Gardner Denver L55 Troubleshooting guide

Original User and Service Manual
Screw Air Compressor
L55 - L75
L55RS - L75RS
USA 13-21-605 VERSION: 00

August 20, 2018 1
General Information
These compressors are designed for compressing atmospheric air and are not suitable for compressing any other gas.
They are designed and manufactured to give optimum performance with long life and reliability.
This manual gives the user allthe information required to install, commission and operate the compressors and carry out
the regular schedules for servicing and maintenance which will ensure a maximum satisfactory service life.
Servicing facilities and the supply of genuine replacement parts are provided through a worldwide network of Gardner
Denver distributors. For individual replacement parts, please contact your local Gardner Denver office or your dealer.
The information in this manual was valid at the time of publication. However, because modifications to parts and
procedures may be made at any time which could affect the servicing requirements of the compressors, always make
sure that the very newest information is at hand before the compressors are serviced. New and edited publications can
be obtained from your local Gardner Denver distributor or service center.
In any communication concerning the compressor it is essential to quote the MODEL and SERIAL NUMBER.
In this manual all pressures quoted are gauge pressures unless otherwise stated.
Maintenance
To ensure the continued trouble-free operation of the compressor it is important that periodic maintenance and servicing
are carried out in accordance with the information given in the ‘Maintenance’section of this manual. If you require
assistance, please contact your local Gardner Denver business or Gardner Denver dealer. They can offer you a number
of optional maintenance agreements suited to your requirements. These agreements provide the operator with expert
knowledge from our trained technicians and the guarantee that only genuine Gardner Denver parts will be used.
Warranty
The conditions of the Gardner Denver Warranty are set out in the company's standard Conditions of Sale available from
the Distributor supplying the machine.
USE ONLY GARDNER DENVER GENUINE PARTS. USING NON-GENUINE PARTS
FOR SERVICING OR REPAIRS WILL INVALIDATE YOUR WARRANTY.

2 August 20, 2018
1 Warning -Prohibition - Mandatory Label Information
Gardner Denver Rotary Screw compressors are the result of advanced engineering and skilled manufacturing.
To be assured of receiving maximum service from this machine, the owner must exercise care in its operation and
maintenance. This book is written to give the operator and maintenance department essential information for day-to-day
operation, maintenance and adjustment. Careful adherence to these instructions will result in economical operation and
minimum downtime.
Boxed text formats are used within this manual to alert users of the following
conditions:
Safety Labels are used within this manual and affixed to the appropriate areas of the
compressor package to alert users of the following conditions:
DANGER
Indicates a hazard with a high level of risk, which if not avoided, WILL result in death or serious
injury.
Pressurized part or system This system can start up by means of a remote control or
automatically after a power failure.
The system continues to run for 30 seconds after
pressing the O-key
Danger of electric shock

August 20, 2018 3
Check and, if required, re-tighten connection terminals.
For further details, see the operating instructions.
Danger of electric shock from loaded condense
rs! Please
always first disconnect the system from the power supply
and wait another 10 minutes before touching the
electrical components. The power condensers require
this time in order to discharge!
Check the DC bus voltage at the system terminal strip of
the frequency converter by measuring this between the
+DC and -DC terminals (the exact position can be found
in the supplied operating manual of the frequency
converter), betweenthe +DC terminal and the chassis as
well as between the
-DC terminal and the chassis.
The voltage must read zero in the case of all three
measurements.
WARNING
Indicates a hazard with a medium level of risk which, if not avoided, COULD result in death or
serious injury.
CAUTION
Indicates a hazard with a low level of risk which, if not avoided, MAY result in a minor or moderate
injury.
Burn Hazard –Hot surface
NOTICE
Indicates a property damage message.

