamp, clean lens, automatic spotlight mounted on the cross section of the exhaust duct, the light beam should shine upward along the vertical axis of the exhaust pipe, The cylindrical beam should pass through the openings of 76mm ± 3mm in diameter at the top and bottom of the 406mm (16 inch) I.D. pipe, and the combined beams should be concentrated at the center of the photovoltaic cell.

2.4.2 Receiving device for smoke density measurement system

Photocells that output directly according to the proportion of light received should be placed above the light source, and the total distance from the path of the light to the battery is 914mm ±102mm. Photocells should be connected to recording equipment, which is used to show that the incident light in the disappearing smoke is attenuated due to special circumstances and other effects.

2.4.4 Heating curve:Meet the requirements of rising and falling temperature control and furnace temperature deviation.

2.4.5 Furnace pressure and temperature control criteria: Preheating is carried out using a steel plate and a layer of uncoated, fiber-reinforced cement board rated at 6 mm thick x 2.44 m long, wide enough to be placed on the supports of the chamber as shown, with a removable roof in place. The fuel was supplied with methane, adjusted to the required flow rate using a 16mm ± 1.5mm opening in the inlet baffle. Preheating was carried out until the temperature reached 66°C ± 3°C as indicated by the floor thermocouple at 7.09 m ± 13 mm. The combustion test chamber was allowed to cool down when the temperature indicated by the floor thermocouple at 3.96 m reached 41°C ± 3°C.

2.4.6 Air flow velocity: These seven points are determined by dividing the tunnel into seven equal sections and recording the flow velocity at the geometric center of each section. The points are at 7m ± 25mm from the centerline of the gas furnace and 152mm ± 6mm below the plane of the roof support. 1.22m/sec ± 0.025m/sec (4ft/sec ± 0.083ft/sec) flow velocity should be obtained.

Translated with DeepL.com (free version)

2.4.7 Furnace Thermocouple: A 19 AWG nickel-chromium alloy thermocouple at the door with a 9.5mm ± 3mm joint exposed to the combustion chamber air shall be inserted through the floor of the test chamber. The tip of the thermocouple shall be 25.4mm ± 3mm below the top surface of the fiberglass tape, 7.01m ± 13mm from the centerline of the furnace nozzle, and in the middle of the width of the combustion chamber. A 19 AWG nickel-chromium alloy thermocouple embedded 3.2mm ± 1.5mm below the surface of the test chamber floor should be placed 3.96m ± 13mm from the centerline of the furnace nozzle and 7.09m ± 13mm from the refractory cement and in the middle of the combustion chamber width.

Working enviroment

The fire test chamber in which the test chamber and smoke measurement system are located shall be provided with a free-flow condition of air to maintain a controlled pressure in the chamber of 0 to 12 Pa (0 to 0.05 inches of water column) above the ambient air pressure for the entire duration of each test. The temperature shall be 18.3°C to 26.7°C (65°F to 80°F) and the relative humidity shall be 45% to 60%.

 

Air conditioning and humidifying and dehumidifying devices are installed for controlling the indoor temperature and humidity, and temperature and hygrometer are provided for monitoring the indoor environment, as well as atmospheric pressure gauge for monitoring the indoor pressure.

 

1.2 Water, electricity and gas requirements for equipment installation

 

1.2.1 Water requirements

1.2.1.1 Tunnel furnace support cooling: tap water, 0.07mpa

1.2.2 Site requirements

1.2.2.1 Floor space of the tunnel furnace: length not less than 22 meters, width not less than 4 meters, height not less than 4 meters;

1.2.3 Electrical requirements

1.2.3.1 Electricity requirements1: 220V, 50Hz

1.2.3.2 Electricity requirement 2: 380V, 50Hz

UL 910 : UL Standard for Safety Test for Flame-Propagation and Smoke-Density Values for Electrical and Optical-Fiber Cables Used in Spaces Transporting Environmental Air

 

5.2 Technical Parameters:

 

1. meet the requirements of NFPA 262 and UL910 test standards, as well as the data and curves required to be recorded in the standards;

2. smoke density measurement device, deviation of 1%, full-scale fluctuation range of less than 1%, can be confirmed by calibration after the filter;

3. with the air inlet box in the open state, the centrifugal fan airflow can make the static pressure in the static pressure measurement section reach 37pa;

4. with the air inlet box closed, the static pressure rises to at least 93pa;

5. the air velocity in the combustion box can be adjusted to 1.22 m/sec ± 0.025 m/sec; the air velocity must be recorded at seven points, each located 7 m ± 25 mm (23 ft ± 1 in) from the centerline of the gas burner and 152 mm ± 6 mm (6 in ± 0.25 in) below the plane of the top cover support flange. Determine these seven points by dividing the flue width into seven equal segments and recording the air velocity at the geometric center of each segment.

6. an adjustable gas supply of 86 kW ± 2 kW (294,000 ± 7300 Btu/hr); the photocell output, gas pressure, pressure differential across the orifice plate, and volume of gas used shall be recorded continuously at 2-second intervals throughout the test.

7. The temperature rise curve shall be similar to the required curve in the standard, with a deviation of 2% or less;

8. report output of the flame propagation distance versus time graph during the test period

9. the report output of the pipeline velocity graph during the test.

5.3 Acceptance of standard material:

TP149 standard cable is used for acceptance assessment of the equipment, and its recommended results are shown in the table below: