15.2.3 ZoneH
ZoneH (whereH standsfor the Highhygiene zoneclassification) applies to an
areawhere the highest levelof hygienedesign requirementsis essential.The
areamust be completely contained. Thiszoneclassificationis typicalfor open
processing, where the highesthygienic designcriteriaappliesto the equipment
involved. The objectivefor this zoneclassificationis to controlall product
contaminationhazards and to protect the interiorof foodprocessingequipment
fromexposure to atmosphere. Filteredair mustbe supplied to this area.
ZoneH relatesto areas of the plantlayout,typically foodproductionareas
where:
∑ there is continuous exposure to atmosphere of products sensitive to
contaminationor exposure of foodcontactsurfaces to atmosphere;
∑ evenshortexposure to atmosphere of products sensitiveto contamination can
resultin safetyor qualityhazards.
ZoneH areasshould be limitedin size and contain as simplean equipment
layoutas possible,allowing enoughroomfor operation,cleaningand main-
tenance.Therefore, where possible, equipment such as fans,pumps, power
supply and ventilation systems should be placed outside the area. Such
equipment willthen havea lower hygienicstatus, and a lower degree of
cleaning. Protectiveclothing,headgear (hairnets), changeof shoesfor operators
and shoecoversfor visitorsshould be worn,and put on prior to entering the area.
15.2.4 Wetor dry processing and typeof cleaning
The differentzonescan be furtherclassified accordingto wet and dry processing
areas.In somecases a zonecategory can also be classified differentlyif special
products are involved requiringevenhigherhygienic standards, e.g. babyfood
processing. However, it is necessaryto consider whatdefinesthe boundary
between the zones. Zonesmaytemporarily be classifieddifferently,e.g. for
maintenance or cleaning purposes.Release procedures are adopted whenthe
zonereverts to its original classification.
The typeof cleaning permittedin a given zoneis an essentialpreventive
factorto any area.Threecategories shouldbe considered:
∑ Dry cleaning(d). Thisapplies to areaswhere no cleaningliquidsare used,
and cleaning is onlyby vacuumcleaners,dustingcloths,brooms and brushes.
Pressurised air shouldneverbe usedas a means of blowing downsurfaces.
∑ Controlled wet cleaning (cw).Thisappliesto areasthat are definedas dry
duringprocessing, althoughsomewet cleaningis permitted.Theseareas are
normally cleaneddry,but occasionally are fully or partiallywet cleaned,
whenlimited amounts of water are used. Drying of all surfaces after
controlled wet cleaning is essential.
∑ Wetcleaning (w).Thisappliesto areas wherethe entireroomor zoneis
alwayscleanedwet. The contents (equipment, cabletrays,ceilings,walls, etc.)
are wet washedwithoutrestrictionson the amount of cleaningliquidused.
Improvingthe hygienicdesignof electricalequipment 241