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Operation and Maintenance
Envistar Flex
DSEF191101.05.EN
Continuous product development may give rise to specification changes without notice.
6.2 Filters (code ELEF)
Filter
The air filters in an air handling unit are designed to prevent dust and other
impurities from entering the building. They should also protect sensitive
components inside the unit, e.g. water coils and heat exchangers, from exposure
to impurities.
The dust separation efficiency varies considerably between various filter types.
The dust collecting efficiency also varies substantially. It is therefore important to
use filters of the same quality and capacity when you change them.
According to guidelines for hygienic design VDI 6022 Part 1: The supply air filter
must be class ePM1-50% (F7) or have a higher filtration efficiency.
The filters are designed for one-time use. If they become fouled, the unit will lose
capacity. The filters should therefore be changed if the pressure drop across
them exceeds the specified final pressure drop. It is important to stop the unit
before changing filters to prevent dust from coming loose and being drawn into
the unit. The inside surfaces of the filter sections should therefore also be clea-
ned when the filters are changed.
