Nitrogen (N) PIN FRs cover both inorganic and organic compounds The most widely used N-FRs are melamine compounds (e.g. melamine cyanurate) and amine-derived compounds (e.g. triazines). Some nitrogen-containing PIN FRs are also phosphorus (P) FRs, such as ammonium polyphosphate or melamine polyphosphate.

 
N-FRs can be derived from naturally occurring molecules such as urea or guanidine

Nitrogen based flame retardants are believed to act by several mechanisms:

• Release of inert nitrogen (N₂) so diluting fire gases,
• Cooling by endothermic decomposition,
• Blowing agents in intumescent systems
• Promote polymer degradation, so that the polymer melts away from flame, e.g. melamine cyanamide in polyamide
• Cross-linking, so contributing to char formation
• Improving phosphorus retention in the polymer in fire, so enhancing char barrier effect of phosphorus PIN FRs

Melamine compounds widely used as PIN flame retardants include melamine phosphate, melamine cyanurate, melamine polyphosphate, melamine-poly(zinc phosphate), melamine pyrophosphate, melamine cyanurate. These substances typically are added in the range of 5 – 25 % w/w to polymers, or to intumescent paints or coatings, to reduce fire risk, often in combination with other flame retardants or synergists. Several melamine-based FRs are validated in labels or certifications such as TCO or Ökotex.

Melamine itself is also used as a flame retardant or synergist, e.g., in polymers, intumescent coatings, polyurethane foams.

Other addditive and reactive nitrogen organic PIN FRs include amine-derived compounds (e.g. triazines), isocyanurates, urea, guanidine and cyanuric acid derivatives.