Enter the marking from the plate or the certificate. Put an offered replacement in the second field, and the reader checks it against the fitted one: group, temperature, protection level and Ta range. The drawing and the RFQ line update with every change.
On the markings alone: the replacement’s certificate and its conditions decide.
Equipment for an explosive atmosphere carries a marking such as II 2G Ex db eb IIC T4 Gb: the types of protection, the gas or dust group, the temperature class and the protection level. Enter it as it stands on the plate, and the reader takes it apart, shows the zones and temperature classes it suits and writes the RFQ line.
The marking narrows a replacement; the certificate decides it. Where the certificate number ends in X, its specific conditions of use apply as well.
Letters after Ex: d flameproof enclosure, e increased safety, i intrinsic safety, p pressurised enclosure, m encapsulation, o liquid immersion, q powder filling, n type n, t protection by enclosure for dust. A trailing a, b or c is the level: ia, db, ec.
IIA, IIB and IIC are gas groups, IIC the most demanding (hydrogen, acetylene); IIC equipment also meets IIB and IIA. IIIA, IIIB and IIIC are dust groups: combustible flyings, non-conductive and conductive dust. Group I is mining.
T1 to T6 cap the hottest surface, from 450 °C down to 85 °C; dust equipment marks the temperature itself, as T85 °C. The level Ga, Gb or Gc suits zone 0, 1 or 2; Da, Db and Dc zones 20, 21 and 22.
| Class | Surface, at most | Also meets |
|---|---|---|
| T1 | 450 °C | — |
| T2 | 300 °C | T1 |
| T3 | 200 °C | T1, T2 |
| T4 | 135 °C | T1, T2, T3 |
| T5 | 100 °C | T1, T2, T3, T4 |
| T6 | 85 °C | T1, T2, T3, T4, T5 |
A zone also takes equipment of a stricter level: zone 1 takes Gb or Ga, zone 2 Gc, Gb or Ga. In the ATEX form, II 2G is equipment group II, category 2, gas; categories 1, 2 and 3 match zones 0, 1 and 2.
Types of protection and levels: Heating & Process ("Explosion protected equipment marking"), the R. STAHL marking guide and Wikipedia ("Electrical equipment in hazardous areas"); levels, zones and ATEX categories: BARTEC Academy and Wikipedia; groups and temperature classes: Wikipedia and Heating & Process; square brackets: HSA Ireland and Heating & Process; X and U: IECEx decision sheets, Heating & Process and Cortem Group; the normal ambient range: IEC 60079-0 as summarised by its publishers, and FM Approvals.
Flameproof enclosure and increased safety, both at level b; gas group IIC, which also covers IIB and IIA; temperature class T4, the hottest surface at most 135 °C; and protection level Gb, for zone 1 and zone 2.
The certificate lists specific conditions of use that the installation has to meet. A U instead marks an Ex component, which is not complete equipment and goes into certified equipment; the two letters are not used together.
On temperature, yes: a T6 surface stays at or below 85 °C, inside the 135 °C of T4. The group, the protection level and the certificate still have to suit the place where it is fitted.
The whole Ex marking, the certificate number, the ambient range if one is marked, the maker and type from the plate, a photograph of the plate and the quantity; where the number ends in X, ask for the certificate with the offer.
Reading the marking is a cross-check, not a selection. Attach a photograph of the plate and the certificate number, and Vessel Core checks them before an offer goes back.
