What to Look For

The following examples will help make clear some of the specific issues that can compromise sanitation in food industry equipment.

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.

Under the AMI's Sanitary Design Standards, collection points like this are totally unacceptable. Where buildup occurs there is harmful bacteria.

This modified piece of food equipment provides places for harmful contaminants to hide. The best design is the original design.

Connection Joints

Connections such as this one give many areas for contaminants to build up while keeping out cleaning solutions.

This connection does not provide adequate space for pressurized water to enter, but does provide a place for bacteria to hide and multiply.

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.

Spacers also need to use either smooth welds or connectors such as these.

Overlapping Parts

Tight fittings provide excellent places for containments to hide, while making disinfecting difficult and almost impossible for cleaning crews to perform.

Wide-open mountings allow adequate room for pressurized water to force out any bacteria harboring food particles.

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.

This piece, in contrast, has a minimal-contact overlapping design which does not allow material to enter the equipment body during normal use.

Porous Metal

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.


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.

This design, on the other hand, provides for easy unobstructed draining.

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.

Wash Access Points

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.

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.


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.

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.

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.

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.

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.

The shock absorber shown here is yet another point for contaminants to hide.

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.

The spring and screw head used here are both difficult and likely impossible to clean. A major bacteria harborage point.

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.

Exposed Threads

These types of polished stainless steel nuts, cover bolt threads and provide few places for bacteria to cling.

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.

Overall Design

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 [pdf].

  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.