Isocyanate Hazard
311075R 9
Isocyanate Hazard
Foam Self-ignition
Moisture Sensitivity of
Isocyanates
Isocyanates (ISO) are catalysts used in two
component foam and polyurea coatings. ISO
will react with moisture (such as humidity) to
form small, hard, abrasive crystals, which
become suspended in the fluid. Eventually a
film will form on the surface and the ISO will
begin to gel, increasing in viscosity. If used,
this partially cured ISO will reduce perfor-
mance and the life of all wetted parts.
To prevent exposing ISO to moisture:
• Always use a sealed container with a desic-
cant dryer in the vent, or a nitrogen atmo-
sphere. Never store ISO in an open
container.
• Keep the felt washers in the pump wet-cups
saturated with Graco ISO pump oil, Part
No. 217374. The lubricant creates a barrier
between the ISO and the atmosphere.
• Use moisture-proof hoses specifically
designed for ISO, such as those supplied
with your system (see page 63).
• Never use reclaimed solvents, which may
contain moisture. Always keep solvent con-
tainers closed when not in use.
• Never use solvent on one side if it has been
contaminated from the other side.
• Always park pumps when you shutdown,
see page 27.
• Always lubricate threaded parts with Part
No. 217374 ISO pump oil or grease when
reassembling.
Spraying materials containing isocyanates
creates potentially harmful mists, vapors,
and atomized particulates.
Read material manufacturer’s warnings and
material MSDS to know specific hazards and
precautions related to isocyanates.
Prevent inhalation of isocyanate mists,
vapors, and atomized particulates by provid-
ing sufficient ventilation in the work area. If
sufficient ventilation is not available, a sup-
plied-air respirator is required for everyone in
the work area.
To prevent contact with isocyanates, appro-
priate personal protective equipment, includ-
ing chemically impermeable gloves, boots,
aprons, and goggles, is also required for
everyone in the work area.
Some materials may become self-igniting if
applied too thickly. Read material manufac-
turer’s warnings and material MSDS.
The amount of film formation and rate of
crystallization varies depending on the
blend of ISO, the humidity, and the tem-
perature.
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