GEA Grasso User manual

_551511_om_kas_gbr_1_.doc 1
CO /NH
2 3 Cascade unit
250 - 1000 kW
Operating Instructions

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
2 _551511_om_kas_gbr_1_.doc
COPYRIGHT
All Rights reserved. No part of this publication may
be copied or published by means of printing,
photocopying, microfilm or otherwise without prior
written consent of Grasso. This restriction also
applies to the corresponding drawings and diagrams.
LEGAL NOTICE
This publication has been written in good faith.
However, Grasso cannot be held responsible, neither
for any errors occurring in this publication nor for
their consequences.

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 3
SYMBOLS USED IN THIS MANUAL
Danger!
This is an important warning. Non-
observance these warnings can cause
accidents with relevant damages on
persons or serious damages on the
compressor or refrigerating plant.
Warning!
Attention! Caution! Important!
Hint!
Tip! Note!

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 5
TABLE OF CONTENTS
1Operating instructions.......................................................................................................................... 10
1.1 Delivery.................................................................................................................................... 10
1.2 Transport and storage ............................................................................................................ 10
1.3 Transport instructions ............................................................................................................. 10
1.4 Installation............................................................................................................................... 10
1.5 Assembly.................................................................................................................................. 11
1.6 Start-up instructions............................................................................................................... 11
1.6.1 Basics ........................................................................................................................... 11
1.6.2 First commissioning..................................................................................................... 11
1.6.2.1 Leak test....................................................................................................... 11
1.6.2.2 Drying, vacuum ............................................................................................ 12
1.6.2.3 Oil charge..................................................................................................... 12
1.6.2.4 Checking the direction of rotation of the driving motor ........................... 15
1.6.2.5 Checking the direction of rotation of the oil pump motor........................ 15
1.6.2.6 Adjustment of oil pressure .......................................................................... 15
1.6.2.7 Mounting the coupling................................................................................ 16
1.6.2.8 Refrigerant charging.................................................................................... 16
1.6.2.9 Operating position of valves ....................................................................... 17
1.6.2.10 Checking the water circuits ....................................................................... 19
1.6.2.11 Initial startup.............................................................................................. 19
1.6.2.12 Setting the setpoint / limit values and safety devices .............................. 20
1.6.2.13 Switching on the CO2refrigerant pumps.................................................. 20
1.6.2.14 Switching on the compressor .................................................................... 20
1.6.2.15 Checking the adjustment of the control slide........................................... 20
1.6.2.16 Checking the control slide adjustment times............................................ 20
1.6.2.17 Automatic mode........................................................................................ 21
1.7 Shutdown in the event of dangerous situations.................................................................... 21
1.8 Switching off ........................................................................................................................... 21
1.8.1 Normal shutdown ....................................................................................................... 22
1.8.2 Shutting down for a lengthy period .......................................................................... 22
1.8.3 Measures during stoppages ....................................................................................... 22
1.8.3.1 Monthly........................................................................................................ 22
1.8.3.2 Four weeks before putting back into service ............................................. 22
1.8.4 Putting back into service after approx 1 year............................................................ 22
2Start-up / Operation of GSC ................................................................................................................ 23
2.1 General Information ............................................................................................................... 23
2.2 Description of the Grasso System Control.............................................................................. 23
2.2.1 View............................................................................................................................. 23
2.2.2 Lamps/ Push buttons .................................................................................................. 23
2.2.3 Operator terminal....................................................................................................... 24
2.2.3.1 Key assignment............................................................................................ 24
2.2.3.2 Open table of contents ............................................................................... 26
2.2.4 Status messages .......................................................................................................... 27
2.3 System description GSC........................................................................................................... 29
2.3.1 Explanation of the system LED................................................................................... 30
2.4 Alarms ..................................................................................................................................... 31
2.4.1 View active alarms and warnings............................................................................... 31
2.4.2 No alarm signal and the compressor will not start.................................................... 31
2.4.3 Restart following Alarms ............................................................................................ 31
3Description of Design and Function .................................................................................................... 34
3.1 Brief Description...................................................................................................................... 34

