coatings, theyusuallylast for manyyears withminimalmaintenance. The main
thingto rememberis thatfloors mustwithstand use,cleaning, and abuse.
Monolithic coatings are getting betterand better.Thereare some that bondwith
the concrete and haveapproximately the samecoefficientof expansion and
contraction and are seamless.Thereare a number of firmsthat sell these types of
floorcoating. DegussaResinSystems(SRS DegadurCorp.) in particular and
numerousothersin general. Otherflooringmaterials that havebeenused,but are
not recommended in foodprocessing rooms,are vinylor asphalt tile, wood,
metalplates, unless theyare stainless, and bituminous/asphalt.
7.9.2 Drains
Whereverthereare wet processingconditionsdrains willbe required. Floor
drainshaveproven to be sources ofListeriain foodprocessingfacilities unless
correctlydesigned, installed, and maintained, and continually cleanedand
sanitized. Drainagesystems must meetall localand national plumbingcodes.
The foodregulatoryagencies are basingtheirrequirementsof performancerather
thandictatethe constructionof floordrains.The performance theydemand is
completelydrainedfloors:no ponding or standingwateris allowed on the
production floors. The two mostcommondrainsare area drainsor trenchdrains.
Areadrainsmusthavea p-trapand be spacedat a recommended one 4-inch
(0.1 m) drainfor each400 square feet (~40m^2 ) of floor space.The floorshould
be sloped to the drainat a 1±2%slope.Areadrainsare the mostcommonin meat
processing plants and dairies. Thereare areadrainson the market that exhibit
sanitary design and are easilycleaned.All drains shouldbe accessiblefor
cleaning and application of sanitizeron a routinebasis.Areadrainsshould be a
minimumof 4 inches(100mm)in size and equippedwitha removable metal
strainerto catchfoodmaterials,and to preventthe entryof rodents and some
insectpests suchas cockroaches. Theyshould also be designedto minimize the
refluxof contaminatedair that can come whena surgeof waterentersthe drain.
The othermostcommonchoice is trenchdrainsor gutterdrains. Trench drains
shouldbe designedpre-slopedwithrounded or covedbottoms. Squarebottom
drainsare no longer recommendedbecause of the difficultyin cleaning themand
keepingthemclean.Trench drainsshouldbe slopedat 1±2%slope for continuous
drainage. Trenchdrainsshouldbe cleanedroutinelyand the grates constructed to
withstand forklift trafficand any otherwheeledtraffic.There are, on the market,
preformed trenchdrainsthat are easilycleanable and can be quickly installed.
Processingor packagingequipment should neverbe placedoveran openarea or
trenchdrains.The air fromthe drainscontains aerosols that can contain microbes.
Theseaerosols can contaminateotherwise clean equipment.
7.9.3 Walls
Walldesign can be broken into two categories ± externaland internal. External
wallsneedto be water,rodent, and insectproof. The best material for external
wallsis concrete, followedby denseconcrete block. Mediumdensity blockmay
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