1. Verification ①: Explosion-Proof Certificate (Ex Certificate) (First Check: Authenticity)
Every explosion-proof distribution box must have anExplosion-Proof Certificate, issued by a national-level explosion-proof testing authority. Key verification points:
- Theproduct model and explosion-proof marking (e.g., Ex d IIB T4 Gb)on the certificate must exactly match what you are buying;
- The certificate must bewithin its validity periodand not voided due to structural changes;
- The certificate number can be verified on the issuing authority's official website— call or verify online to prevent forgery and number reuse.
2. Verification ②③: CCC Compulsory Certification + Type Test Report (Nationally Mandated)
Explosion-proof electrical equipment is included in the CCC Compulsory Certification Catalog:
- CCC Certificate: Search by certificate number on the National Certification and Accreditation Information Public Service Platform. The manufacturer name must match the business license and contract entity;
- Type Test Report: Issued by an explosion-proof quality inspection body. The enclosure material, flameproof parameters, and temperature class in the report must match the certificate and the nameplate across all three;
- Watch for cases where the "certificate holder ≠ manufacturer" — OEM labeling is common, so always confirm the actual manufacturer holds complete qualifications.
3. Verify items ④⑤: Nameplate consistency + production equipment (What to look at on-site)
Nameplate consistency: After delivery, check that the explosion-proof marking, certificate number, product model, and rated parameters on the nameplate match the certificatecharacter for character. On cast aluminum enclosures, the nameplate should be cast in or riveted — not a sticker.
Production equipment: On-site, focus on flameproof surface machining — the flange face'sflatness and surface roughnessare ensured by CNC machining equipment. Check whether machining centers / fine milling equipment, hydrostatic test rigs, and flameproof parameter gauges are all in place. Be highly wary of any "explosion-proof factory" that only has sheet metal bending machines.
4. Verify item ⑥: Documentation with shipment and after-sales support (No loose ends at delivery)
- Documentation package with shipment: Copy of explosion-proof certificate, copy of 3C certificate, factory inspection report, installation and operation manual, single-line diagram;
- Factory inspection: Flameproof enclosures should undergo hydrostatic testing per unit or per batch, with traceable reports;
- After-sales terms: Specify the warranty period (typically 1–3 years) and repair support for flameproof surfaces and sealing gaskets;
- Engineering capability: Can they produce a solution based on actual site conditions (zone, gas group, number of circuits), rather than just selling stock?
5. Three pitfalls to avoid (Spotting the tricks)
① Quoted price more than 40% below peers— most likely uncertified enclosures or refurbished boxes. Verify certification before discussing price; ② Borrowed / affiliated certificates— the certificate holder and the contract party don't match, so liability cannot be enforced if an accident occurs; ③ "Modify by drilling holes as needed"— drilling holes or relocating cable gland entries on an explosion-proof box on-site destroys its explosion-proof performance. Reputable manufacturers only build to certified drawings.
FAQ FAQ
Can an explosion-proof distribution box be used without an explosion-proof certificate?
Absolutely not. Using uncertified products in hazardous areas is a violation, and if an accident occurs, the buyer bears legal liability as well.
How do you verify a 3C certificate?
Search on the National Certification and Accreditation Information Public Service Platform bycertificate number or company name. The certificate status should show "Valid" and the product category must match.
Can you buy OEM-labeled explosion-proof boxes?
You need to distinguish: the certificate states theClear manufacturing plant / OEM relationship, complete documentationOEM branding is legal; simply putting a trademark on a product without the manufacturing plant's qualifications is borrowed-certificate supply and is not recommended for procurement.
What is the typical warranty period for explosion-proof distribution boxes?
Typically 1–3 years, with wear parts (seals, indicator lights) typically covered for 1 year. It is safer to write flameproof surface repair support into the contract at signing.
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