4 August 20, 2018
PROHIBITION/MANDATORY ACTION REQUIREMENTS
Asphyxiation Hazard –Never breathe in compressed air
from this system.
Never operate the unit with open doors or loose access
panels.
Read the operator’s manual before proceeding with this
task
Opening pressure relief valve = xx bar (value "xx" see
sticker on compressor)
Handle package at forklift points only Before disassembling the tube bundle, the intake union
must be disassembled! (Only for water-cooled units)

August 20, 2018 5
2 Preface
Fig. 1
Your Gardner Denver distributor
Name:
Address: _____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
Telephone: Fax:
Contact: Spare Parts:
Service:

6 August 20, 2018
2.1 Compressor Information
Gardner Denver screw compressors are the result of
many years of research and development. This
background and a high-quality standard ensure that the
screw compressors we manufacture have long service
lives with higher reliability and economic operation.
Naturally, we also ensure that strict environmental
protection requirements are met.
2.2 Intended Use
The machine/equipment is built with state of the art
technology and following recognized safety regulations.
However, the use of the machine can result in serious
injury or death to the user or third parties, or cause
damage to the machine or other valuables if:
·it is not used as intended
·it is operated by untrained personnel
·it is improperly changed or modified
·the safety instructions aren’t observed.
Therefore, everyone who is involved in operating,
servicing or repairing the machine must read and
follow the safety rules. If necessary, this must be
confirmed with a signature.
Naturally it is also necessary to follow:
·relevant accident prevention rules
·generally accepted safety rules
·country-specific regulations
The machine/equipment may only be used if it is in
good working order. Always be aware of safety and
potential dangers and only use the machine/equipment
as directed in the user manual. In particular, faults
which could affect safety must be dealt with promptly.
The machine/equipment is intended only for creating
pressurized air to drive pressure equipment. Any other
or extended use is not considered to be an intended
use and the manufacturer/supplier shall not be held
liable for any resulting damages. The user shall bear
such risks alone.
Following the user manual as well as inspection and
maintenance requirements are also considered to be
part of proper use.
2.3 Maintenance and Care
Proper maintenance and care are necessary to ensure
that the screw compressor fulfills the requirements
made of it. Therefore, it is essential that the prescribed
maintenance intervals are adhered to and that
maintenance and upkeep are done thoroughly,
especially under difficult operating conditions.
Service
If you encounter a fault or require spare parts, please
contact your Gardner Denver representative. Trained
expert staff will quickly and properly make repairs with
genuine Gardner Denver replacement parts. Genuine
Gardner Denver replacement parts are manufactured
with state-of-the-art technology and guarantee reliable
operation.
For important questions
Please enter the date from the nameplate of your unit
into the nameplate shown (fig.1 on p. 5). With inquiries
or when ordering replacement parts, please list the
compressor type, the ID number, and the year of
manufacture as listed on the nameplate. Providing this
information helps to ensure that you will receive the
right information or the necessary replacement part.
2.4 Notes
General Notes
This user manual should help you to get to know the
machine/equipment and to make use of its possible
approved applications. It contains important notes on
how to operate the compressor in a safe, proper and
economic way. Following these instructions helps to
avoid dangers, minimize repair costs and downtime and
increase the reliability and service life of the
machine/equipment.
The user manual should be supplemented with
instructions based on existing national regulations on
accident prevention and environmental protection. It
must always be available at the location where the
machine/equipment is used. The user manual must be
read and used by everyone who works on/with the
machine/equipment. For example when: servicing,
including setup, troubleshooting during operation,
eliminating production waste, care, disposing of
lubricants and additives, performing maintenance and
repairs (servicing, inspection, repairs), transporting.
Aside from the user manual and respective national and
local regulations for accident prevention, recognized
rules for safety and proper working methods must be
followed.

August 20, 2018 7
Warranty
You should only use the compressor after first fully
learning its operation and in accordance with this
manual.
Gardner Denver will not guarantee the safe operation of
the machine/equipment if it is not handled in a way
which corresponds to accepted use or if it is used for
other applications which are not named in the manual.
You have no right to warrantee claims in case of:
·user errors
·inadequate upkeep
·the use of improper fuel
·failing to use genuine Gardner Denver replacement
parts
·alterations to the equipment.
The warrantee or liability terms of Gardner Denver’s
Terms and Conditions are not expanded by the
foregoing.
Any independent alterations to the compressor
equipment/station or installing components which have
not been approved by the manufacturer (e.g.,
separator) will result in the loss of the CE mark, or other
factory certifications. As a consequence, all liability and
warrantee claims against the manufacturer will be
terminated.
Safety Regulations
DANGER
Always observe the safety regulations in
Section 4 of the user manual.
Technical Changes
We reserve the right to make changes in the course of
technical development without prior notice.