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
6 _551511_om_kas_gbr_1_.doc
3.1.1 Use ...............................................................................................................................34
3.1.2 Design ..........................................................................................................................34
3.2 Refrigerant circuit ....................................................................................................................35
3.2.1 CO2low temperature stage.........................................................................................35
3.2.2 NH3high temperature stage .......................................................................................36
3.3 Oil return system......................................................................................................................36
3.3.1 CO2circuit oil return system ........................................................................................36
3.3.2 NH3circuit oil return system........................................................................................36
3.4 Auxiliary refrigeration unit for CO2separator ........................................................................36
3.5 Safety devices...........................................................................................................................37
3.5.1 CO2circuit ....................................................................................................................37
3.5.2 NH3circuit ....................................................................................................................38
3.6 Monitoring devices ..................................................................................................................38
3.6.1 CO2circuit ....................................................................................................................39
3.6.2 NH3circuit ....................................................................................................................39
4Maintenance Instruction.......................................................................................................................40
4.1 General Information ................................................................................................................40
4.2 Servicing/maintenance and safety ..........................................................................................41
4.3 Searching for leaks on refrigerant side / leak test .................................................................41
4.4 Vacuating, charging and draining refrigerant and oil............................................................42
4.4.1 Evacuating the refrigerant (see also initial start-up) ..................................................42
4.4.2 Charging with refrigerant (see also initial startup; initial charge with refrigerant)..42
4.4.3 Charging characteristics...............................................................................................43
4.4.4 Draining the refrigerant ..............................................................................................43
4.4.4.1 General notes on draining refrigerant.........................................................43
4.4.4.2 Charging refrigerant.....................................................................................43
4.4.4.3 Connections for draining refrigerant...........................................................44
4.4.5 Venting the refrigerant circuits...................................................................................44
4.5 Charging and draining oil (see also putting into service).......................................................44
4.5.1 General notes on handling refrigerator oil.................................................................44
4.5.2 Check oil level ..............................................................................................................44
4.5.3 Oil filling.......................................................................................................................44
4.5.4 Draining, changing, checking oil .................................................................................44
4.5.5 Used oil ........................................................................................................................45
4.6 Maintenance Work ..................................................................................................................45
4.6.1 General notes...............................................................................................................45
4.6.2 Opening the compressor (see also compressor maintenance instructions)...............45
4.6.3 Dismantling the compressor suction filter (see the compressor maintenance
instructions) .............................................................................................................................46
4.6.4 Replacing the suction filter..........................................................................................46
4.6.5 Changing the suction filter before refrigerant pump - CO2circuit.............................46
4.6.6 Oil change....................................................................................................................46
4.6.6.1 Meaning........................................................................................................46
4.6.6.2 Maintenance Work.......................................................................................47
4.6.6.3 Changing the oil ...........................................................................................47
4.6.7 Replace oil filter ...........................................................................................................47
4.6.8 Changing the filter driers - CO2circuit ........................................................................48
4.6.9 Clutch maintenance.....................................................................................................48
4.6.10 Oil pump maintenance(for external oil pump)......................................................48
4.6.11 Checking the pull-in torques at fastener of fixing base ...........................................48
4.6.12 Changing the oil fine separation cartridges .............................................................48
4.6.13 Finding and fixing leaks.............................................................................................49
4.6.14 Cleaning the heat exchangers (heat-carrier / cooling agent sides) .........................49

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
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4.6.14.1 Chemical cleaning ...................................................................................... 49
4.6.14.2 Mechanical cleaning .................................................................................. 49
4.7 Steps to be followed before starting the system after major repairs ................................... 50
4.7.1 Repair information...................................................................................................... 50
4.7.2 Pressure test, leak test ................................................................................................ 50
4.7.3 Vacuum Test................................................................................................................ 50
4.8 Repair work............................................................................................................................. 50
4.9 Guide to disturbances, their causes and remedies................................................................. 51

