The bt4 rating on explosion-proof equipment indicates two primary parameters. Additionally, the ‘b’ in bt4 denotes Class IIb, signifying its use in non-mining settings.
| Gāzes klasifikācija | Temperatūras grupa | |||||
|---|---|---|---|---|---|---|
| - | T1 | T2 | T3 | T4 | T5 | T6 |
| - | T＞450 | 450 ≥ T > 300 | 300 ≥ T > 200 | 200≥T＞135 | 135 ≥ T > 100 | 100 ≥ T > 85 |
| I | Metāns | |||||
| IIA | Etāns, propāns, acetons, fenetils, enē, aminobenzols, toluols, benzols, amonjaks, oglekļa monoksīds, etilacetāts, etiķskābe | Butāns, etanols, propilēns, butanols, etiķskābe, butilesteris, amilacetāts, etiķskābes anhidrīds | Pentāns, heksāns, heptāns, dekāns, oktāns, benzīns, sērūdeņradis, cikloheksāns, benzīns, petroleja, dīzeļdegviela, nafta | Ēters, acetaldehīds, trimetilamīns | Etilnitrīts | |
| IIB | Propilēns, acetilēns, ciklopropāns, koksa krāsns gāze | Epoksīda Z-alkāns, epoksīda propāns, butadiēns, etilēns | Dimetilēteris, izoprēns, sērūdeņradis | Dietilēteris, dibutilēteris | ||
| IIC | Ūdens gāze, ūdeņradis | Acetilēns | Oglekļa disulfīds | Etilnitrāts | ||
B
The ‘B’ indicates the gas level in the environment, determined through experimental reference levels. This classification primarily accounts for the maximum gaps through which gases can pass and their minimum ignition currents. It is categorized into three levels: Class A, B, and C. Class A environments are relatively safe, Class B are more hazardous, and Class C are dangerous, though less common. Class C explosion-proof equipment is applicable in both Class A and B environments, Class B equipment is suited for Class A settings, and Class A equipment is exclusively for Class A environments. As a result, Class B is generally the standard level for explosion-proof equipment in the market. The hierarchy among these classes is Class C > Class B > Class A.
T4
T4 denotes the temperature classification within the environment, based on the gases’ relative ignition points. Higher temperature classifications necessitate lower operating temperatures and more stringent equipment specifications. These classifications are tailored to specific production standards, requiring the selection of explosion-proof equipment to match the actual environmental temperature levels. T4-rated equipment is designed to operate at temperatures ranging from 135 to 200°C.
The bt4 explosion-proof rating is the most prevalent, providing extensive usability and a broad selection of applicable environments.
