Keep Product Clean In and Out of the Cleanroom
--Part 2: The Program
By Barbara Kanegsberg, Ed Kanegsberg,KevinaO’Donoghue
Thefirststepindeveloping an effective precision cleaning processfortheproductis to determine where cleaning can be avoided.Keepingtheproductclean, particularly during transfer and storage,isanimportantpart of your contamination control program.
Much effortisexpendedinkeeping the cleanroom clean, in monitoringthecleanroom. Mucheffortis expended in developing, validating,andmonitoringcleaningprocesses for both so-called "high-end"productsand forindustrialapplications. It is critical to managethreemajorsources ofcontamination for products fabricatedwithinthecleanroom. Thesecontamination sources are:
·People
·Equipment
·Transfer
EFFECTIVE TRANSFER
Many itemssuchasrawmaterials for use in the manufacturing of theproductaresupplieddouble bagged or triple bagged dependingonthemanufacturingprocess. The outer packaging couldpotentiallybehighlycontaminated so careful removal of thispackaging isofutmostimportance.
Sometimespallettrucksofcardboard boxes are loaded into the transfer area.How doyouremovecontamination from those parts when going fromthedirtyside to theclean side? How do you avoid particlegeneration?Ingeneral, it iswise to remove all cardboard packagingoutsideofthe controlledenvironment. As we explained inthepreviouscolumn,1 the materialtransfer room is acontrolledenvironmentthat includes a 'dirty'side and a 'cleanside.'However,contamination must be minimizedeven in the'dirtyside.'Therefore, remove the cardboard in an areaoutside ofbutproximalto the transfer area; then immediately movematerialstothetransfer area.
CLEANING
Set a cleaning protocol for surfaces, packaging,andproductduringtransfer. We have observed people sprayingisopropylalcohol(IPA)on a part, then transferring it intothecleanroom.Simplyanointing the material with IPA may notbeadequate. Rememberthateffective cleaning typically involvesbothphysical andchemicalaction. A more effective, but stillconvenientcleaningprotocol isto use an alcohol spray, such as IPA,inconjunctionwithnon-linting wipes. The IPA must be of highqualityand freeofresidue. Large storage containers and benchtopdispensersmustbemade of materials that do not leach residue. Whilethereisnoperfect cleanroom wipe, the selected wipe must beoptimalfortheapplication.2
In the transfer room or area, first clean the benchtopandracking.Assoon as material is transferred to the dirty sideofthetransferroom,1 clean the outer bag. Veryoftenthisouter bag isremoved and not cleaned down. The riskofthistechnique is thatcontamination from this outer bag cangetontothe inside bag and ontothe gloves of the materialhandlerwhowipes the inside bag.
STORAGE
Once cleaned, the outer bag can be removed. The insidebagshouldthenbe wiped down and left on the pre-cleaned benchtoporrackingfixturefor cleanroom personnel to collect. If thematerialis lefton thisracking for a long period of time, thencleanroompersonnelshouldwipe it again as a precautionary measure,beforebringing itinto thecleanroom environment. The definition of"along time,"analogous to aClean Hold Time inpharmaceuticalvalidation, isspecific to thefabrication process andfacility; youshoulddetermine and document areasonablepolicy.
Sometimes material is stored within the materialtransferareaorcleanroom environment itself until ready for use. Inthiscase,thebenchtop/racking surface and outer bag is wipeddownthoroughlyasdescribed above and left on the surface for entryintothestoragearea. All materials stored for long periods oftimewithinthematerial transfer or cleanroom should be leftdoublebagged.Itshould be noted that if materials are stored withinacleanroomintotes or on racking, then these should be cleanedonaregularbasis as part of the cleanroom cleaning schedule.Whenthematerialis required for use, then the outer bag shouldbecleanedagain andremoved and the inner bag cleaned beforeopening.Finalpackagingshould be removed only just prior to useofthematerial.
CONTAMINANTS DEAD AND ALIVE
It is important to understand the sourceofparticulatecontamination,both viable and non-viable. Ifsterilityis the onlyconcern, thensterile materials, double ortriplebagged, may notneed to go throughsuch rigorous cleaning ofthepackaging as eachlayer of packaging issterile. However,careshould be taken whenremoving the outerpackaging to ensure itdoesnot pose a threat tothe inner packaging.Be aware thatparticlecounts include bothviable and non-viableparticles.
