Miele S 140 Operating Instructions Manual page 18

This indicates when the dustbag needs
to be changed.
The attachment used can affect the
function of the dustbag change
indicator. Therefore only test with the
floor attachment fitted.
^ Switch the vacuum cleaner on and
select the highest power setting.
^ Lift the floor attachment off the floor a
little.
If the red marker completely fills the
indicator window, the dustbag must be
changed, even if it is not completely
full.
This indicator measures the air
permeability of the dustbag.
Even if just a few grammes of flour, fine
cement of brick dust are sucked up,
these fine particles can also affect the
permeability of the dustbag, thus
causing the red scale indictor to show
that the bag is "full", athough it is
virtually empty. The dustbag should,
however, be changed in this case, as
the suction power is greatly reduced.
On the other hand the bag may be
bulging with wool or carpet fluff, but the
air permeability may still be high
enough not to activate the red indicator
to maximum. The dustbag should,
however, still be changed.
18
Both these extremes can occur.
Normally, however, common household
dust is composed of carpet fluff, hair
and grit, i.e. a mixture.
The Miele dustbag change indicator is
designed principally to deal with this
kind of use.
1. If you vacuum up a lot of fine dust or
sand:
^ Change the dustbag as soon as the
red scale fills the window, even if the
bag is not full.
2. If you have vacuumed up a lot of
carpet fluff and hair and the dustbag
is full although the indicator only
shows half full (please check
regularly):
^ Change the dustbag.