A variety of industries are grouped
together so that prevention of contamination by gear or transmission lubricants
can be stressed. While such possibility is remote, Government Inspectors are
becoming more particular in this regard. Also, both manufacturers
of food processing machinery and operators of plants are aware
of the importance of
cleanliness and lack of contamination. Proper seals, well
maintained, should prevent leakage from gear cases. As an aid in this direction,
over lubrication should be avoided and when and if lubricating grease is
applied, this should be at very low pressure. As a general rule, straight
petroleum oils can be used in gear lubrication of the subjected equipment. Some
operators of machinery handling foodstuffs prefer light colored lubricants. White
oils are available in viscosities up to 300 or perhaps 500 SUS at 100 degree F.
The same
oils can be thickened
to a semi fluid or non flowing
nature by the use of fine silica or non toxic
soaps, such as aluminum
or calcium. Light colored fillers, such
as magnesium oxide
or zinc oxide, can be added to
lubricating greases, although fillers have little if any
place in gear lubrication.
Caution should
be used in supplying
gear lubricants containing
additives to food
processing plants. Oils containing
EP agents should only be
used if the gear cases
containing such oils are sufficiently
removed from the food
products so that leakage will
cause no contamination. Foam inhibitors
are permissible because the concentration is quite low. Stable oils are recommended
because they will require a minimum of oxidation inhibitors. Such additives, as
well as rust inhibitors, which will
be desirable under wet
conditions, should only be
used with assurance that
the compounds are not harmful
to animals or humans.
Simplification of gear
lubrication should be
kept in mind and if
possible, only one type and grade
of gear oil be used in a specific
plant. Thus, in spite of the
recommendations above for the use
of such oils with very
judicious inclusion of
additives, the suggestion has
been made^31 that a
premium grade rust
and oxidation inhibited turbine
and hydraulic oil
be used in all gear reducers
in dairies. Therefore, similar oils will also be recommended for other
foodstuff handling equipment. Open gearing will be found in some food handling machinery
or plants. It is
presumed that such gears will be so located
that drips from the
same will not
contaminate food. Therefore, a
general recommendation is to
apply a residual
type of gear
lubricant very sparingly. The viscosity will be dictated by the
service but will probably be one of 1000 to 2000 SUS at 210 degree F.
In the group
to follow, equipment used
to process some medicinal items,
alcohol products etc., will be included since they
are restricted to the
same limitations as far as
contamination is concerned. By mentioning
some of the unit operations
which may be encountered in food
processing, the variety of machinery
involved and therefore, the possibility of the use of gear
drives will be evident. Thus, cleaning, coating, conveying, decorating, disintegrating, drying, evaporating, forming,
heating, mixing, packaging, pumping and
separating are a few such operations.
