Range

1、 It specifies the inspection procedures, data review, prototype testing, and experiments for intrinsically safe electrical equipment used in explosive environments. This testing implementation rule is a supplement to the requirements of GB/T 3836.4, GB/T 3836.18-2024, and others.
2、 Applicable for the inspection of intrinsically safe electrical equipment used in explosive environments, products such as mining lamps can also be referred to.

Inspection basis

GB/T3836.1-2021 Explosive Atmosphere Equipment Part 1 General Requirements
GB/T3836.4-2021 Explosive Atmosphere Part 4 Equipment Protected by Intrinsic Safety Type "i"
GB/T 3836.18-2024 Explosive Atmosphere Part 18: Intrinsic Safety Systems
GB4208-2017 Degrees of Protection Provided by Enclosures (IP Code)

Inspection Procedure

1. The inspected unit shall prepare technical data related to the explosion-proof performance of the applied product in accordance with the requirements of GB/T 3836.1-2021 (the enterprise commission shall have a commission form signed by the enterprise legal representative, and the safety standard commission shall have a safety standard technical review task book); Registration in the Traffic Center Business Office;
2. The business room will submit the received technical data and receipt to the explosion-proof room, and issue a technical review task book at the same time;
3. After receiving the information, the explosion-proof room will be registered by a dedicated person and posted on the intranet. All authorized personnel can download it from the internet; After the chief examiner receives the task and fills in the relevant information, they return it to the data receiver for summarization. The technical data registration form should reflect all time nodes to facilitate task monitoring.
4. Task distribution: Routine tasks are registered and completed by the data receiver, and then handed over to the director of the technical review room for arrangement of the chief examiner. Import or other special tasks shall be arranged by the director or deputy director of the explosion-proof room. The time should not exceed 24 hours.
5. Review method: The review adopts a two person review method that combines primary review and secondary review.
6. The deadline for review is divided into three categories: simple, general, and complex drawings and materials. Simple information generally takes no more than 0.5 working days, general information review takes 1 working day, and complex information takes 2 to 3 working days. The specific time limit shall be proposed by the task distributor.
7. After receiving the technical materials, the chief examiner shall make a review plan according to the requirements of the review commissioning unit, and conduct the review based on standards such as GB/T 3836. The review content includes product standards, drawings, user manuals, detailed lists of controlled components, calculation sheets, and more
Technical materials related to explosion-proof review, such as material inspection reports, should be reviewed and recorded. After the initial review is completed, it shall be submitted for review and inspection. The verification personnel shall fill out the verification record form. After the review personnel have no doubts, the chief examiner shall promptly notify the inspected unit of the review opinions and record the contact information, contact person, and main matters in the memo card. Communication with clients should be prepared in advance, and all issues should be reported at once with written records.
8. After verifying the modified technical data, the reviewing personnel should promptly arrange for a re examination and keep records upon receiving the modified data from the inspected party. For issues that still do not meet the requirements after modification, timely feedback should be given to the inspected party and the processing time and nature of the problem should be recorded in the memo card, which belongs to those that have not been modified properly or those that have been modified. The modification process may be repeated multiple times, but the reviewer must clearly record the processing time nodes and main matters in the memo card; For materials that have been modified more than twice but still fail, they should be reported to the inspection room.
9. The paper materials are reviewed and approved, and after confirmation and signature by the reviewing personnel, the drawings are stamped. The stamping of the drawings is completed by the reviewing personnel, and only the materials involved in the review process are stamped. Unrelated drawings do not need to be stamped;
10. After the stamping is completed, one copy of the documents shall be handed over to the inspected unit, and the other copy shall be temporarily stored by the reviewing personnel. After the test is qualified and the certificate is issued, it shall be archived and kept together with the inspection report and explosion-proof certificate.

11. For the technical data review of products entrusted for sample submission for the first time, modifications can be proposed in conjunction with product inspection. However, all technical review work should be completed before issuing the report and certificate of conformity. The review records should be filled out completely, signed, and the drawings should be stamped and delivered to the inspected party.

12. Prototype testing and experimentation shall be carried out in accordance with the relevant regulations of the center

Technical review
Technical review includes standard review, drawing review, user manual review, and review of explosion-proof related materials provided by the enterprise. Devices that only use semiconductors and controllable semiconductors for current limiting protection cannot be classified as "ia" level.

Equipment Description
Technical review should specify the explosion-proof type and working principle of the equipment; Please describe the power supply method of the equipment, including wireless, infrared, laser, ultrasonic, etc; If it is a product change, list the changes and how the changes affect the explosion-proof performance.