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 9
TABLE OF FIGURES
fig. 1: Vacuum required to remove moisture from refrigerating plants .................................................... 12
fig. 2: Motor direction of rotation............................................................................................................... 15
fig. 3: Stop valve opened ............................................................................................................................. 17
fig. 4: Stop valve closed................................................................................................................................ 17
fig. 5: Check valve......................................................................................................................................... 17
fig. 6: Combined stop/ check valve.............................................................................................................. 17
fig. 7: Control valve ...................................................................................................................................... 17
fig. 8: Combined stop/ check valve with integrated control function........................................................ 17
fig. 9: Solenoid valve .................................................................................................................................... 18
fig. 10: Change-over valve............................................................................................................................ 18
fig. 11: oil pressure regulating valve............................................................................................................ 18
fig. 12: Overflow valve, safety valve ............................................................................................................ 18
fig. 13: Pressure controlled check valve ....................................................................................................... 18
fig. 14: Quick acting valve, spring-held........................................................................................................ 18
fig. 15: Charging valve, draining valve......................................................................................................... 18
fig. 16: Service valve ..................................................................................................................................... 18
fig. 17: Oil temperature limiter .................................................................................................................... 19
fig. 18: Temperatur controlled valve ........................................................................................................... 19
fig. 19: Thermostatic expansion valve.......................................................................................................... 19
fig. 20: Solenoid valve plate with throttle screws ....................................................................................... 20
fig. 21: Exterior view GSC............................................................................................................................. 23
fig. 22: GSC operator terminal ..................................................................................................................... 24
fig. 23: "Status messages" display................................................................................................................. 28
fig. 24: Restart following Alarms ................................................................................................................. 32
fig. 25: Diagram of the main components of the CO2/NH3cascade, Part 1............................................... 34
fig. 26: Diagram of the main components of the CO2/NH3cascade, Part 2............................................... 35
fig. 27: Oil fine separation cartridge............................................................................................................ 49

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
10 _551511_om_kas_gbr_1_.doc
At the same time, check the nitrogen filling and
recharge to the specified overpressure of 0.3 bar ...
0.5 bar, if required. Dry nitrogen with a residual
moisture of ≤300 ppm is used for this purpose.
1 OPERATING INSTRUCTIONS
1.1 Delivery
CO /NH
2 3-cascade units are delivered with an inert
gas charge (nitrogen) in the refrigerant circuit. The
heat exchanger connections are closed. Check on
arrival for possible transport damage and report
damage in writing.
Warning!
Cascades are to be adequately protected
from external influences during transport
and storage.
This usually concerns lengthy standing
times outdoors before installation and
putting into service of the refrigeration
plant.
Protect cascades from damage, dirt and moisture
during longer periods of storage prior to
setup/installation.
(check inert gas charge) Grasso recommends the use of plastic
sheeting to cover the whole product.
The compressors of the cascade unit are not charged
with oil, therefore the cascade must not be started
unless properly installed and commissioned. The venting slots of the electric motors
must always be covered!
Dispatch is effected in the type of packing stipulated
in the order. The cascade unit is generally supplied
without packing. 1.3 Transport instructions
Use the four carrier eyes on the base frame as
slinging points for crane transport.
1.2 Transport and storage
Cascades are high-quality products which must be
handled with due care. Protect the equipment from
impacts and put it down carefully.
To prevent damage on piping and components
attach crossbeams to the ropes.
Hint!
When transported by crane, the cascade must have
the same position as in operation. Do not use
attaching points other than those provided for this
purpose.
Pushing and pulling on components or
climbing on the cascade unit or pipes
easily causes damage and should be
avoided at all costs.
All the information needed to manipulate the
cascade is indicated in the "Transport Instructions".
After completion of erection on the foundation, and
prior to starting up the cascade remove the
transport safety devices installed in the works.
Warning!
It is prohibited to sling cascade units to
any fittings or piping or at the eye
screws/carrying ears on compressor,
electric motor or switch cabinet.
The cascade unit should only be stored in closed, dry
rooms if possible. Storage in the open air under a
roof is only permissible for short periods.
Take special care not to attach the ropes near to
small diameter tubing or to damage the same. Use
spacers if necessary.
1.4 Installation
Select the installation site with care so that any
possibly leaking substances do not penetrate the
ground or enter the surface or ground water (Water
Supply Law WHG).
Position the cascade on the transport vehicle such
that it is prevented from sliding and tilting. The
competent staff member or the company is
responsible for ensuring transport safety. The cascade units have to be installed in closed
machine rooms and on a level surface. Provide
enough space for maintenance work.
The storage area of cascades shall be roofed, plain
and paved and secured against access of
unauthorized persons. The cascade must be
protected against knocks and impacts.
Rigid installation
The frame of the cascade unit is placed on
foundation bolts on a prepared foundation.
Turn the shaft of the compressor at least every four
weeks (approx. 1/8 revolutions). The frame must be levelled with suitable shims such
that the coarse alignment (radial and angular

