什麼是防爆的(機構)設計要求 ?

A. 對於環境的分類主要有以下兩大類:

1. 爆炸性環境(explosive atmosphere)：大氣條件下易燃性物質以氣體、蒸氣、粉塵、纖維或飛絮之型式與空氣形成之混合物，其經引燃後，會自行持續傳播(sustaining propagation)

1-1.爆炸性氣體環境 (Explosive gas atmospheres): 在 1 大氣壓下，易燃性物質以氣體或蒸氣之形式與空氣混合，如引燃時，爆炸會經由擴散至未燃之混合物。

1-2.爆炸性粉塵環境 (Explosive dust atmospheres): 在 1 大氣壓下，易燃性物質以粉塵或飛絮與空氣形成之混合物，其經引燃後，火焰會自行持續傳播。

2. 危險區域(hazardous area, hazardous location)：爆炸性環境出現之區域，或爆炸性環境預期可出現之量，將使得電機設備之建構、安裝及使用上須要特別預防措施之區域。

• 危險區域分為六大類，分別是 Zone 0、Zone 1、Zone 2、Zone 20、Zone 21、Zone 22，每一場域的條件說明如圖所示。

B. 設備保護等級 EPL (Equipment Protection Level) 分為 Ma、Ga、Da、Gb、Db、MB、Gc、Dc。

1.Ga (氣體)，Da (粉塵)，Ma (礦坑)

– Very high protection: the equipment remains safe in normal operation，even in rare fault situations (two faults at once)

2. Gb (氣體)，Db (粉塵)，Mb (礦坑)

– High protection: the equipment remains safe in normal operation, also when faults occur (single fault)。

3. Gc (氣體)，Dc (粉塵)

– Enhanced protection: the equipment remains safe in normal operation，and may have extra protection to minimize ignition risk in fault situations (fault may cause equipment to shut down)。

C. 溫度的等級分為 T1、T2、T3、T4、T5、T6

分級與特定爆炸性氣體環境的高表面引燃溫度有關。在這種爆炸性氣體環境中，使用的設備在溫度分級上不能高過會引燃的溫度。高溫表面有可能引燃爆炸性氣體。

D. 絕緣的機械材料和卓越的電路設計，能確保裝置的防燃性。

1. 金屬外殼（材料組成和材料強度）：

• Electrostatic discharges can initiate combustion or explosions。

• Ga, Da, Ma – very high protection: the equipment remains safe in normal operation，even in rare fault situations (two faults at once)。
• Gb, Db, Mb – high protection; the equipment remains safe in normal operation，also when faults occur (single fault)。
• Gc, Dc – enhanced protection: the equipment remains safe in normal operation, and may have extra protection to minimize ignition risk in fault situations (fault may cause equipment to shut down)。

• 主要的是要符合 UL746C的 f1 認證其，次就是要符合ISO179 or ISO4892-2的測試要求。
• UV light resistance, good weatherability，materials whose properties are not significantly degraded in any of these areas are considered to have passed and are suitable for outdoor use。

• Conductive fillers added which is to impact plastic material's color。(getting dark & black is the trend)。防爆塑料一般來說偏向黑色。

• Related to product spec definition of operation temperature。
• The product supports lower operating temperature, and it should be considered DBTT (Ductile to Brittle Transition Temperature 韌性到脆性轉變溫度) of material properties。
• The material candidate STAT-LOY D3000IEU6 is good for low temperature requirement。

• Surface resistance requirement is defined in spec IEC-60079 as below shown, because electrostatic discharges can initiate combustion or explosions, so the material properties is between static dissipative composites to anti-static composites，the lower surface resistance will impact RF performance, there is a material considered for RF product use, the model name is STAT-LOY D3000IEU6，we need to be carefully if the product with RF function。