Mietzsch VRE-W, VRE-R Operating Instructions Manual

Direct-driven radial fans Series VRE-W

Belt-driven radial fans Series VRE-R

Contents: 0. Preface to operating instructions

1. Fundamental safety instructions

1.1 Warning symbols

1.2 Application as prescribed

1.3 Organizational measures

1.4 Remaining dangers

2. Transportation and storage

3. Assembly and starting

3.1 Instructions concerning electrical equipment

3.2 Integrating the fan into the plant

3.3 Initial starting

4. Operation and maintenance

5. Repair instructions

5.1 Cleaning

5.2 VRE-W direct-driven fans

5.3 VRE-R belt-driven fans

5.3.1 Replacing the belt

5.3.2 Replacing the motor

5.3.3 Replacing flange and block-type bearings

5.4 Working parts

6. Waste removal

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Grossenhainer Str. 137
D- 01129 Dresden
Phone [phone]
Fax [phone]
e-Mail [e-mail]
Internet http:/www.mietzsch.de

MIETZSCH GmbH Lufttechnik Dresden

OPERATING INSTRUCTIONS

OPERATING INSTRUCTIONS

0. Preface to operating instructions

The present operating instructions are destined to make the users of fans of series VRE familiar with these devices so
that they will be able to apply them as prescribed.
The instructions contain important information for the reliable, appropriate, and economical use of these fans.
Observation of such instructions helps to avoid danger and to reduce repair cost and downtimes.
The operating instructions should permanently be available wherever the fan is applied. They have to be read and
observed by everybody responsible for transportation, assembly, starting, maintenance, and repair of the fans.
Approved technical regulations concerning workmanlike operation in consideration of safety prescriptions have to be
observed in addition to the present operating instructions and valid legal directions for the prevention of accidents.

1. Fundamental safety instructions

1.1 Warning symbols

Notes concerning economical use of the fan

Details on prescriptions and prohibitions aiming at the prevention of personal injuries and
material damages

1.2 Application as prescribed

The fans are made on the basis of the state of the art and approved safety prescriptions. Their use, however, may imply
danger to the user's life and limb and impairment of the machine and of other material values. This means that
application as prescribed and technical reliability are of utmost importance. The users have to consider and observe the
conditions specified hereinafter.
Unless otherwise specified by contractual agreements, these conditions are as detailed in the manufacturers'
prospectus valid at the making of contract.

a. Demands on the conveying medium and on vicinity

 The permissible temperature range to be maintained depends on the fan type, speed rate, and material.
 Chemical resistivity of applied plastics to the conveying medium has to be tested.
 EX-type fans require the ignition temperature and area of explosion risk to be considered. Standard fans with EX-

type motors have no general explosion protection.

 Mass density of the conveying medium has to correspond to that of pure air. The medium must not contain foreign

particles and has to be practically dustless. Higher dustiness or impure gases with the tendency to deposit can be
causes of damages.
Condensate accumulating in the housing must be able to flow out without being inhibited.

 The fan must be arranged that it is free from shocks and vibrations, and it must not be subject to mechanical stress

from outside.

 Check whether the fan is compatible with the environment. This refers above all to the temperature, chemical

resistivity, and explosion risk.

b. Demands on the operating mode

 The speed rate, speed rates or speed ranges for fan operation must not differ from those specified by the

manufacturers.

 Series connection and parallel connection of fans with forward curved vanes (e.g.VRE / 734) and operation with

higher or lower system pressure are impermissible without consultation with the manufacturers.

 Unless otherwise specified, the fan must be run in the specified characteristic range only. Fans with backward

curved vanes (e.g.VRE / 731) permit operation beyond this range which, however, should be avoided for energetic
reasons.

 To avoid escape of conveying medium through the shaft feedthrough, observe the condition

suction side pressure loss 1

>

total pressure loss 3

Special sealing measures should be subject to agreement with the manufacturers.