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 11
•CO
misalignment ≤0.25 mm) at the coupling is attained
again.
- vent line
2
•NH3- safety vent line
Then tighten the foundation bolts. •Electrical connection cable (see electrical
connection diagram)
Installation with anti-vibration mounts
The frame of the cascade unit shall be aligned with
the levelling bolts until the coarse alignment (radial
and angular misalignment ≤0,25 mm) at the
coupling is attained again.
1.6 Start-up instructions
1.6.1 Basics
The cascade may only be operated by trained and
qualified personnel who are familiar with the
contents of the user manual for Grasso CO
Unless otherwise required by local conditions, the
permissible ambient temperatures for operation are
+15 to +40°C.
/NH
2 3
cacades.
The safety regulations for refrigerating plants must
always be correctly complied with in order to
prevent operating personnel injuries and damage to
the cascade.
All foundation calculations, the selection of materials
and the soil analysis are owner’s responsibility.
Outside influences (vibrations, jolts) must be
avoided. The cascade is operated from the control panel of
the compressor control.
The unit may only be lifted for alignment by the
mounting rails or by a crane. See to it in this
connection that the cascade is evenly lifted by two
respective smallhoists in the transverse direction
when small hoists are used (e.g. hydraulic hoists).
After the setpoint values have been entered, both
automatic and manual mode are possible.
The compressor control equipment's software and
operating via the terminal are described elsewhere.
1.5 Assembly 1.6.2 First commissioning
Cascades dismantled in the factory for transport and
positioning purposes must be carefully reassembled
at the installation site according to the drawing and
the PID.
The following procedures should be completed in
the sequence in which they are described:
1.6.2.1 Leak test
The separation points (flanged connections) of cold
pipes must be insulated. The necessary safety precautions must be taken
before carrying out the leak test. The leak test is
performed with dried, oil-free air or with dry
nitrogen.
All pipes and electrical cables must be connected so
that no mechanical stresses or strain occurs.
Connecting the pipes To check for leaks, a 3-hour test is carried out with
dry air or dry nitrogen at any overpressure, but not
higher than the allowable operating overpressure of
the cascade.
•Before connecting the pipes, drain the cascade's
nitrogen filling by opening the vent valves.
•All pipe connections are to be made so as to
limit transmission of thermal expansion and
vibration to the cascade as far as possible.
During the 3 hours a pressure drop of 2% is allowed,
whereby fluctuations in the ambient temperature
must be taken into account.
•Rubber expansion joints can be used for water
connections. Warning!
Control devices which may be damaged
at the given test pressure must be
removed or blocked off before the leak
test is performed.
•All pipe connections are to be fitted with fixed
points directly on the cascade.
The following are to be connected
•NH3connection to condenser
•Cooling water for oil cooler A record should be kept of the leak test, in which
the the pressure in the lines to be tested, the
ambient temperature and the temperature outside
in the shade must be entered at hourly intervals.
•Connections for refrigerant-cooled oil cooler
•CO pump discharge line
2
•CO - return line
2

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
12 _551511_om_kas_gbr_1_.doc
After the leak test has finished and it has been
established that the cascade is free of leaks, reinstall
any instrumentation and control devices removed.
Warning!
Check the oil grade to be charged. See
contract / project or Grasso
recommendation.
1.6.2.2 Drying, vacuum
After the leak test has been completed, the system is
evacuated and subjected to a vacuum test for 3
hours. Evacuation is used to remove air and moisture
from the system.
The quantity of oil to be charged for the respective
compressor is given in the compressor
documentation.
During the 3 hour period the vacuum reached may
rise by maximum 5 torr. Warning!
Due to the use of selected components,
the refrigerator oils tend to absorb more
moisture. Therefore, when charging a
compressor the oil should be allowed to
come into contact with air for a short
time only. The contents of an opened
drum have to be used up within one
working day, provided the drum is
properly closed between charging.
fig. 1: Vacuum required to remove moisture from
refrigerating plants
A Vacuum
B Room or wall temperature
After the required vacuum has been reached
measured values must be logged hourly. After the
negative pressure (vacuum) value, the temperatures
in the machine house and the outdoor temperatures
in the shade must be entered in the log. After the
vacuum test the pressure must be equalized with
refrigerant.
Warning!
Shut off the oil pump during evacuation!
1.6.2.3 Oil charge
The compressor is filled (charged) with oil in the NH3
or CO2circuit according to the compressor's user
instructions.
The vacuum present in the cascade unit before
pressure compensation can be utilized for the first oil
charge. A separate oil recharging pump is required
after the pressure compensation and for refilling
with oil.
1.6.2.3.1 Oil charge - NH3side
The connection of the oil draining/oil charging shut-
off valve (090) must be connected with the oil
charging tank.
Switch the valves to the operating position before
charging with oil.
Open the shut-off valve (090) until the oil level has
reached the top third of the oblong sight glass in the
oil separator sump.
The oil separator is generally charged with oil via the
oil cooler.
When charging with oil for the first time, oil must be
charged via the service valve (135) too. To this end
the shut-off valve (065) must then be closed.
1.6.2.3.2 Oil charge - CO2side
The connection of the oil draining/oil charging shut-
off valve (5720) must be connected with the oil
charging tank.
Before charging with oil, switch the valves to the
operating position.
Open the shut-off valve (5720) until the oil level has
reached the top third of the oblong sight glass in the
oil separator sump.
The oil separator is generally charged with oil via the
oil cooler.
When charging with oil for the first time, oil must be
charged via the service valve (5710) too. To this end
the shut-off valve (5305) must then be closed.

