BKI intrinsic safety circuit spark test device

1、 Main technical indicators of spark test device

1. The main scope of application of the standard spark test device is:

The test current shall not exceed 3A;

For inductive circuits, the electrical induction is not greater than 1H;

The open circuit voltage for resistive and capacitive circuits shall not exceed 300V.

2. Sensitivity: At a voltage of 24 V, inductance of 90 mH~100 mH, corresponding explosive gas and air mixture, and at the corresponding calibration current, the main electrode should ignite within 400 revolutions;

3. Stability: Conduct 5 consecutive tests according to the sensitivity test conditions, and ignite each time. The experimental device can maintain its sensitivity even after thousands or even tens of thousands of spark tests;

4. Repeatability: that is, after the contact of the test device is damaged, replacing it with a new contact can still meet the requirements of sensitivity and stability;

5. Experimental environmental conditions:

Temperature: (20 ± 5) ℃

Humidity: ≤ 95% RH

Atmospheric pressure: 86 kPa~110 kPa

6. Judgment criteria:

DC: 400 rpm without ignition (about 3200 sparks) is qualified;

Communication: Failure to ignite at 1000 revolutions per minute is considered qualified.

2、 Explosion proof container cover for spark test

1. Organic glass explosion-proof container cover, used for spark ignition test of explosive test mixed gases such as methane, propane, ethylene, acetylene, hydrogen, etc. formed with air;

2. The volume should be at least 250cm3;

3. The thickness of the glass explosion-proof container is about 10mm;

4. Capable of withstanding an explosion pressure of at least 1.5 MPa.

3、 Spark ignition electrode equipment

1. One of the contact electrodes is composed of a rotating electrode disk with two grooves; The other contact electrode is composed of four tungsten wires fixed on a pole holder (made of brass or other suitable metal). The rotating pole grip allows the tungsten wire to slide on the slotted partition;

2. The tungsten wire electrode is composed of four tungsten needles with a free length of 11 mm and a diameter of 0.2 mm uniformly fixed on the four corners of a 38 mm × 38 mm tungsten needle fixing disk. It rotates at a speed of 80 r/min (driven by a motor to rotate the electrode holder);

3. The cadmium disk electrode consists of a 30 mm diameter and two symmetrical grooves with a depth of 2 mm and a width of 2 mm. The distance between the two grooves is 13 mm, and it rotates in the opposite direction relative to the tungsten needle fixed disk at a speed of 19.2 r/min;

4. The horizontal distance between the cadmium disk and the tungsten needle fixing disk is 31mm. The two shafts are insulated from each other and the test device chassis. The two shafts are combined by non-conductive gears with a gear transmission ratio of 50:12. The two shafts are driven by gears to form an ignition device;

To record the number of revolutions of the motor driven pole grip shaft, a counter should be equipped; And when the explosive mixture is ignited, it has the function of automatically stopping the dragging motor or the counter to stop counting.

4、 Calibration test device (circuit)

1. In order to ensure the accuracy of the detection, the sensitivity of the spark test device should be calibrated before and after each test, and the calibration circuit parameters should comply with the provisions of Table 7 of GB3836.4-2000. If the device is qualified, connect the tested circuit and perform intrinsic safety performance testing on the tested circuit;

After the spark test device is filled with the specified test gas, it should rotate no less than 400 revolutions and no more than 440 revolutions when connected to the positive electrode. If the explosive mixture ignites at least once, the sensitivity of the device is considered qualified.

5、 Spark test automatic control valve system

1. The automatic control valve system for spark testing is a supporting device for spark testing, consisting of an automatic valve control system, an electrical control console (with manual and automatic functions), a computer-controlled spark testing system, and other parts;

2. The automatic gas distribution control system mixes methane, propane, ethylene, acetylene, hydrogen, and air through a flow controller, and is equipped with a gas analyzer for real-time sampling and display of concentration values. The microcontroller is used to automatically adjust and control the flow controller to maintain stable concentration of explosive gas mixtures, in accordance with the requirements of GB 3836.4-2000 item 10.2 for explosive gas mixture concentration. The concentration of explosive mixture gas with a safety factor of 1.5 times as the spark test mixture gas meets the requirements of Table 8 of GB 3836.4-2000;

3. The automatic gas distribution device includes gas tanks, valves, pressure reducers, flow controllers, mixing tanks, pneumatic solenoid valves, vacuum pumps, air compressors, fuses, flow controllers, explosive gas distribution devices, binary gas distribution devices, microcontrollers, and outlet valves. Equipped with automatic fault alarm and diagnosis functions, as well as gas concentration display functions;

4. Computer controlled spark testing system: a single-chip microcomputer controlled automation system with peripheral equipment for spark testing devices. It can measure parameters such as voltage, current, arc shape, temperature, etc. during spark explosion, and can automatically collect, store, display, and print the above parameter curves.