Which Level of Explosion-Proof Is Higher, IA or D

The flameproof designation “d” aligns with the EPL Gb category, which is appropriate only for gas environments in Zones 1 and 2;

Explosion proof type	Gas explosion-proof symbol
Intrinsic safety type	ia,ib,ic
Flame type	d,db

The intrinsic safety designation “ia” is associated with the highest level, EPL Ga, covering gas environments in Zones 0, 1, and 2;

Hence, the intrinsic safety type ia offers a superior level of explosion protection compared to the flameproof type.