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 13
1.6.2.3.3 Permissible oil grades
Special refrigerator oils must be used. The choice of oil grade does not only depend on its viscosity and chemical
properties but on the cascade's operating conditions.
The choice of oil depends on the coolant, viscosity (at least 7 cSt at oil temperature before entering the
compressor), evaporation temperature (pour point) and the oil separation performance requirements.
Hint!
When choosing an oil grade the compatibility of the sealing material for O-rings (elastomer quality)
used in the compressor must be taken into account in addition to the refrigerant used (see
overview).
Not all the oil grades listed can be used in an existing compressor. It is absolutely necessary to
assign the oil grade depending on the elastomer used, even if the refrigerant is the same.
Oil grades are not always compatible with each other (cannot be mixed).
Changing from one oil grade to another can lead to faults in the compressor's operation and to leaks
at the sealing points. The compressor manufacturer must always be asked before changing the oil
grade.
If other oils are used without the compressor manufacturer's written approval, the cascade's
guarantee cover expires.
circuit
NH3
Viscosity
Cooling medium outlet Flash Pour point
Manufacturer Oil grade Basis at 40°C in
temp in °C point in °C in °C
cSt
1
> -20,0 Fuchs-DEA Reniso S68 AB 68 190 -33
> -20,0 Fuchs-DEA Reniso S68 AB 68 190 -33
2
> -20,0 Castrol Icematic 299 M 56 180 -34
> -20,0 Esso Zerice S46 AB 46 172 -36
> -20,0 Shell Shell Clavus G68 M 65 205 -36
> -30,0 Elf Elfrima FR46 M 46 171 -37
> -30,0 Shell Shell Clavus G46 M 44 195 -39
Gargoyle Arctic SHC
424
> -30,0 Mobil AB 32 157 -39
> -30,0 Esso Zerice S32 AB 32 157 -39
3
> -30,0 CPI CP 1009-68 M* 68 226 -40
1Alkylbenzenr
2Mineral oil
3Mineral oil with special treatment (hydrotreated oil)

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
14 _551511_om_kas_gbr_1_.doc
Cooling medium outlet
temp in °C Manufacturer Oil grade Basis
Viscosity
at 40°C in
cSt
Flash
point in °C
Pour point
in °C
> -30,0 Mobil Gargoyle Arctic Oil 300 M 64 202 -40
> -30,0 Esso Zerice 46 M 46 204 -41
> -20,0 Petro-Canada Reflo 68A M* 58 236 -42
> -20,0 TEXACO Capella Premium M* 67 262 -42
> -40,0 Mobil Gargoyle Arctic Oil C
Heavy M 44 187 -50
> -40,0 CPI CP 4600-46 PAO446 268 -51
> -40,0 Mobil Gargoyle Arctic SHC
226E PAO 67 266 -54
> -40,0 Mobil Gargoyle Arctic SHC
326 (NH68 also) AB + PAO 61 211 -54
> -40,0 Castrol Icematic 2294 PAO 69 233 -60
< -40,0 on request only
The screw compressors are fitted in the factory with suitable O-ring elastomers at the sealing points; these are
selected depending on the refrigerant and lubricant.
Refrigerant / oil M AB PAO, M* AB/ PAO
R717 (ammonia CR CR HNBR CR
CO2circuit
Manufacturer Trademark Oil grade O-ring material
Fuchs Reniso TRITON C 170 HNBR
The screw compressors are fitted in the factory with suitable O-ring elastomers at the sealing points; these are
selected depending on the refrigerant and lubricant.
4Polyalphaolefin

