
system
air
35
Caution
Keep the inner and outer surface of the inspection glass clean. If you notice fouling, thoroughly clean the
glass immediately.
3.4 Filter
Caution
See also section 3.1 General instructions.
By appropriately setting the air handling unit control system, make sure that the relative humidity in the
second filtering stage does not exceed 90% and the relative humidity in the first filtering stage or in the
stage upstream thereof does not exceed 80% for three consecutive days.
Irregular replacement of filter cartridges causes dust to enter unit and its components. As a result, the
effectiveness of the operation is reduced and damage to the device and system can occur.
•
For smooth operation, inspect the filter medium and replace the cartridges in good time. The frequency of changing
the filter medium depends on the air flow, air pollution and the degree of filtration of the filter medium.
•
Replace all the filters of a particular filter stage or filter unit at the same time. Replacement of an individual filter in a
filter stage is only allowable in the event of filter damage, provided that no more than 6 months have passed from
the previous replacement.
•
The pressure difference in front of and behind the filter medium must not be more than 30 Pa above the
recommended final value.
•
Following insertion into the filter frame, filter cassettes must not be damaged.
•
When replacing the filters, be careful not to contaminate the new filters with dust from old filters or in any other
manner.
•
Store new filters such that they are protected from dust and against damage.
•
Do not use filters whose shelf life, as specified by the filter manufacturer, has expired.
•
Only use filters that are in compliance with the EN 16890-1 standard, as demonstrated by the manufacturer.
•
Handle contaminated filters in accordance with environmental protection regulations.
•
In the case of outdoor-type air handling units, the filter in the first filtering (pre-filter) stage may become clogged
by snow in extreme weather conditions. Filters may also freeze. In such an event, immediately clean or replace the
filters.
• In order to measure the pressure drop, apply the following instruments: A U tube, inclined tube manometer or an
electronic manometer with acoustic or light signalling. Connect the manometers to the measurement ports upstream
of and downstream of the filter, which are provided on the service side on the section external wall, except in the
case of outdoor-type air handling units, where these ports are provided inside the casing.
• Keep the inner and outer surface of the inspection glass clean. If you notice fouling, thoroughly clean the glass
immediately.
•
Insert only clean and undamaged filters.
Comparison of minimum filter classes between EN 779 and ISO 16890 and values of recommended final pressure drops:
EN 779
ISO 16890
G4
coarse 60%
M5
ePM10 60%
M6
ePM2,5 50%
F7
ePM1 60%
F8
ePM1 75%
F9
ePM1 85%
Filter class
Recommended final pressure
drop (lower value)
ISO coarse
50 Pa + starting pressure drop
or 3x starting pressure drop
ISO ePM1
100 Pa + starting pressure drop
or 3x starting pressure drop
ISO ePM2,5
ISO ePM10
Filter class
Recommended final pressure
drop
G1 - G4
150 Pa
M5 - F7
200 Pa
F8 - F9
300 Pa
E10 - H13
500 Pa