GEA Grasso Operating Instructions Manual

_551511_om_kas_gbr_1_.doc 1

CO /NH

2 3

Cascade unit

250 - 1000 kW

Operating Instructions

OPERATING INSTRUCTIONS

CO

2

/NH

3

CASCADE UNIT

250 - 1000 KW

2 _551511_om_kas_gbr_1_.doc

COPYRIGHT

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

CO

2

/NH

3

CASCADE 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

CO

2

/NH

3

CASCADE UNIT

250 - 1000 KW

_551511_om_kas_gbr_1_.doc 5

TABLE OF CONTENTS

1 Operating 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 CO

2

refrigerant 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

2 Start-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

3 Description of Design and Function .................................................................................................... 34

3.1 Brief Description...................................................................................................................... 34

OPERATING INSTRUCTIONS

CO

2

/NH

3

CASCADE 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 CO

2

low temperature stage.........................................................................................35

3.2.2 NH

3

high temperature stage .......................................................................................36

3.3 Oil return system......................................................................................................................36

3.3.1 CO

2

circuit oil return system ........................................................................................36

3.3.2 NH

3

circuit oil return system........................................................................................36

3.4 Auxiliary refrigeration unit for CO

2

separator ........................................................................36

3.5 Safety devices...........................................................................................................................37

3.5.1 CO

2

circuit ....................................................................................................................37

3.5.2 NH

3

circuit ....................................................................................................................38

3.6 Monitoring devices ..................................................................................................................38

3.6.1 CO

2

circuit ....................................................................................................................39

3.6.2 NH

3

circuit ....................................................................................................................39

4 Maintenance 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 - CO

2

circuit.............................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 - CO

2

circuit ........................................................................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

CO

2

/NH

3

CASCADE UNIT

250 - 1000 KW

_551511_om_kas_gbr_1_.doc 7

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

CO

2

/NH

3

CASCADE 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 CO

2

/NH

3

cascade, Part 1............................................... 34

fig. 26: Diagram of the main components of the CO

2

/NH

3

cascade, Part 2............................................... 35

fig. 27: Oil fine separation cartridge............................................................................................................ 49

OPERATING INSTRUCTIONS

CO

2

/NH

3

CASCADE 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

CO

2

/NH

3

CASCADE 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

• NH

3

- 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

• NH

3

connection 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

CO

2

/NH

3

CASCADE 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 NH

3

or CO

2

circuit 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 - NH

3

side

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 - CO

2

side

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

CO

2

/NH

3

CASCADE 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

NH

3

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

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

1

Alkylbenzenr

2

Mineral oil

3

Mineral oil with special treatment (hydrotreated oil)

OPERATING INSTRUCTIONS

CO

2

/NH

3

CASCADE 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 PAO

4

46 268 -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

CO

2

circuit

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.

4

Polyalphaolefin

OPERATING INSTRUCTIONS

CO

2

/NH

3

CASCADE 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

CO

2

/NH

3

CASCADE 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

CO

2

/NH

3

CASCADE 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

CO

2

/NH

3

CASCADE 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

CO

2

/NH

3

CASCADE 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

1.6.2.10 Checking 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!

1.6.2.11 Initial 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

CO

2

/NH

3

CASCADE 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).

1.6.2.12 Setting 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!

1.6.2.16 Checking 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

1.6.2.13 Switching on the CO

2

refrigerant pump ON" pushbutton

Press the "CO

2

1.6.2.14 Switching 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 CO

2

The switching operations are analogous to those of

the NH

3

compressor.

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 NH

3

and CO

2

compressor 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

1.6.2.15 Checking the adjustment of the control

slide

Influencing towards Minimum DS6

1. Cascade is running.

2. Select operating mode ”1 (manual + manual)”.

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GEA Grasso Operating Instructions Manual

GEA Grasso Operating Instructions Manual

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