CONDITIONS OF USE
permissible ambient temperature:
-30 °C … 40 °C (EX motors -20 °C ... 40 °C)
permissible temperature of medium conveyed: -30 °C … 40 °C
Higher temperatures depend on the design size, material, and speed rate and are subject to consultation with the
manufacturers.
The applied materials have good
chemical resistance
against many substances. It should be considered, however, that
evens plastic materials are attacked by certain chemicals. This depends on the following items:
Chemical composition and concentration of medium conveyed
Temperature and time of action
Mechanical loading and residual stress resulting from processing
Many applications in fields such as laboratories and stockrooms for chemicals, in agriculture and damp-loaded processes
led to good results with "standard materials" such as PVC or PPs that can be used without any problem in most cases.
Critical applications may occur in the process-technological industry - surface refinement, pickling plants, process exhaust
air in microelectronics.
For selection of suitable materials the purpose of use of the fan and the type of medium conveyed should be
specified in requests or orders.
Slightly
dust-laden media
can also be conveyed but lead to increased wear.
Notes on
outdoor use:
If possible, fans should not be exposed to intense ultraviolet radiation.
The motor should be protected by a weather hood.
Ambient conditions have to be considered in material selection.
Working range:
The fans show stable operation in the entire range of the characteristic shown. Operation with smaller
volume flows is possible but very ineffective. Use with larger volume flows may lead to motor overload
(type 734 in particular) and must be avoided.
Parallel arrangement: of type 731 is possible in any case, of type 734 after consultation with the
manufacturers only.
Series arrangement:
requires the manufacturers' agreement (increased casing pressures).
SHAFT SEAL
Radial fans VRE with standard design have vanes in far end arrangement and formed on the rear hub protection cap. This
means permanent intake of external air through the minimized gap of the shaft lead-through if
pressure loss on suction end is greater that one third of total pressure loss.
This is the reason why components with high pressure losses such as washers, filters, separators etc. should be arranged,
whenever possible, before the fan, i.e. on the suction side.
SPECIAL DESIGNS and ACCESSORIES
(more details at the end of this brochure)
Cleaning opening, shatter guard, weather hood for motor, various connections for condensate drain, base of stainless
steel, intake and outlet protective grating
Ventilation components:
ducts, elbows, flaps, air hoods, pipe and profiled silencers
Electrical accessories:
repair switches, motor protection switches, pole changing switches, complete fan controls,
frequency inverters (also with pressure and volumetric flow regulation), air flow monitoring.
A shaft seal
is used if this "aerodynamic casing sealing" is
not sufficient. This may happen if, for instance, there is the
risk of aggressive gas escaping with the fan at rest.
The hub body of
special design GD
carries a sealing ring
with axially acting flexible sealing lip.
The counter-runway in the casing wall consists of a material
with good sliding properties (stainless steel or a special
plastic material, the latter in cases of action of hydrochloric
acid, chromic aid, hydrofluoric acid etc.).
This seal is used for high demands on gastightness and in
cases of relatively dry outlet air. It is distinguished by its long
service life.
There are various special seals such as gas shutoff seals,
labyrinth seals etc. for very high demands on tightness, in
particular in cases of high humidity and much condensate.
The manufacturers should be contacted for such
applications.
04
MIETZSCH GmbH Lufttechnik Dresden
Großenhainer Str. 137
01129 Dresden
Fax (0351) 8 58 00 74
http://www.mietzsch.de
Radial fans of plastic materials
Series VRE
direct driven
Technical explanation
impeller hub
casing wall
counter-runway
sealing ring
i_v
re_
en
(
09/
06
)