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 15
1.6.2.4 Checking the direction of rotation of the
driving motor
1.6.2.5 Checking the direction of rotation of the oil
pump motor
The oil pump is started with the driving motor
electrically blocked (service). The stop valves are in
the operating position.
Warning!
The coupling must not yet connect motor
and compressor!
The direction of the arrow given for the oil pump
must correspond to the direction of rotation of the
electric motor.
•Secure the electric switchgear so as to prevent
the compressor driving motor from being
switched on accidentally. Caution!
Since the slide ring shaft seal of the oil
pump is dependent on the direction of
rotation and can be damaged when this
direction is wrong, checking must be
reduced to a very short running period
(less than 2 seconds).
•With the control slide in the MIN or MAX
position, it should be possible to rotate the
compressor shaft easily and smoothly by hand.
When checking the direction of rotation of the
compressor driving motor pay attention to the
conditions for switching the compressor on.
The adjusted differential pressure between the oil
pump discharge side and the suction side of the oil
pressure control valve is checked with the oil pump
rotating in the correct direction. It must not be lower
than the specified setpoint of 3.5 + 0.5 bar.
While the compressor is not running and the oil has
not yet reached the operating temperature, the
differential pressure can be slightly higher than the
indicated value.
The differential pressure can be changed by rotating
the spindle on the oil pressure control valve. (The
differential pressure is increased by turning it
inwards and vice versa).
fig. 2: Motor direction of rotation
A Compressor
1.6.2.6 Adjustment of oil pressure
B Motor
Before the compressor drive motor and therefore
the unit can be started, the oil pressure must be set
correctly by adjusting the oil pressure regulating
valve (075).
•The compressor driving motor is operated in
star-delta connection for a short period in the
operating mode "1 (manual + manual)". After
that the compressor driving motor has to switch
off. For adjustment only the oil pump must be started.
For units equipped with a Grasso System Control
(GSC) please select operation mode “service mode”.
•If the direction of rotation of the motor is
wrong, it should be corrected while the electric
switchgear is secured to prevent the motor from
being switched on accidentally. The motor must
then idle for at least 1h.
The set value of the oil differential pressure should
be taken from the P+I-diagram of the specific
project. Normally the set value is Δp = 2-3 bar (oil
pressure Pos (110) –discharge pressure Pos (105)).
•The coupling protection must be in place during
this running-in period as required in the labour
safety regulations.
The differential pressure can be changed by rotating
the spindle on the oil pressure regulating valve (the
differential pressure is increased by turning it
inwards and vice versa).
•After checking the direction of rotation of the
driving motor the coupling may be connected
with the motor.

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
16 _551511_om_kas_gbr_1_.doc
Danger! Circuit Item No. charging valve
An oil pressure adjusted too high or too
low can lead also after short operation
time to serious compressor damages or
even to a total breakdown of the
compressor!
NH 2865
3
CO 6865
2
The location of these charging valves is given in the
P+I flow diagram.
In comparison to normal operation conditions the oil
differential pressure can be (at identical opening
level of the valve) slightly higher if only the oil pump
is operated (service mode) or in case the operating
temperature is not reached yet.
Caution!
Mixing even the smallest quantities of
NH and CO
3 2 in the refrigerant cycles
must be avoided under all circumstances!
In this case the oil differential pressure should be
readjusted (according to the value in the P+I
diagram) after start of the unit and reaching of the
operation temperature.
Use top quality (specially cleaned and
dried) NH and CO only!
3 2
1.6.2.7 Mounting the coupling Whenever work is carried out on the parts of the
refrigerating system carrying refrigerant or oil,
extreme caution is required as leaking refrigerant
can cause hazards. Note and observe the refrigerant
safety data sheets.
1. The electric switchgear is secured to prevent it
from being switched on accidentally.
2. Mount the coupling, observe instructions of
separate documentation. For health and safety reasons, safety goggles and
protective gloves must be worn.
3. The values for radial and angular deviations
given in the coupling documentation must be
checked and if necessary corrected. Refrigerant charging procedure
Equipment required:
4. The real values have to record at data sheet of
coupling documentation. Please send back a
copy of the filled data sheet to: —Refrigerant filling cylinder with liquid connection
—Weighing scales for refrigerant cylinder
Grasso GmbH RT —Special filling hose with cylinder connection
Holzhauser Straße 165 —Shut-off valve with connection adapter for the
charging valve
13509 Berlin, GERMANY
Fax: +49 (0)30 - 43 592 759 When charging for the first time, weigh the quantity
of refrigerant given on the cascade's name plate. To
do this, place the refrigerant cylinder with sufficient
refrigerant on weighing scales. Before starting to
charge, determine the weight of the cylinder.
Caution!
Pay attention to maintenance
instructions!
Regreasing the coupling (if provided for
in the maintenance instructions for the
coupling)!
Connect the filling hose to the refrigerant cylinder.
Warning!
The compressor must be ready for
refrigerant charging!
1.6.2.8 Refrigerant charging
After evacuating the refrigerant circuits, the system
can be charged with refrigerant via the refrigerant
charging valve and then the vacuum can be broken.
1. Connect the refrigerant reservoir to the charging
valve.
2. Open the charging valve.
The refrigerant circuits are only charged via the
charging valves of the respective circuit. 3. Carefully open the reservoir valve and equalize
the pressure.
4. Close the valve.