8 August 20, 2018
3 Table of contents
1 Warning -Prohibition - Mandatory Label Information ..................................................................................... 2
2 Preface ............................................................................................................................................................ 5
2.1 Compressor Information ......................................................................................................................... 6
2.2 Intended Use.......................................................................................................................................... 6
2.3 Maintenance and Care............................................................................................................................ 6
2.4 Notes..................................................................................................................................................... 6
3 Table of contents............................................................................................................................................. 8
4 Safety regulations ......................................................................................................................................... 10
4.1 General safety regulations .................................................................................................................... 10
4.2 Particular dangers associated with compressed air................................................................................ 11
4.3 Particular dangers associated with machines......................................................................................... 13
4.4 Particular dangers associated with water-cooled units ........................................................................... 13
4.5 Dangers present when loading/moving machines .................................................................................. 14
4.6 General workplace dangers.................................................................................................................. 14
4.7 Dangers resulting from neglecting to perform maintenance.................................................................... 15
4.8 Dangers during maintenance and repairs.............................................................................................. 16
4.9 Dangers resulting from conversion work/modifications on the machine................................................... 17
5 Design and functioning ................................................................................................................................. 18
5.1 Design of the unit ................................................................................................................................. 18
5.1.1 Design of air-cooled units ............................................................................................................. 18
5.1.2 Design of water-cooled units......................................................................................................... 20
5.2 System Schematic................................................................................................................................ 21
5.3 Oil circuit.............................................................................................................................................. 22
5.4 Air circuit.............................................................................................................................................. 22
5.5 System control ..................................................................................................................................... 22
5.5.1 System control L55-80.................................................................................................................. 22
5.5.2 System control L55RS-L75RS ...................................................................................................... 23
6 Transport and installation ............................................................................................................................. 26
6.1 Transport ............................................................................................................................................. 26
6.2 Installation............................................................................................................................................ 27
7 Preparations for commissioning .................................................................................................................. 28
7.1 Cooling air volume/minimum cross........................................................................................................ 28
7.2 Compressed-air connection .................................................................................................................. 29
7.3 Water connection for water-cooled units................................................................................................ 30
7.3.1 Limit values of the constituent elements in water........................................................................... 31
7.4 Electrical connection (USA/CANADA Version only)................................................................................ 31
7.4.1 Check setting of the fan protection switch (only for L55RS-L75RS) ................................................ 33
7.4.2 Checking the setting of the control-power transformer.................................................................... 33
7.5 Checking the Oil Level.......................................................................................................................... 33
7.6 Sound pressure level............................................................................................................................ 34
8 Commissioning ............................................................................................................................................. 35
8.1 First commissioning.............................................................................................................................. 35
8.2 Putting a decommissioned compressor back into operation.................................................................... 37
8.3 Display of the compressor control GD Pilot TS ...................................................................................... 37
8.4 Routine commissioning......................................................................................................................... 37
8.5 Commissioning after malfunction........................................................................................................... 38
8.6 Shutoff................................................................................................................................................. 38
8.7 Emergency stop ................................................................................................................................... 38
9 Storage of compressors................................................................................................................................ 39
9.1 Decommissioning................................................................................................................................. 39

