design principles
what to look for
liabilities
contaminants
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WHAT TO LOOK FOR
The examples given on this page are provided to show what constitutes
good and bad sanitary design. Regardless of what type of equipment
will be used in your facility, the design standards will still apply.
What to Look For:
Bacteria Buildup Joints Overlapping Parts Porous Metal Drainage
Access Points Crevices Exposed Threads Overall Design
| Click on Picture to Enlarge |
 Bacteria Buildup
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A scratch on a piece
of stainless steel acts as a harborage point for Listeria. ~ 1.2 units/millimeter
or 47 units/inch. An incorrectly designed piece of equipment can harbor
much more bacteria. |
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Under the AMI's Sanitary Design Standards, collection points like this are totally unacceptable. Where buildup occurs there is harmful bacteria.
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This modified piece of food equipment provides places for harmful contaminants to hide. The best design is the original design.
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Connection Joints
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Connections such
as this one give many areas for contaminants to build up while keeping
out cleaning solutions.
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This connection does not provide adequate space for pressurized water to enter, but does provide a place for bacteria to hide and multiply.
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The polished round
spacers used with this connection joint keep food particles and bacteria
from hiding and give plenty of places for water to wash out contaminants.
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Another picture of the spacers from below.
Acceptable connections need to be done using either smooth welds or use spacer connectors such as these.
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| Click on Picture to Enlarge |
Overlapping Parts
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Tight fittings provide excellent places for containments to hide, while making disinfecting difficult and almost impossible for cleaning crews to perform.
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Wide-open mountings allow adequate room for pressurized water to force out any bacteria harboring food particles.
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This particular design
provides a removable tray for cleaning. The removable tray does not
provide sufficient overlap to prevent food particles from entering
the body of the piece of equipment.
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This piece, in contrast,
has a minimal-contact overlapping design which does not allow material
to enter the equipment body during normal use.
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| Click on Picture to Enlarge |
Porous Metal
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Porous materials
such as the use of aluminum used in this part almost guarantee the
growth bacteria. Stainless Steel polished to a high level or the use
of anodized or similar processed aluminum are acceptable.
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| Click on Picture to Enlarge |
Drainage
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The drainage hole
on the bottom of this piece of equipment gives a place for water and
contaminants to drain, however the placement of a connecting piece
with no spacers next to the drainage hole will ensure the buildup
of bacteria.
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This design, on the
other hand, provides for easy unobstructed draining.
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This is another example
of potential drainage problems. Although the drainage hole has been
provided in the design, there are many obstructions where contaminants
can be trapped.
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| Click on Picture to Enlarge |
Wash Access Points
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The corners
on this piece of equipment, that would normally be covered with an
overlapping pan, are almost completely closed; giving just enough
area for particles to be stuck and bacteria to hide, but not enough
for cleaning solutions to enter and drain.
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This design,
also with corners that would normally be covered
during normal operation, provide excellent wide openings where
cleaning fluids can enter and contaminants can drain.
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| Click on Picture to Enlarge |
Crevices
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The closed-box construction of the back of this piece of equipment,
which is not hermetically sealed provides many small
places for contaminants to enter but not enough area for cleaning
fluids to enter and drainage to occur.
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A close up of the same piece of equipment reveals another problem.
A large gap occurs where two pieces of spot-welded metal come together.
Under the sanitary design standards set forth by the AMI, this type
of seem either needs to be eliminated or done using a smooth weld.
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This particular design uses an open-back construction for a supporting piece. Since hermetically sealing a box is difficult and expensive, this type of design is preferred for its cleanability.
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The control
panel on this piece of equipment has a crevice around the controller.
This type of design is especially dangerous since the bacteria-harboring
design is also a main point of contact for the user who is likely
to touch (and contaminate) food after using this panel.
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The corner construction on this piece of equipment is particularly bad. A supporting piece of welded bar steel provides a point for food material to hide and bacteria to grow.
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The shock
absorber shown here is yet another point for contaminants to hide.
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The shock absorber shown cannot be easily removed and replaced without tools.
It also is not adequately sealed and is not made of non-porous neoprene,
a bacteria resistance bushing material.
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The spring
and screw head used here are both difficult and likely impossible
to clean. A major bacteria harborage point.
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The spiral-type cord connector is yet another place for food
particles to collect and bacteria to hide. All surfaces should
be smooth when possible.
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Exposed Threads
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These types of polished stainless steel nuts, cover bolt threads and provide few places for bacteria to cling.
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The nuts used here minimize thread exposure, while the nut's plastic top and bottom also ensure that bacteria will not collect on the unexposed parts of the threads.
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Overall Design
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One key feature should stand out on any piece of food processing Equipment. That is being able to "CLEAN IN PLACE" (CIP).
The design should be simple inside and out. Below is a condensed list of what to look for. For a more complete list, consult the American Meat Institute's Ten Principles of Sanitary Design
1. Closed-box construction should never be done without the use of hermetically sealing the box.
2. Places where any type of particle can get into should also have a wide enough access point for cleaning fluids to enter and adequate drainage should also be provided.
3. Crevices, overlapping parts, bolt threads, and other contamination collection points should be eliminated through simple uncluttered design.
4. Porous metals should never be used.
5. Parts need to be connected in one of two ways: smooth welds, or spacers and bolts with unexposed threads.
6. Disassembly should be easy and not require the use of tools
in instances where machine parts need to be taken apart for cleaning.
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Examples of Good Sanitary Design
QuickSilver Sanitary Design Bench Scale
Chicago Stainless, Makers of sanitary design pressure gauges
Aegis Lift Deck Floor Scale
Wyssmont Food Dryer
Tapflo Sanitary Design Pumps
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