Final assembly drawing
Complies with the provisions of GB4457-4460 "Mechanical Drawing". The overall plan should reflect the basic structural characteristics of the product, including a detailed list of parts, external dimensions, markings, and identification; The technical requirements should include the following: reference standards, requirements for shell protection level; Requirements for surface insulation resistance (if any); Working voltage, working current; The electrical clearance and creepage distance of intrinsic safety terminals, as well as the spacing between intrinsic safety terminals and non intrinsic safety terminals.
Special attention should be paid to:
a) The metal content of the metal shell and metal components of the shell shall meet the requirements of GB/T 3836-1-221 (with particular attention to the requirements for lightweight alloys; Class I portable instruments, lamps, and electric drills shall be made of lightweight alloys that meet the friction spark test method specified in GB/T13813-2008, and Class II EPL Ga and EPLGb requirements); Non metallic materials have a surface area size and surface insulation resistance of<1G Ω.
b) If it is a series of products, the differences between each model of product and their impact on explosion-proof performance should be explained in detail, and relevant drawings should be attached.
c) If other explosion-proof types are included in the composite product, corresponding drawings should be attached. If there are certified explosion-proof components in the system, the model name/explosion-proof mark and explosion-proof certificate number should be marked, and a copy of the explosion-proof certificate should be attached.

Mechanical structure diagram
The product should have shell drawings, sealing strip drawings, and wiring terminal diagrams;

POS machine gas and dust detector explosion-proof mobile phone

Electrical schematic diagram
Review the components or circuits in the electrical schematic that affect the intrinsic safety performance, and provide specific descriptions according to the provisions of GB/T 3836.4. Confirm the intrinsic safety parameters (voltage, current, inductance, and capacitance), record and analyze them, and evaluate them.
If there are both intrinsic safety circuits and non intrinsic safety circuits in the circuit, intrinsic safety circuits need to be marked with dashed boxes.
If the circuit or device is sealed to meet the requirements, the sealed part should be marked with a dashed box and a sealing process document should be provided.
a) Reliable components:
Transformer, current limiting resistor;
——The structure of the transformer shall comply with the requirements of GB/T 3836.4-2021; If it is a power transformer, its primary should have fuse protection; The transformer should provide a structural diagram of the transformer (special attention should be paid to marking the thickness of the shielding layer, winding spacing, thickness of the solid insulation layer, and the withstand voltage requirements between each winding, etc.)
——Current limiting resistors can only be thin film, wound, or printed resistors;
b) The rated values of components related to intrinsic safety shall meet the requirements of GB/T 3836.4;
——Current limiting resistor;
——DC/DC power chip;
——Sampling comparison circuit in semiconductor current limiting circuit, MOS transistor, transistor;
——Zener diodes and thyristors in semiconductor voltage limiting circuits;
——The switch chip in the switch power supply circuit.
c) Evaluation of pure resistance circuit: Calculate whether the current under the corresponding voltage in the circuit meets the requirements of GB/T 3836.4.
d) Evaluation of capacitance: Calculate the maximum capacitance of each voltage level under technical and non-technical fault conditions of ia and ib, and evaluate it according to the curve or table in the appendix of GB3836.4, with a safety factor of 1.5 applied during evaluation. When capacitors are used according toGB/TWhen the safety factor is improved by series resistance in Appendix F of 3836.4, the resistor and capacitor should be encapsulated as a whole;
e) Evaluation of inductance: The maximum (equivalent) inductance value of the induction is calculated based on the corresponding explosion-proof level (ia, ib) for technical and non-technical faults, and the current on the inductance is calculated
Formula for calculating energy, usingGB/TEvaluate the energy given on the curve in Appendix 3836.4; When evaluating, apply a safety factor of 1.5. When the inductor is connected in parallel with the diode, the inductor must be encapsulated as a whole with the diode; Special attention should be paid to the applicability of sealing for rotating motors to prevent ignition of shaft end clearances.
f) Isolation device:
——Transformer;
——Optocoupler;
——Relay;
——Capacitors (IA protection level requires 3 capacitors to be connected in series, IB protection level requires 2 capacitors to be connected in series);
Note: In addition to meeting the requirements for voltage resistance, the spacing between optocouplers, relays, and capacitors must also meet the requirements of Table 5 of GB3836.4.