August 20, 2018 9
10
Service and maintenance .............................................................................................................................. 40
10.1 Maintenance recommendations ............................................................................................................ 40
10.2 Maintenance Electric Motor................................................................................................................... 40
10.2.1 Motor Lubrication ...................................................................................................................... 40
10.3 Maintenance and inspection schedule................................................................................................... 41
10.3.1 Service Check List .................................................................................................................... 41
10.4 Oil change............................................................................................................................................ 45
10.5 Change oil filter cartridge...................................................................................................................... 46
10.6 Changing the fine oil separator.............................................................................................................. 47
10.7 Change of air intake filter...................................................................................................................... 48
10.8 Pressure relief valve............................................................................................................................. 49
10.9 Connecting terminals in the switch cabinet/control transformer setting.................................................... 49
10.10 Screw connections ............................................................................................................................... 51
10.11 General maintenance and cleaning....................................................................................................... 51
10.12 Clean / change filter with cool air intake and control box filter pads......................................................... 51
10.13 Clean dirt interceptor (only for water-cooled units) ................................................................................. 52
10.14 Inspection intervals for pressure reservoir and electrical installations...................................................... 53
10.15 Maintenance notes and lubricant recommendations for stationary compressors...................................... 53
11 Trouble-shooting ........................................................................................................................................... 54
12 Annex ............................................................................................................................................................ 56
12.1 Technical specifications........................................................................................................................ 56
12.1.1 USA/CANADA version L55-L80 A - air cooled............................................................................ 56
12.1.2 USA/CANADA-Version L55 RS A - air cooled ........................................................................... 57
12.1.3 USA/CANADA version L75RS A - air cooled.............................................................................. 58
12.2 Layout plan .......................................................................................................................................... 59

10 August 20, 2018
4 Safety regulations
4.1 General safety regulations
Danger Safety measure required
Working with compressors involves
dangers that are not immediately
apparent.
Everyone working with the machine must have first read and understood the
operating manual. Don’t leave this until you start work –it’s too late.
Please keep this operating manual handy at all times on the site of the
machine / installation, in the bag provided.
Pay attention to all safety and danger warnings on the machine/ installation!
Deploy trained staff only. The responsibility of the personnel for operating,
setting up and maintaining the machine / installation must be clearly defined.
Make sure that only authorized personnel use the machine.
Define who is responsible for operating the machine, and authorize him/her to
ignore instructions from third parties if these instructions could compromise
safety.
Symbols on the machine indicating
dangers may become dirty or
disappear.
Ensure that all safety and danger notices on the machine/system stay fully
legible.
Faults and modifications to the machine
may jeopardize safety. In the event of malfunctions, shut down the machine/system immediately and
secure it from being switched on again! Have malfunctions corrected
immediately.
Check the machine / installation for external damage and faults at least once
per shift.
Any changes noticed (including changes in operating performance) must be
reported immediately to the authority or person in charge. If necessary, shut
down and secure it from being switched on again.

August 20, 2018 11
4.2 Particular dangers associated with compressed air
Danger Safety measure required
Compressed air is very powerful. It can
be used for example to break open
concrete but can also put lives at risk.
Never play about with compressed air.
Small parts propelled at high speed by
compressed air can penetrate the skin
or destroy an eye.
When using compressed air to clean equipment, work with extreme caution
and always wear suitable eye protection.
Never direct compressed air onto the skin or toward another person.
Never use compressed air for cleaning clothing.
Compressed-air connections may split
and put people at risk. Only connect the compressor to the existing compressed-air system when the
service temperatures and service pressures are correct and the connecting
flange and connecting thread are in full working order.
All connected components must be of the correct size and be suitable for the
specified operating pressure and temperature (i.e. distributing pipes and pipe
connections).
A hose connected to an air valve must be fitted with a safety wire for
operating pressures above 102 PSI; it is in fact recommended that this safety
device should be used for pressures above 58 PSI. The steel wire has a
diameter of 0.315" and is firmly clamped to the hose at least every 20". Both
ends are fitted with cable lugs.
Do not use chafed, damaged or poor-quality hoses.
Only use the correct type and size of hose coupling and connection.
The compressed-air line connected at the air exit of the unit must not be
under strain.
No force should be applied to the outlet thread or the outlet flange by, for
example, pulling on the lines or by mounting additional equipment
(e.g., a water separator or a pneumatic oiler, etc.)
Compressed-air lines may be breached
by accident. Compressed-air lines have to be marked distinctly according to local regulations.
Compressed-air lines get hot and
expand. Make sure that the compressed-air line from the compressor to the air
network can expand as a result of heat and cannot come into contact with
inflammable materials.
Pipes and other parts with a surface temperature of more than 158 °F must
be suitably secured against contact and suitably marked.
Loose hose ends may flog and result in
injury. Fix the hose in such a way that it does not lash if the connection is broken.
Before blowing through a hose or air line, it is essential to hold the open end
firmly.
Before disconnecting a hose, always make sure that it is not under pressure.

