Detergents
The effectiveness of detergents is relatedto theirchemical activity, composition,
concentration,surface tensionpropertiesand dispersing power.The detergent
mustdissolve rapidly and completelyin water,and mustact quicklyon the soil
or deposits it is expectedto remove(suchas protein, fat, beerscale,hop resins,
burntyeast,trub,pulp).
The detergentshouldalso havea highsoil-carrying capacityand be easyto
flushoff with water.In addition,the detergent shouldnot foam,and shouldbe
compatible withthe othermaterials usedin the plant. Cleaning detergentsmust
havea conductivitywellabovethat of water,and demonstratea linear relation
between concentrationand conductivity.Moderncleaning detergents can reduce
the cleaning parameterR throughimproving one or more of thesefactors.
Cleaningtime
Cleaning timerelates to the totaldurationof the cleaningprocess,and must be
sufficient to allowfor the dissolutionof soil,swelling of soil,saponification,
dispersion and finalrinsing. The last residual layerof the depositon a surface
can onlybe attackedby a detergent if it is allowed longenoughto react, withthe
reactiontimebeing the timethe detergent is in contactwiththe deposit at the
rightconcentrationand the right temperature.
The duration of cleaningis determined by the timeit takesto completethe
differentphasesof the cleaningoperation. These phases are the pre-rinse,where
all loosecomponents are flushedout, the mainwash, which must be checkedat
critical points (e.g.heatexchangerplates, pipebends, tank,internals),the
intermediate rinse, where the solution being flushed out is checked for
neutrality, and the final rinse, where the solution being flushedout is checked to
Fig. 27.2 Fourcleaningparameters.Improving cleaning-in-place (CIP) 427