sensors & systems - Industrial Technology Magazine

CONTROL TECHNOLOGY // EXPLOSION PROTECTION
// MEDICAL TECHNOLOGY
Introducing: the safety
sensor for gourmets
DESIGN REPORT
Hygienic
conveying
Choosing the right chain conveyor system
for hygienic applications can make a big
difference to both initial expenditure and
running costs. Ian Dickson of Bosch
Rexroth provides some useful pointers
If you have a desire for good food, you would certainly lay
special attention on hygiene at the processing of food.
We have developed our magnetic safety sensor RC Si M30
stainless steel IP 69K especially for this complex application.
The enclosures of the sensor and actuator are fully
made of stainless steel and even the jet of a high-pressure
washer (protection IP 69K) does not have any effect
on the reliability of the magnetic safety sensor. So this is
why this is the ideal switchgear for gourmets – and for
the manufacturer of food processing machines. Further
information:
steute UK & Ireland, Maylite Business Centre, Martley,
Worcestershire, WR6 6PQ, Phone 0 18 86 / 88 77 22, Fax
0 18 86 / 88 77 25, infouk@steute.com or www.steute.co.uk
When approaching the
choice of chain
conveyor systems for
applications in the
food, pharmaceutical and similar
sectors, perhaps the first question to
ask is just how hygienic the
installation needs to be. In most
cases, this equates to another
question: will the installation be
subjected to washdown? If the
answer is no, then it’s likely that a lot
of money can be saved by choosing
an appropriate aluminium-frame
conveyor system.
A well-designed system of this
type will have a minimum of cavities
and crevices that might harbour
contaminants, and a conveyor chain
manufactured from high-grade plastic
that does not fret or shred. The
surface of the chain will also be as
closed as possible to minimise the
risk of harbouring dust and dirt. An
installation based on conveyors of
this type is, for example, eminently
suited to the handling of packaged
products.
For those applications where
washdown is essential, conveyors
with frames made from stainless steel
are the usual choice. This material is
not only inherently hygienic, but is
also able to withstand attack by the
often aggressive chemicals used in
washdown cleaning. Stainless steel
conveyors share many of the features
of the aluminium-frame types already
discussed but are constructed from
structural members with an open
section. This allows them to be
thoroughly cleaned by pressure
washing.
Ancillary equipment
It’s not just the conveyors themselves
that need to be considered in hygienic
applications, as mechanical handling
systems almost invariably include a
wide range of ancillary equipment.
Typically this might include gates,
diverters and stops, all of which are
usually pneumatically actuated. In
these situations, thought must be
given to the pneumatic valves and
cylinders used.
In installations where washdown
is used, are the cylinders made from
stainless steel? Is the grease used to
lubricate the cylinders edible? And,
particularly where washdown is being
used, is it necessary to put the
pneumatic valves into an enclosure
for protection? This last point is more
important than it may at first appear.
If the valves need to be protected,
the only cost-effective way to do this
traditionally is to group several valves
SAFE SWITCHGEAR FOR COMPLEX
AND CRITICAL APPLICATIONS
20 More details: Write in 200 on the free information card
INDUSTRIAL TECHNOLOGY • May 2008