12 August 20, 2018
Danger Safety measure required
Compression results in high
temperatures. Risk of explosion from
drawn in materials.
The system should be set up such that hazardous mixtures (inflammable
solvent vapors etc. but also dusts and other dangerous or toxic materials)
cannot be drawn in. The same applies to flying sparks.
Never use the machine in environments where the possibility cannot be ruled
out that inflammable or toxic vapors may be taken in.
The installation is to be set up in such a way that it is adequately accessible
and that the necessary cooling is ensured. Never block the admission of air.
Compressor units must never be operated in areas subject to explosion
hazards! (Exception: Special units with the corresponding technical
modifications)
There is strong suction at the air inlet. The air intake is to be designed in such a way that no loose clothing can be
drawn in.
There is a risk of injury, e.g., from
getting stuck or being drawn in. Personnel must not have long, loose hair, or wear loose clothing or jewelry,
including rings, due to risk of injury through catching. Personal protective
equipment should be worn if necessary.
Connected compressed air tools may
start up unexpectedly when switching
on.
Before switching on the machine / installation, or starting it up, make sure that
nobody can be injured by the machine / installation as it starts up.
Compressed air may contain
substances that may damage your
health if inhaled.
The compressed air produced by these compressors must not be used as
breathable air, unless it has been processed specially for such an application
in accordance with the “Safety requirements for breathable air.”
When breathing apparatus with cartridges is used, make sure that the correct
cartridge has been inserted and that its service life has not expired.
The pressure relief valves in the system
only guarantee the pressure relief for
the compressor unit.
The pressure devices/systems connected to the compressor must be secured
allowing for the weakest pressurized component (pressure relief valve or
similar).
As a rule: If several compressors are arranged in a system, manually operated valves
have to be installed so that each machine may be shut off individually. For the
purpose of shutting off pressurized systems, you should never rely on the
effectiveness of return valves alone.
All pressure tanks located outside the unit with an approved operating
pressure higher than atmospheric pressure and fitted with two or more
pressure feed lines must be equipped with an additional safety device to
automatically prevent the approved operating pressure from being exceeded
by more than 10%.
Never operate the system at temperatures and/or pressures below or above
the values indicated in the technical data sheet.

August 20, 2018 13
4.3 Particular dangers associated with machines
Danger Safety measure required
Risk of electric shock. Electrical connections must meet the local regulations. Power units must be
connected to earth and protected from short-circuits by means of fuses.
Insufficient power quality could have
a strong effect on health & safety and
may constitute a risk to life and limb
of the user or third parties.
Always check a correct power supply to the compressor before commissioning.
The voltage supply has to fulfill the requirements of EN60204-1/IEC60204-1 for
such kind of industrial equipment.
Remote-controlled units may start up
unexpectedly. If a remote control is used, the system must carry a clearly visible sign with the
following note: Attention! This installation is operated by remote control and can
start up without prior warning!
As an additional safety measure, persons who start remotely controlled systems
have to take sufficient safety precautions in order to ensure that nobody is
checking the system or working on it. For this, a label with a corresponding
warning notice has to be attached to the remote control equipment.
Noise, even when it is not very loud,
can make us nervous and irritated,
and after a longer period of time our
nervous system can suffer serious
damage.
We recommend a separate machine room in order to keep the noise of the
machine away from the workshop.
Where necessary, wear the personal hearing protection.
In order to consider all noise-relevant parameters and to adequately protect the
health of the operator, the European Regulation 2003/10/EC must be satisfied
completely by the user. In states outside the European Union, the respective
noise protection directives must be taken into consideration.
Shielding and doors must be closed during operation so that the efficiency of the
sound insulating is not reduced.
4.4 Particular dangers associated with water-cooled units
Danger Safety measure required
If open cooling towers are used in the
cooling water circuit, it is possible for
legionella (Legionella pneumophila)
and other bacteria to grow and
spread.
The growth and spread of bacteria must be prevented by corresponding service
and water treatment methods.
As a result of leakage in oil/water
coolers, some oil may get into the
cooling water circuit.
Have the cooler checked regularly by specially trained technicians.
Strictly observe the relevant wastewater regulations.
Cooling water must not be drained in an uncontrolled manner into public sewage
systems.
Uncontrolled overflowing of the oil separation reservoir into public sewage
systems must be ruled out.

