Magnum Venus Plastech ATG Gel Coat Gun - Manual (Page 6)

ATG Chopper Gun Manual
Rev. 05/2012 Page | 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 from 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.