Utilizing the Needle Flame Test Apparatus for Accurate Needle Flame Testing

I. Application scope of needle flame test apparatus:
The needle flame test apparatus is suitable for the research, production and quality inspection of lighting, low voltage appliances, household appliances, machine tool electrical appliances, motors, power tools, electronic instruments, electrical meters, electrical connections, accessories and other electrical and electronic equipment, as well as for the simulation of small flame ignition sources in the insulation material, engineering plastics or other solid combustible materials industry.

According to IEC60695-2-2, IEC60695-11-5 and GB/T-5169.5, LISUN ZY-3/ZY-3S needle flame test equipment is applied in the production and quality control department of lighting products, hyperpiesia electrical apparatus, domestic appliance, machine electric appliance, electrical machine, power tool, electronic instrument, electrician instrument and technical equipment. Also, the apparatus is fit for the industry of insulation material, engineering plastics and solid combustible material.

II. Needle flame test apparatus principle:
The needle flame test apparatus is a regular scale (Φ0.9mm) needle-shaped burner, using a special gas (butane), applied to the specimen at 45° angle, to determine the ignition hazard of the small flame formed by the fault condition inside the equipment according to whether the specimen is ignited and the burning time and burning length.

III. Method of needle flame test:

1. Unless specified by the relevant regulations, the test sample shall be placed in the orientation most likely to catch fire during normal use for testing. The fixing method of the test sample shall not affect the test flame or flame extension effect, which should be the same as the normal operation condition.

2. The application of the test flame shall be applied to the outer surface of the test sample which is easy to be affected by the flame, which is caused by normal operation or fault conditions. The orientation of the flame test is shown in Figure 1 (b) and Figure 1 (c). The relevant specifications shall specify the duration of the test flame application. According to GB7000.1-2007 13.3.1, the test flame shall be applied to the point on the sample where the highest temperature may occur, for 10s.

The test flame should make the top of the flame touch the outer surface of the test sample. The test flame should be removed after the prescribed time. If the molten material drops during the flame application, the burner shall be maintained at an angle of 45° with the vertical line to avoid the material from dropping into the tube of the burner, and the center of the top of the burner shall be 8 ±1mm away from the other part of the test sample, and any molten material string can be neglected. When the relevant specification requires more than one point test on the same test sample, attention must be paid to ensure that the degradation caused by the previous test will not affect the results of the later test.

3. Unless specified by the relevant regulations, the experiment shall be carried out on three test samples. According to GB7000.1-0.4, the test in GB7000.1 is a pilot test, generally selecting a lamp sample for the test.

4. Investigation and measurement, if the test sample and/or the underlying layer and/or parts around it are ignited, the burning time (tb) shall be measured and recorded. The burning time refers to the time from the moment when the test flame is removed from the test sample to the moment when the flame is extinguished, and the flame or heat of the test sample and its surrounding parts can no longer be seen.

5. Test results identification, unless specified by the relevant regulations, if the test sample meets one of the following conditions, it can be tested by needle flame.
① The test sample does not produce flame and heat, and the underlying layer or packing tissue paper does not ignite.
② After the removal of the needle flame, the flame or heat of the test sample and its surrounding parts lasted for no more than 30s, tb & lt; 30s, and the surrounding parts did not last for full combustion and the underlying layer or packing tissue paper did not ignite.

IV. Calibration items and calibration methods:
Calibration items: box scale, burner scale, burner skew viewpoint, timer, flame ruler and temperature meter.The calibration items can be selected according to the actual situation and customer requirements. Calibration method:

(1) Visual inspection: visually inspect the appearance and parts for damage and cleanliness, and the equipment can work normally.

(2) Basic scale: the volume of the experimental box is measured by steel tape for length, width and height, and the scale of flame burner and flame height ruler is measured by needle gauge and dial caliper, and the deviation of burner should be adjustable from 0-45°, measured by universal level ruler.

(3) Timer calibration: use electronic chronometer separately to calibrate 10s,20s,30s,60s,120s five calibration points for flame application, and calibrate 30s calibration point for flame holding. The temperature timer is calibrated at 23.5s.

(4) Temperature meter calibration: place the copper block of the connected thermocouple and the standard platinum resistor in the hole of the multi-function temperature calibrator, as close as possible to the bottom of the hole, separately set the multi-function temperature calibrator at 100 °C and 700 °C. After the temperature reaches stability, read the temperature display value of the temperature system three times, and take the average value as the actual display value of the temperature system.

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