14 August 20, 2018
4.5 Dangers present when loading/moving machines
Danger Safety measure required
Loose parts may fall off when lifting. All loose parts must first be removed or secured; parts fitted so that they can
turn like doors etc. must be secured and made immobile.
Partsto be removed for transport purposes must be carefully refitted and
fixed again before putting the machine / installation back into operation.
The compressor may fall if mistakes are
made when lifting. Only use lifting tackle approved for the weight in question.
Observe the operating manual for the lifting tackle.
When heavy loads are being conveyed by means of hoisting gear, it is
imperative to keep well clear of the load in order to avoid accidents.
The person giving the instructions must be within sight or voice contact with
the operator.
Safety components may be damaged if
lifted incorrectly. Machines may only be hoisted correctly using hoisting gear in accordance
with the information in the operating man
ual (lifting spots for heavy-lift
facilities etc.)
To avoid damage to the system or external installations, the compressed-air
connection, cooling water connection, condensation drain and electrical
connection should be isolated from external lines and hoses.
The system must be set up on a level surface with full contact between its
base frame and the supporting surface.
4.6 General workplace dangers
Danger Safety measure required
This manual only describes how to work
safely with the compressor itself. But
other dangers will arise during work.
Please note and pass on general statutory and other binding regulations that
may supplement the operating manual for the prevention of accidents and the
protection of the environment. Such obligations may be for example the
handling of hazardous materials, or the provision and/or wearing of personal
protective equipment, or traffic regulations.
Instructions, including supervisory responsibility and duty of notification for
taking account of special in-plant factors, for example regarding work
organization, sequences of operations, personnel assigned to certain tasks,
are to be added to the operating manual.
Before starting work, make yourself familiar with the working environment at
the installation site.
The location and operation of fire extinguishers must be made known.
Observe the instructions concerning fire alarm and fire fighting.
Set up the machine in such a way that no inlets, outlets or gates are blocked.
When handling chemical substances, observe the safety regulations
applicable for the product.
Caution when handling process materials (risk of burning / scalding).

August 20, 2018 15
4.7 Dangers resulting from neglecting to perform maintenance
Danger Safety measure required
Components of importance to safety
wear over time.
Observe the setting, maintenance, and inspection work and intervals
stipulated in the operating manual, including information about the
replacement of parts / partial sections. This work may only be carried out by
specialists.
Observe the intervals stipulated or those given in the operating manual for
routine checks and inspections.
Verify regularly that pressure relief valves and other pressure-relief devices
are in perfect condition and are not blocked, for example by dirt or paint
Check regularly that the safety mechanisms are fully functional. Have
malfunctions corrected immediately.
Lines perish. Check regularly that all hoses and/or pipes within the system are in good
condition, firmly fixed and do not chafe.
Replace hydraulic hose lines at the stated or at reasonable intervals even if
no defects of relevance to safety are apparent!
Spurting oil can result in injuries. Check all lines, hoses, and bolted connections regularly for leaks and visible
damage. Repair damage immediately and always arrange for damaged parts
to be replaced!
Risk of electric shock. Have the electrical equipment on a machine/system checked regularly. Have
defects like loose connections or charred cables rectified immediately.
Use only original fuses with the specified current rating. In the event of faults
with the electrical power supply, switch the machine/system off immediately,
and secure it from being switched on again!
In the event of faulty sensors, the
system can be led into a dangerous
state of operation.
Check the accuracy of pressure and temperature indicators at regular
intervals. If the admissible tolerance limits have been exceeded, these
devices have to be replaced.

