SPILL RESPONSE CONSIDERATIONS FOR

METHYLENE DIPHENYL ISOCYANATE (MDI)

(this procedure also applies to TDI)

CAS RN 101688

Pure form: crystals or fused yellow solid. Frequently dissolved in solvents such as acetone, benzene, kerosine, or nitromethane.

EXPOSURE GUIDE LINES

ACGIH

TLV 0.005 ppm 0.051 mg/m³

OSHA

STEL 0.02 C ppm 0.2 C mg/m³

NIOSH

REL 0.005 ppm 0.05 mg/m³

STEL 0.02 C ppm 0.2 C mg/m³ (10 minute exposure)

Extremely toxic, strong irritant. Capable of producing severe dermatitis and bronchial spasms. Potent sensitizer.

Note: most industrial applications involve a polymeric form of MDI or TDI which has a reduced vapor pressure and it much less hazardous.

Minimum PPE:

Minimum PPE for MDI or TDI response includes:

FULL NEOPRENE BOOTS WITH OVERBOOTS

KAPPLER CPF 2 (or higher) SUITS, with hoods up

NEOPRENE GLOVES with SOLVEX^(TM) GLOVES AND N-DEX^(TM)UNDERLINERS

SCBA

HARD HAT WITH FACE SHIELD

Spill Clean-up procedures:

Rapid vapor control is essential. Activated carbon is recommended. MagicSorb^(tm) is a second choice, but will not fully control MDI or solvent vapor.

Place the sorbent material in a sealable plastic pail and remove to outdoor location. Overpack pail in drum.

Monitor hot zone for MDI and solvent. If either are detectable, reapply activated carbon and supply increased area ventilation. MDI is not water soluble.

ADVANCED CHEMICAL SAFETY (ACSafety) does not normally recommend the use of solvents for area decontamination. If MDI contamination can not be reduced below detectable levels with activated carbon adsorption, removal of contaminated materials is strongly suggested.

MDI is incompatible with strong oxidizers, water, acids, bases, and amines. It may foam, spatter, or release toxic gases including HNCO, HCN and NO_x.

Fire fighting: Use Dry chemical or CO₂. SCBA is mandatory for any fire response.

Spill residue disposal: All MDI contaminated residue should be incinerated.