ATEX-approved hoses and TRGS 727 compliance
NORRES BAGGERMAN has tested 34 different spiral hose series for their electrostatic properties for use in hazardous areas. The test report was issued on 13 July 2016 in accordance with DIN EN 10204–2.1 and documents which hoses meet the ATEX 2014/34/EU and TRGS 727 requirements when properly grounded.
Hoses in hazardous areas
The ATEX directive (2014/34/EU) regulates products for use in explosive atmospheres. Hoses are not in themselves "equipment" or "components" as defined in the directive — this is stated explicitly in the NORRES BAGGERMAN test report. But hoses must be compatible with ATEX zones by having sufficient electrical conductivity so that static electricity does not accumulate and trigger an ignition energy in an explosive dust or gas atmosphere.
TRGS 727 (Technische Regeln für Gefahrstoffe) is the German technical rule that specifies resistance limits for hoses used to transport flammable media. It builds on top of the ATEX directive and is the standard the NORRES BAGGERMAN test report references.
ATEX zones — what do 0, 1, 2, 20, 21, 22 mean?
The zone classification falls into two groups depending on whether the medium is gas/vapour or dust:
| Zone | Medium | Occurrence of explosive atmosphere |
|---|---|---|
| Zone 0 | Gas / vapour | Continuous or long-term |
| Zone 1 | Gas / vapour | Occasional during normal operation |
| Zone 2 | Gas / vapour | Rare and short-term |
| Zone 20 | Dust | Continuous or long-term |
| Zone 21 | Dust | Occasional during normal operation |
| Zone 22 | Dust | Rare and short-term |
Resistance limits for hoses per TRGS 727
TRGS 727 divides hoses into three resistance classes based on their surface resistance:
- Conductive hose — surface resistance below 106 Ω. Used where high energy accumulation can occur (Zone 0, Zone 1, Zone 20, Zone 21).
- Antistatic hose — surface resistance below 109 Ω measured between two grounded hose ends. Covers Zone 22 (dust) and Zone 2 (gas) when correctly installed.
- Insulating hose — above 1012 Ω. Used exclusively outside ATEX zones.
In all cases there is one prerequisite: the hose must be grounded for the resistance to actually make a difference. That connection is often the weakest link — we have written a separate article on why grounding on AS hoses is critical.
NORRES BAGGERMAN tested hoses
The test report covers 34 spiral hose series from five main families. The table below summarises the six application areas the test report categorises — for the complete overview with article numbers and specific zone approval per hose, please refer to the PDF report itself.
| Hose family | Examples | Typical zone application |
|---|---|---|
| AIRDUC® PUR (AS / EC / FOOD-AS) | AIRDUC PUR 350 AS, 351 EC, 355 AS, 356 AS, INOX FOOD-AS | Pneumatic dust transport (Zone 20, 21, 22), aspiration |
| PROTAPE® PUR / PE | PROTAPE PUR 330 AS, PE 322 EC, PUR INOX 330 FOOD AS | Aspiration (no zone or Zone 22 inside the hose), pneumatic transport |
| NORPLAST® PUR / PVC C | NORPLAST PUR C 385 AS, 386 AS, 387 AS, PVC C 389 AS Superel. | Pneumatic dust transport, aspiration |
| BARDUC® / TIMBERDUC® PUR | BARDUC PUR-INOX 382 FOOD-AS, TIMBERDUC PUR 531/532/533 | Food-compliant dust, abrasive dust |
| CP series (chemical) | CP PE 457 EC1, CP VITON 459 EC1, CP PTFE INOX 475 EC1, CP PVC 465 EC | Transport of flammable liquids (Zone 0, 1, 2 inside), Zone 1/2 outside |
| EVA / Metal hoses | EVA 373 AS, EVA 373 EC, metal spiral hoses | Aspiration, high temperature in ATEX areas |
Requirements for pneumatic dust transport
It is important to note a specific rule from TRGS 727 that the NORRES BAGGERMAN test report highlights: only hoses with an inner diameter between 50 and 160 mm may be used for pneumatic transport of flammable dust. Smaller or larger dimensions are not permitted under this rule, and this must be factored into the hazard assessment when designing a pneumatic transport line.
Download ATEX and TRGS documentation
Frequently asked questions about ATEX and TRGS
What is the difference between antistatic and conductive hose?
An antistatic hose has surface resistance below 109 Ω and covers Zone 22 (dust) and Zone 2 (gas). A conductive hose has below 106 Ω and covers Zone 0/1 (gas) and Zone 20/21 (dust). Conductive provides faster discharge and is required in high-risk zones.
Which hoses can be used in Zone 0?
Zone 0 (continuous explosive atmosphere with gas/vapours) requires a conductive hose (below 106 Ω) properly grounded at both ends. The CP series from NORRES BAGGERMAN — including CP PE 457 EC1, CP VITON 459 EC1 and CP PTFE INOX 475 EC1 — is tested for transport of flammable liquids inside with Zone 0/1/2.
Which hoses can be used for pneumatic transport of flammable dust?
TRGS 727 specifies that only hoses with an inner diameter between 50 and 160 mm may be used for pneumatic transport of flammable dust. The AIRDUC PUR-AS series (350 AS, 351 EC, 355 AS, 356 AS), the NORPLAST PUR C series and BARDUC PUR-INOX are tested for Zone 20, 21 and 22.
What is TRGS 727?
TRGS 727 (Technische Regeln für Gefahrstoffe) is the German technical rule that specifies resistance limits for hoses transporting flammable media. It builds on top of ATEX 2014/34/EU and is the standard NORRES BAGGERMAN's test report references.
Does the hose need grounding for the ATEX approval to work?
Yes. The ATEX approval presupposes that the hose is properly grounded at both ends. If even one end does not have low resistance to ground, the AS property does not work in practice — this is the most frequent error in ATEX installations on hose lines.
What do AS and EC mean in names like AIRDUC PUR 351 EC?
AS typically stands for "antistatic" (surface resistance below 109 Ω). EC stands for "electrically conductive" (surface resistance below 106 Ω). EC versions are intended for higher-risk zones than AS versions.
Are NORRES BAGGERMAN hoses ATEX-certified?
Per ATEX 2014/34/EU, hoses are not themselves "equipment" or "components" and therefore cannot be ATEX-certified. But NORRES BAGGERMAN's test report (DIN EN 10204–2.1) documents that their hoses meet the requirements for electrostatic discharge when properly grounded — that is industry standard for this type of documentation.