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 17
5. Check the system again for leakages. Caution!
6. Start the compressor. Flow direction: from A to B and C
7. Open the reservoir valve.
8. Draw refrigerant into the circuit at a low
compressor delivery rate. stop valve
Valve opened during normal operation
At the same time, continuously check the weight
change in the filling cylinder.
Warning!
fig. 3: Stop valve opened
Only fill the quantity specified,
otherwise there is risk of
overcharging the circuit.
Valve closed during normal operation
9. Close reservoir valve when the suction pressure
nears the required values. Let the compressor
continue to run until the refrigerant has been
completely distributed in the circuit. Based on
the values, you can now assess whether
additional refrigerant has to be charged or not.
fig. 4: Stop valve closed
Check valve
Check valve during normal operation
Hint!
If necessary, repeat the "refrigerant
charging" process until the suction
pressure reaches the required value.
fig. 5: Check valve
10. After the charging process has been completed,
close the charging valve and cylinder valve. Combined stop/ check valve
Combined stop/check valve opened during normal
operation
11. Drain and dismantle the charging line.
Now lift the hose to make liquid refrigerant flow
back into the cylinder.
Before dismantling the charging line, carefully
drain the gaseous contents of the hose into a
water receiver in accordance with the safety
regulations.
fig. 6: Combined stop/ check valve
Control valve
Small quantities of refrigerant gas may escape. Control valve adjusted at:
1.6.2.9 Operating position of valves —Commissioning
For the positions of the manually controllable fittings
for the operation of the CO —changed operating conditions
/NH
2 3-cascade unit see
P&I diagram.
The layout and symbols used in the R+I flow charts
comply with the specifications of EN 1861, Issue April
1998.
fig. 7: Control valve
Combined stop/ check valve with integrated
control function
Danger!
The valve positions must match the
specifications given in the R+I flow chart
to ensure trouble free operation!
Combined stop/ check valve with integrated control
function opened during normal operation
fig. 8: Combined stop/ check valve with integrated control
function

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
18 _551511_om_kas_gbr_1_.doc
Solenoid valve Pressure controlled check valve
Controlled by Grasso System Control (GSC) controlled self-sufficient
fig. 9: Solenoid valve
Change-over valve
fig. 13: Pressure controlled check valve
Quick acting valve, spring-held
manually operated if necessary
fig. 10: Change-over valve
oil pressure regulating valve
fig. 14: Quick acting valve, spring-held
Δp x,x ± x bar setted control pressure from
reference pressure Charging valve, draining valve
—½“and ¾“connections
—with cap
fig. 15: Charging valve, draining valve
fig. 11: oil pressure regulating valve
Service valve
Danger!
—Connection Rp ¼“
An oil pressure adjusted too high or too
low can lead also after short operation
time to serious compressor damages or
even to a total breakdown of the
compressor!
—For pressure gauges and transducers
Overflow valve, safety valve
fig. 16: Service valve
fig. 12: Overflow valve, safety valve

