Product Function; Main Filtration; Control Filter; Twin Valve Feed Out Device "Tvfd - Nederman FlexFilter EX Manual De Instrucciones

The FlexFilter EX comes equipped with conductive
Bulk-bags (see Figure 4/F) for collecting the materi-
al (included). Other collection methods may be used if
found to be safe in the system risk analysis.
Only use Nederman conductive containers
when collecting combustible material.
Switch for bulk-bag change
This accessory works with the control system to in-
crease efficiency when changing Bulk-bags. It also en-
sures that no unnecessary alarms are triggered if bag
change occurs simultaneously to the control system
trying to operate the TVFD.
Filter alarm
Pressure switch signalling if the pressure over the
main filter exceeds a set value.
Fire alarm
Detects a fire in the filter and signals the control sys-
tem.
Reverse Flow (RF) kit
The Reverse Flow kit has an arrangement of valves
and uses the capacity of the vacuum unit to clean one
filter module while the other remains in normal opera-
tion. RF is suitable for "hard to clean dust", or if the va-
cuum level is insufficient to generate a powerful blast
of air during normal filter cleaning.

8 Product function

8.1 Main Filtration

The filtration process is described in the following
steps 1-5 (see Figure 6).
1 The inlet module separate coarse particles.
2 The coarse particles pass the cone.
3 The coarse particles fall down into the feed out
device (TVFD).
4 Fine dust particles follow the up-going airflow
through the filter unit. The particles are separated
on the outside surface of the filter bags. A long
spiral spring in each filter bag keeps it from flat-
tening as air passes through the bag from outside
to inside.
5 The filtered air leaves the collector.
6 The filtered air continuous through the control fil-
ter.
The pressure drop increases as more fine dust settle
on the filter bags. During filter cleaning, part of the
dust is dislodged and falls down into the collecting
module. It is not desirable to dislodge all the dust. A
certain quantity of fine particles on the filter bags im-
proves particle separation compared to using clean
bags.
FlexFilter EX
Different kinds of dust have widely different proper-
ties. Some kinds are easily cleaned off the filter bags
while others require more powerful cleaning.
FlexFilter EX with standard filter cleaning uses its own
vacuum to generate a short blast of air backwards
through the filter bags. A compressed air cylinder in
the top module opens a disc valve so that atmospheric
air can rush into the collector to neutralize the vacuum
stored inside the collector. The higher the vacuum and
the larger the connected piping system, the more air
will flush backwards through the filter bags and the
cleaning will be more effective.

8.2 Control filter

The FlexFilter EX is equipped with a control filter. The
control filter filters the air after the main filter to en-
sure that no material continues to the suction source
in case of the main filter breakage. The control filter
functions as a safety device and does not increase the
filtration efficiency.
The pressure drop over the control filter is monitored,
and a signal is sent to the control unit if the above-
set value. A pressure difference is preset at 4 kPa /40
mbar / 0.58 PSI. The pressure switch is located in the
control box (see
The different components of the control filter (see
Figure 7) are:
1 Inlet
2 Outlet
3 Housing
4 Vacuum measuring point (+)
5 Vacuum measuring point (-)
6 Ground cable
7 Lid retainers (x4)
8 Frame bracket
9 Filter cartridge

8.3 Twin Valve Feed out Device "TVFD"

The functional description of the TVFD refers to
ure 8/A-C.
A In normal mode the upper valve is open and the
lower valve is closed. Material from the dust col-
lector passes the open valve and is collected in the
airlock between the valves.
B Emptying of collected material begins with the
closing of the upper valve.
C After the complete closing of the upper valve, the
lower valve opens and the collected material is
dropped into the Bulk-bag or container.
The sequence is run in reverse order and the TVFD
returns to normal collection. The feed-out time
and frequency can be adjusted in the control sys-
tem in order to adapt to different material flow. See
Figure 19/2).
EN
Fig-
35