MVP TALON Gun, Manual

Page: 8 / 78

Talon Internal Mix Gun Manual
Rev. 01/2015 Page | 8
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.