Magnum Venus Plastech PATRIOT SS PAT-CCP-LS-0590-SS - Manual (Page 6)

MAGNUM VENUS PLASTECH Patriot SS Chop Check Manual 6
2.2 Catalyst (Methyl Ethyl Ketone Peroxide)
MEKP is among the more hazardous materials found in commercial channels. The safe handling
of the “unstable (reactive)” chemicals presents a definite challenge to the plastics industry. The
highly reactive property which makes MEKP valuable to the plastics industry in producing the
curing reaction of polyester resins also produces the hazards which require great care and
caution in its storage, transportation, handling, processing and disposal. MEKP is a single
chemical. Various polymeric forms may exist which are more or less hazardous with respect to
each other. These differences may arise not only from different molecular structures (all are,
nevertheless, called “MEKP”) and from possible trace impurities left from the manufacture of the
chemicals, but may also arise by contamination of MEKP with other materials in its storage or
use. Even a small amount of contamination with acetone, for instance, may produce an extremely
shock-sensitive and explosive compound.
Contamination with promoters or materials containing promoters, such as laminate
sandings, or with any readily oxidizing material, such as brass or iron, will cause
exothermic “redox” reactions which can become explosive in nature. Heat applied to
MEKP, or heat build-up from contamination reactions can cause it to reach what is called
its Self-Accelerating Decomposition Temperature (SADT).
Researchers have reported measuring pressure rates-of-rise well in excess of 100,000 psi per
second when certain MEKP’s reach their SADT. (For comparison, the highest pressure rate-of-
rise listed in NFPA Bulletin NO.68, “Explosion Venting”, is 12,000 psi per second for an explosion
of 12% acetylene and air. The maximum value listed for a hydrogen explosion is 10,000 psi per
second. Some forms of MEKP, if allowed to reach their SADT, will burst even an open topped
container. This suggests that it is not possible to design a relief valve to vent this order of
magnitude of pressure rate-of-rise. The user should be aware that any closed container, be it a
pressure vessel, surge chamber, or pressure accumulator, could explode under certain
conditions. There is no engineering substitute for care by the user in handling organic peroxide
catalysts. If, at any time, the pressure relieve valve on top of the catalyst tank should vent, the
area should be evacuated at once and the fire department called. The venting could be the first
indication of a heat, and therefore, pressure build-up that could eventually lead to an explosion.
Moreover, if a catalyst tank is sufficiently full when the pressure relief valve vents, some catalyst
may spray out, which could cause eye injury. For this reason, and many others, anyone whose
job puts them in an area where this vented spray might go, should always wear full eye protection
even when laminating operations are not taking place.
Safety in handling MEKP depends to a great extent on employee education, proper safety
instructions and safe use of the chemicals and equipment. Workers should be thoroughly
informed of the hazards that may result form improper handling of MEKP, especially in regards to
contamination, heat, friction and impact. They should be thoroughly instructed regarding the
proper action to be taken in the storage, use and disposal of MEKP and other hazardous
materials used in the laminating operation. In addition, users should make every effort to:
A. Store MEKP in a cool, dry place in original containers away from direct sunlight and away from
other chemicals.
B. Keep MEKP away from heat, sparks and open flames.
C. Prevent contamination of MEKP with other materials, including polyester over spray and
sandings, polymerization accelerators and promoters, brass, aluminum and non-stainless steels.
D. Never add MEKP to anything that is hot, since explosive decomposition may result.