LARGE ITEMS
Transferring bulky materials isparticularlydifficult.Sometimes,only parts of the assembly can becleaned priortotransfer. Inmedical and pharmaceutical applications,cleanlinessoflarge,bulky objects is typically determined byswabbing andtestingformicrobial contamination. Aside from the timefactorinmicrobialanalysis (perhaps three to five days), theabsenceofsignificantmicrobial contamination does not necessarilyruleoutnon-viablecontamination, particulate, and thinfilm.Samplingfollowed byparticulate counting and/or non-volatileresiduetestingmay berequired.
Some items may have to be wheeled into the cleanroomontrolleysdueto the weight or size of the material. Thesetrolleysshouldbethoroughly cleaned before entering the cleanroom,inparticularthewheels. Sticky mats may help to removeexcesscontaminationfromthe floor area but this alone is not a goodenoughclean forentryinto the cleanroom; the hubs and axles canalsobecontaminated. Tominimize entry of contamination tothecleanroom,one trolley canbe used to transfer the material fromthewarehouseto the 'dirty'side of the material transfer roomandanothertrolley that isdedicated for cleanroom use can be usedtotransferthe materialinto cleanroom from the 'clean' side.Thismethodhowever doesinvolve an extra handling step.Unfortunately,moreoften than not,this extra desirable transfer stepis judged tobeconsumption ofvaluable time. Setting up writtenjustifiedpoliciesfor suchactivities may be helpful.
ACCOUNTABILITY
With larger assemblies there is also the issueofresponsibilityandaccountability. The people in the warehousemaymove materialsintothe transfer area without cleaning them, ontheassumptionthatcleanroom technicians will take care ofcleaningissues. Thoseinthe cleanroom may assume that the parts havebeenpre-cleaned.Evenworse, in the interest of supposedefficiency,managementmaytacitly support or even mandate an unwisepolicyofbringingmaterials into the cleanroom without cleaning them.Ifyouarefaced with such fallacious cost-cutting measures, andiflogicdoesnot prevail, tracking the failure rate may bethemostcompellingapproach.
IS AUTOMATION THE ANSWER?
Not always. The assumption is made that people aretheproblemandthat if you remove the people, there willbenocontaminationproblems associated withmaterialstransfer.Automation simply doesthings the same way eachtime; youmay beautomating a process thatinherentlygeneratesparticles.
The equipment itself can generate particles. Wehaveobservedtransferequipment, moving materials into a cleanroom,thathadbothparticulate and nonparticulate contamination onthe"tracks."Thedesign and maintenance of transfer andprocessequipment mustbeconsidered, because equipment and fixturingcandegrade.Sometimes,the same racks or trays are used in bothearlystages ofproductionand in the cleanroom. It is importanttoseparate andsegregate theprocesses (Figure 1). People need tobeinvolved indesign, oversight,and monitoring oftransferprocesses.
KEY PROGRAM
The material transfer process should be a key elementinthecleanroomcontamination control program. Too often, theprocessofmaterialstransfer is not given a huge amount of time, ifany,inemployeestraining programs. It is vital thatpersonnelperformingthe materialtransfer process understandtheresponsibility andimportance of theirrole and are fully awareofthe impacts oftheir methods andpractices. They mustalsounderstand the impactof their behaviors,particularly thenegativeimpact of incorrectbehaviours. Personnelawarenessandunderstanding is crucial forthis process tobeperformedeffectively; for this to happen, theremust bemanagementsupportand understanding.
References:
1.B. Kanegsberg, E. Kanegsberg, and K.O'Donoghue,"KeepingProductClean In and Out of the Cleanroom, Part1:TheInterface,"Controlled Environments Magazine, Feb. 2009.
2.Siegerman, H., "Wiping SurfacesClean,"ViconPublishing,2004.
Our colleague, Dr. Kevina O'Donoghue, isaMicrobiologistatSpecialized Sterile Environments, Galway,Ireland.She canbereached at kevina@cleanrooms.ie
Barbara Kanegsberg and Ed Kanegsberg, "the Cleaning LadyandtheRocketScientist," are independent consultants incriticalandprecisioncleaning, surface preparation, andcontaminationcontrol.They arethe editors of The Handbook forCritical Cleaning,CRCPress.Contact them at BFK Solutions LLC.
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