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
_551511_om_kas_gbr_1_.doc 19
6. The oil heater has sufficiently heated the oil
Oil temperature limiter
Voltage connection
controlled self-sufficient by control element
Before switching on the main switch, all motor
protection switches and bridge fuses within the
cascade must be switched on.
The cascade must be put into service in accordance
with the operating instructions for the compressor
control.
1. Switch on the control voltage of the compressor
control.
2. Acknowledge existing fault indications.
fig. 17: Oil temperature limiter
3. Select operating mode ”1 (manual + manual)”.
Temperatur controlled valve 4. Switch on the cascade.
controlled self-sufficient Switching on the main switch on the switch cabinet
supplies power to all the connected electrical loads
and equipment and the SPC (programmable control)
system, including the control and display unit.
Hint!
We advise switching on the voltage in
good time before an intended startup.
fig. 18: Temperatur controlled valve
Thermostatic expansion valve The oil-fired heating requires a lead time
in order to heat the oil in the
compressor's crankcase to temperatures
above the refrigerant's saturation
temperature. This is intended to prevent
refrigerant condensing in the compressor
and to ensure any refrigerant already in
the oil is evaporated. This ensures
sufficiant viscosity for bearing lubrication
while the compressor starts.
controlled self-sufficient
fig. 19: Thermostatic expansion valve
1.6.2.10Checking the water circuits
Check whether the cooling and cold water pumps
are running and the shut-off fittings in the cooling
water circuit are in their operating positions.
Special features of operating mode 1 "Manual +
Manual"
Manual mode can only be realised under the
supervision of the operating personnel. The control
cycles are to be specified by the owner on their own
responsibility in compliance with the system-specific
control response.
While the unit/ chiller is operating under project
conditions, adjust the cooling water control so that
the condensing and oil temperature lies within the
permissible range.
Caution!
1.6.2.11Initial startup
The following prerequisites must be fulfilled for the
initial start-up:
The cascade is operated manually!
The cascade operates independent of the
temperature and pressure control!
1. Main current supply available and switched on
Safety and monitoring devices are fully
functional!
2. Heat transfer medium and cooling water pumps
are switched on
3. Media flows through the heat exchangers.
4. The valves are in their "operating position"
5. Sufficient refrigerant and oil charge

OPERATING INSTRUCTIONS
CO2/NH3CASCADE UNIT
250 - 1000 KW
20 _551511_om_kas_gbr_1_.doc
3. The maximum end position (100%) must be
reached and signalled on operating pushbutton
switch (capacity increasing).
1.6.2.12Setting the setpoint / limit values and
safety devices
The setpoint and limit values are set according to the
details given in the Control Manual and the project-
related data.
4. The minimum end position (0%) must be
reached and signalled on operating pushbutton
switch (capacity decreasing).
Check the safety device settings.
5. Vent the adjusting device by moving the control
slide to and for about ten times.
Hint!
See parameter list/ list of set values! 1.6.2.16Checking the control slide adjustment times
While the cascade is running, determine the
adjustment times needed when the control slide is
continually moved from the maximum end position
to the minimum end position and back. For the
automatic system to run smoothly, the adjustment
times in either direction must be approximately the
same.
refrigerant pumps
1.6.2.13Switching on the CO2
refrigerant pump ON" pushbutton
Press the "CO2
1.6.2.14Switching on the compressor
Start NH compressor
3
Minimum adjustment time 30 sec.
Press the "Compressor ON" button
The following switching operations are automatically
realised with the compressor startup:
Optimum adjustment time 60 sec.
—Oil-fired heating switched off. The adjustment times are matched by means of
throttle screws mounted on the solenoid valve plate.
—"Oil pressure bypass" timer starts up.
—Minimum output level after reduced-load startup
While the compressor is starting up the following
readings are to be observed on the cascade:
—Suction pressure, final compression pressure and
oil pressure
—Heat transfer medium temperature
—Sign glasses in the evaporator or in the liquid line
and compressor's housing
compressor
Start CO2
The switching operations are analogous to those of
the NH3compressor.
The "Increase output" and "Reduce output"
pushbuttons can be used to reach the project values
and run the cascade in steady state condition.
fig. 20: Solenoid valve plate with throttle screws
The NH3and CO2compressor output levels should be
alternately switched on and off so that, as far as
possible, both run under the same load.
adjustment time ↓
Rotate in clockwise direction
adjustment time ↑
Rotate in anti-clockwise direction
The refrigerant charge must be checked and
recharged if necessary! Influencing towards Maximum DS5
1.6.2.15Checking the adjustment of the control
slide Influencing towards Minimum DS6
1. Cascade is running.
2. Select operating mode ”1 (manual + manual)”.