Printed board diagram
Confirm the voltage, current, inductance, and capacitance involved separately for the printed circuit board and component installation diagram combined with the component list.
The printed layout should record the following information
——The printed board diagram should be consistent with the actual product.
——Technical requirements should include dimensions such as printed board thickness, conductive film thickness, printed line width, and board line spacing;

Battery
The review of batteries and battery packs should record the following information:
a) Battery and battery pack structure type: sealed or shell sealed;
b) Maximum open circuit voltage of the battery: compliantGB/T3836.1 When specified in Tables 10 and 11, take the voltage from the tables. Batteries not listed in Tables 10 and 11 shall be treated as loose components, and the maximum open circuit voltage shall be determined by testing at 10.5. The nominal voltage shall be taken from the specified value of the battery manufacturer.
c) Internal resistance of batteries and battery packs: The internal resistance of batteries and battery packs should be determined according to 10.5.3. If a current limiting resistor is used to limit the current that the battery pack may generate, its rated value should meet the requirements of 7.1.
Note 2: When it is necessary to use a current limiting device to protect the output safety of the battery pack, it is not required to use the current limiting device as an integral component of the battery pack.
d) Current limiting device:
——When the battery pack is intended for use and replacement in explosive environments: the battery pack should form a replaceable component with the current limiting device. The unit components should be encapsulated or sealed, and only the intrinsic safety output terminals and appropriately protected charging intrinsic safety terminals (if provided) can be exposed.
——The battery pack should not be replaced in explosive environments: The battery or battery pack can be installed according to the requirements for the intended use and replacement of the battery pack in explosive environments, or it can be installed in a device withGB/TInside the cavity of special fasteners specified in 3836.1.
e) Connection method: The layout of the battery, battery pack bracket, or device connection method should ensure that the intrinsic safety performance of the device is not compromised during installation and replacement of the battery or battery pack.
f) Handheld or portable electrical equipment: For complete handheld or portable electrical equipment, it should undergo the drop test specified in Article 26.4.3 of GB3836.1. If there is no detachment or separation of the battery pack that causes the intrinsic safety performance of the equipment or battery to fail, the equipment structure is considered qualified.
g) Warning signs: The equipment should have warning signs as specified in GB3836.1, Article 29.11.
h) With external charging contacts: For batteries or battery pack components with external charging contacts, measures should be taken to prevent short circuits or to prevent single cells and battery packs from releasing enough energy to ignite when any pair of contacts may accidentally short circuit. Blocking diodes or series reliable resistors should be used.
Note: The highest voltage Um that may be applied to these charging contact connections should be marked on the equipment and can be controlled
As shown in the diagram.
i) Battery structure
The spark ignition ability and surface temperature of batteries and battery packs should be tested and evaluated according to the provisions of 10.4.3.
The structure of batteries and battery packs should be sealed (airtight) batteries and battery packs, valve controlled sealed batteries or battery packs, batteries and battery packs with pressure release devices, and sealed in the same way as the previous item.
These batteries or battery packs should not require electrolyte replenishment throughout their entire lifespan and should have metal or plastic sealed casings that meet the following requirements:; No need to verify that the battery or battery pack meets the manufacturer's technical requirements.

Components with loose regulations
For components with loose regulations, ten unused component samples should be taken from any source or several sources to measure their relevant parameters. Usually, the test should be conducted at the specified maximum ambient temperature (e.g. 40 ℃), or based on the maximum ambient temperature. But when necessary, temperature sensitive components (such as nickel cadmium batteries/battery packs) should be tested under low temperature conditions to obtain their most unfavorable conditions.
Different parameters can be taken from different samples, and the representative parameters of the component should be the most unfavorable values obtained from testing 10 samples.
Unrestricted components refer to components without standards or with incomplete parameters despite having their own standards; These parameters are essential for evaluating the intrinsic safety performance of the device.

Component List
The component list should be verified to be consistent with the electrical schematic, and the part numbers, drawing numbers, rated values, production units, etc. of the components should be clearly defined.

Nameplate
The drawing should specify the material of the nameplate and the method of pasting; The nameplate content should include: explosion-proof mark, working voltage, working current, intrinsic safety parameters, safety label number, explosion-proof certificate number, and production date.

Enterprise standards
The review of enterprise standards should pay attention to the following points
——Reference standards: GB3836, GB4208-2008, etc
——Explosion proof type and explosion-proof mark of the product
——Product usage environment
——Product testing requirements and testing methods
a) Intrinsic safety parameter testing:
b) Shell protection level test
c) Measurement of electrical clearance and creepage distance
d) Spark ignition test
e) Dielectric strength test
f) Maximum surface temperature test
g) Insulation resistance test on the surface of the shell
h) Battery leakage test
i) Explosion proof drop test
j) Isolation device withstand voltage test
k) Routine and type tests of transformers;

an instruction manual
The review of the user manual should pay attention to the following points
——The cover should have a reference standard GB 3836
——Explosion proof type and explosion-proof mark of the product
——Product usage environment
——Product intrinsic safety parameters
——Safety warning language, warning language

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