 Conditions for electrical connection of the electric motor must be observed.
 Speed setting and control are possible with no other fan types and control units than those permitted by the

manufacturers.

Nonobservance of the conditions specified above means violation of rules of application. The manufacturers cannot be
held responsible for damages resulting from such nonobservance.

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1.3 Organizational measures

 All operations with the fan must be carried through by those operators only who are well trained and reliable.
 Operation with electrical units (motors, control and regulating devices) must not be carried through but by qualified

persons (see also DIN VDE 0105 or IEC 364).

 Repairs of explosion-proof fans must not be carried through but by the manufacturers or after consultation with

them.

 Maintenance intervals have to be specified by the user in consideration of use conditions and, if needed, after

consultation of the manufacturers. The fan must be thrown out of operation and repaired in cases of changes that
might affect safety (such as uneven running, abnormal noise, damages and defects that are visible from outside).

 Original spare parts only have to be used for repair.
 Changes of the fan are impermissible if they lead to safety risks.
 The fan must not be thrown into operation unless its state is reliable. This means that all protective and safety

systems (such as electrical motor protection, belt guard, in some cases protective gratings or strainers) have to be
existing and functioning and that the fan has been integrated into the plant as indicated by the project.

1.4 Remaining dangers

 The fans are of reliable design. Their production is supervised by a quality monitoring system. A certain remaining

danger, however, cannot be excluded. This can be caused e.g. by a broken runner, especially in case that the
conditions of application (see Section 1.2) are violated. Consequently, the fan's vicinity must be secured so that
persons and objects cannot be endangered in the case of a possible average.

 A strainer can avoid that housing destruction leads to danger to the vicinity by fragments, to be sure, but it is no

absolute safety in cases of average.

 It cannot be excluded generally that small quantities of the conveying medium escape at the shaft feedthrough so

that suitable safety measures should be taken according to dangerousness of the gas.

 The permissible immission limit for noise specified in relevant prescriptions for labour protection may be exceeded

especially in cases of fans of larger power and arrangement in small and live rooms. Persons in such rooms must
be protected by suitable measures from injuries by noise.

2. Transportation and storage

 Loading work has to be carried through by experienced persons only. Use hoisting means and load take-ups of

sufficient load-carrying capacity. If transporting the fan take it by its steel components only.

 If transporting the fan by crane fasten suitable load take-ups to the base. Larger fans have two bores in their sheet

metal base for fastening load take-ups.
Transportation eyes of the motor must not be used for fan suspension.

 The fan must be transported in its working position (without vibration isolators put underneath) and protected

reliably against getting out of place, tilting, and collision. If selecting means of transportation take care that plastic
fans are susceptible to shocks.

 In the case of outdoor storage protect the motor and fan inside against direct atmospheric influence.

3. Assembly and starting

3.1 Instructions concerning electrical equipment

 The electrical equipment has to be installed by experts according to standards.
 Every motor has to be connected to the power supply system through a motor protection system. Bimetallic

releases have to be set to rated current. In cases of pole-changing motors install either two separate motor
protection switches or a thermal winding protection (PTC resistor --> special design TS).

 If the motor speed rate is controlled by voltage dividers or frequency inverters a conventional bimetallic switch

offers incomplete motor protection only. A thermal motor protection (PTC resistor --> special design TS,
thermocontacts) is necessary in that case. Also the protection by calculation of I²t, which is very often integreated
in frequency inverters, can be used.

 Electrical connection has to be as shown in circuit diagrams in the terminal box or in the installed and wired repair

switch.

 Check the data of electrical connection (voltage and frequency). Supply voltage in cases of star-delta switches

must be the same as the lower voltage on the type plate.

 The fan must not be started before resistance of the winding relative to earth has been measured. Dry the winding

if this resistance is less than 0.5 M .

 Check the direction of fan rotation by briefly starting it. It must coincide with the direction indicated by the arrow on

the fan.

 After starting measure the current taken by the motor.

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