16 August 20, 2018
4.8 Dangers during maintenance and repairs
Danger
Safety measure required
During maintenance and repairs,
parts
that may be pressurized must be
removed. If you maintain the
compressor and have not been trained
by Gardner Denver, you will put yourself
and others at risk.
The compressor can only be maintained by specially trained technicians.
Contact your Gardner Denver agent.
Incorrectly configured spare parts may
jeopardize safety, e.g.,
tear when
loaded.
Spare parts must meet the technical requirements laid down by the
manufacturer. This is always guaranteed when original spare parts are used.
Risk of elect
ric shock.
Work on the electrical systems of the machine
/ installation may only be
carried out by a trained electrician in accordance with electrical regulations.
The system must be secured from being switched on. Seal off the main
switch and remove the key and/or attach a warning sign to the main switch.
L55RS-L75RS only: Danger of electric shock from loaded condensers!
Always first disconnect the system from the power supply and wait another
10 minutes before touching the electrical components. The power condensers
require this time in order to discharge!
Check the DC bus voltage at the system terminal strip of the frequency
converter by measuring this between the +DC and -DC terminals (the exact
position can be found in the supplied frequency converter operating manual),
between the +DC terminal and the chassis as well as between the -DC
terminal and the chassis. The voltage must read zero in all three
measurements.
The machine may start up
unexpectedly.
Only carry out maintenance and repair work when t
he system is not in
operation and the power supply disconnected. Ensure that the power unit
cannot be switched on inadvertently. The system must be secured from being
switched on.
Seal off the main switch and remove the key and/or attach a warning sign to
the main switch.
Risk of injury from pressurized or
moving parts.
Only carry out inspection, maintenance, and repair work when the screw
compressor system is at a standstill and is not under pressure. The system
must be secured from being switched on.
Before removing or opening pressurized components, positively isolate any
source of pressure and depressurize the entire system.
During the course of maintenance and
repairs, parts can be damaged which
are important for safety.
Never weld any pressure res
ervoir or change it in any way.
If work which produces heat, flames, or sparks has to be carried out on a
machine, the adjacent components have to be protected by means of non-
inflammable material.
Motor, air filter, electrical components, and regulating equipment have to
protected from the ingress of humidity, e.g., when cleaning the system by
means of a steam jet.
Under no circumstances must the sound-proofing material be removed or
modified.
Never use etching solvents which could attack the materials used.
Before cleaning the machine with water or steam jet (high-pressure cleaner)
or other cleaning agents, cover/mask all openings which have to be protected
from the ingress of water, steam or detergents for safety and/or functional
reasons, in particular electric motors and switch cabinets. After cleaning,
remove the covers/masking completely.
Modifications to the machine impair
safety.
After completing repair work, always check to see whether any tools, loose
parts or cloths have been left in or on the machine, driving engine or driving
equipment.
After the work has been completed, replace any protective devices that have
been removed. Operation without protective devices is not permissible.
Always re-tighten screwed connections which were loosened for maintenance
and repair work.
Machines performing rotating movements have to be cycled several times in
order to ensure that there are no mechanical faults in the machine or the
drive member.
Before releasing the power unit for operation after maintenance or overhaul,
check that the operating pressures, temperatures and time settings are
correct and that the regulating and shutdown equipment function properly.

August 20, 2018 17
4.9 Dangers resulting from conversion work/modifications on the machine
Danger Safety measure required
Genuine parts are designed especially
for the machine. Modifications may
interfere with safety equipment or give
rise to new dangers for which protection
is not provided.
No alterations, additions, or modifications to the machine may be carried out
with
out the approval of the manufacturer. Unauthorized modifications to the
machine are prohibited for reasons of safety.
Original parts are specially designed for our machines. We must explicitly
point out that parts and special accessories not supplied by us are not
approved by us. Installing or using such products may thus adversely affect
active and/or passive safety.
The manufacturer accepts no liability whatsoever for damage resulting from
the use of non-original parts or special accessories.
This also applies to the installation and adjustment of safety devices and
valves as well as to welding on bearing and pressurized parts
If protective equipment is not
functioning, operating the system may
put lives at risk.
Only operate the machine when all protective devices, shutdown devices,
sound-insulating equipment and extraction equipment are in place and
working.
Safety devices, protective covers, or insulations mounted on the system must
not be removed or modified in any way.

18 August 20, 2018
5 Design and functioning
5.1 Design of the unit
5.1.1 Design of air-cooled units