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scroll for refrigeration LLZ for parallel applications
Application guide
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Danfoss scroll for refrigeration LLZ for parallel applications Application guide

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Application guidelines
Danfoss scroll for refrigeration
LLZ for parallel applications
50 - 60 Hz - R404A - R507
http://cc.danfoss.com
Application Guidelines
Content
General overview .................................................................................................................................4
Benets .......................................................................................................................................................................................................... 4
Oil management concept ....................................................................................................................5
Operating conditions ..........................................................................................................................8
Refrigerants and lubricants .................................................................................................................................................................... 8
System design recommendations ......................................................................................................9
Essential piping design considerations ............................................................................................................................................. 9
Expansion device ..................................................................................................................................................................................... 10
Suction accumulator............................................................................................................................................................................... 10
Suction header .......................................................................................................................................................................................... 10
Oil level regulator .................................................................................................................................................................................... 11
Oil separator / oil reservoir ................................................................................................................................................................... 12
Oil separator / Oil reservoir for active system ............................................................................................................................... 12
Economizer for parallel vapour injection compressors ...........................................................................................................14
Refrigerant charge limits....................................................................................................................................................................... 14
Installation and service .....................................................................................................................15
Piping design ............................................................................................................................................................................................. 15
Wiring and rotation direction ............................................................................................................................................................. 15
Failure analysis .......................................................................................................................................................................................... 15
Sound and vibration management ..................................................................................................16
Running sound level ............................................................................................................................................................................... 16
Ordering information ........................................................................................................................17
Parallel units LLZ013-15-18-24 ..........................................................................................................18
Composition of LLZ013-024 uneven tandem/trio/quadro ......................................................................................................18
Composition of LLZ013-024 even tandem ..................................................................................................................................... 18
Compressor mounting ........................................................................................................................................................................... 19
Suction and discharge connection ................................................................................................................................................... 20
Oil equalisation connection................................................................................................................................................................. 20
3FRCC.PC.032.A4.02
Application Guidelines
General overview
Scope
Benets
The application guidelines describe the operating characteristics, design features and application requirements for LLZ parallel compressors in low temperature refrigeration applications. They apply to both standard and economized compressors.
To ensure proper parallel installation and running conditions, the following recommendations must be followed:
Parallel compressor installation' refers to a system of interconnected compressors with a common suction line and common discharge line. The technique of mounting compressors in parallel is also referred to as manifolding. In a system with only two compressors, this is referred to as a tandem conguration.
The main reason for manifolding is reduced operating cost through greater control of capacity and power consumption. This is achieved by staggering the compressor switch­on sequences that allow the parallel system to match its power with the capacity needed.
• It is essential to follow all the instructions given in these guidelines, the instruction leaet delivered with each compressor and the Selection & Application Guidelines for single compressors.
• For additional system components related to specic application requirements, the supplier's recommendations must always be followed.
A second reason for manifolding is improved part load eciency. In a parallel installation the individual compressor(s) can be switched o while the other compressor(s) keep operating at 100% load. Therefore the part load eciency is very near the full load eciency. Conventional xed-speed compressor unloading methods impose a serious penalty on part load eciency, mainly at low load conditions.
4 FRCC.PC.032.A4.02
Application Guidelines
Oil management concept
Active systems
Suction gas in a hermetic scroll compressor ows via the oil sump,which makes it more dicult to maintain equal pressure in the sumps of parallel compressors. Since oil equalisation usually depends on equal sump pressures, this is a point of special attention. Danfoss Commercial Compressors have developed specially adapted oil management systems which ensure proper
Suction header
Non return valve
Compressor 1
Oil level regulator Oil level regulator Oil level regulator Oil level regulator
Non return valve
Compressor 2 Compressor 3 Compressor 4
oil balancing between the compressors, but it is always recommended to carry out some tests to validate oil balancing in the system.
To ensure suitable oil distribution, both passive and active types of systems are introduced into LLZ compressors.
High pressure
Low pressure
Non return valve
Non return valve
Oil lter
Non return valve
Combined oil separator/reservoir
An active system can oer more exible and ecient oil management. It is highly recommended for manifolding since this positive system increases the reliability of the manifolding conguration. Oil management will be secured mainly by the oil level regulator and the oil separator, which can supply the oil when required. The active system can thus accommodate itself to various oil conditions.
Danfoss has qualied tandem / trio / quadro composition for active systems.
For manifolding with more than two compressors, it is always suggested to use a
suction header. Each compressor will equip the oil level regulator to facilitate the oil level balance.
To avoid refrigerant back ow from high pressure, it is always recommended to have a non-return valve on the discharge line of each compressor, as well as one non-return valve on the outlet of the oil separator in the system to prevent refrigerant migration.
For more details on the oil separator/reservoir and oil level regulator please refer to the “System design recommendation” in this guideline.
5FRCC.PC.032.A4.02
Application Guidelines
Oil management concept
Passive systems
A passive system is an oil management system without any measurement or control devices such as oil level regulators and oil controllers. By contrast, a solution equipped with such measurement or control devices is called an active system.
Non return valve
Oil equalization
line
Compressor 1 Compressor 2
Suction header
Danfoss has qualied only the even tandem (two same compressors) for passive solutions.
To condenser
Non return valve
Oil separator with oating-ball valve
Oil lter
From evaporator
6 FRCC.PC.032.A4.02
Application Guidelines
Oil management concept
This is one of the simplest and cheapest ways of manifolding compressors. It is very popular in air­conditioning applications, but in refrigeration this kind of system needs to be paid special attention due to severe operating conditions.
Danfoss has qualied only the even tandem
(two same compressors) for passive solutions. Compressor sumps and low-pressure shells are interconnected. An interconnecting pipe on the lower part of the compressor (installed on the existing oil sight glass) ensures oil balancing. The suction header design is critical, as it ensures a pressure drop balancing and an equal distribution of oil returning from the system when both compressors are running.
The success of such a system relies very much on the sizing and design of the pipe work, as small dierences in sump pressure can result in signicant oil level variations. This system needs perfect suction tube balancing.
For an LLZ even tandem, oil return can be secured by an oil separator with oat ball valve, which will return the oil to the main suction line. The oil equalisation line goes through the oil sight glass with an adaptor on the standard compressor. To avoid refrigerant back ow from high pressure, it is always recommended to have a non-return valve on the discharge line of each compressor, as well as one non-return valve on the outlet of the oil separator in the system to prevent refrigerant migration.
The following are recommendations from Danfoss application engineering for connecting low temperature compressors using an oil equalisation line system without active control:
• An adequately (generously) sized suction header is needed to provide for equal distribution of returning refrigerant gas and oil to each individual compressor; also the suction header should be installed horizontally.
• To secure sucient oil return to the compressor, Danfoss suggests below dimension requirement of the suction header: H>5D.
D
Main suction line
Height
• The oil equalization tube is recommended to have an outer diameter of ½’’.
• If the unit runs in a very cold situation, both compressors need to be switched on after a period of single running for better oil circulation, especially in low load conditions.
• Care must be taken to mount all the compressors on the same horizontal level and also to provide adequate liquid ood back protection when using this method.
Danfoss could provide piping drawings for even tandem passive system, please contact Danfoss for more information.
7FRCC.PC.032.A4.02
Application Guidelines
Operating conditions
Power supply
Compressor ambient temperature
Operating envelope
LLZ compressors can be operated at nominal voltages as indicated below. Under-voltage and over-voltage operation is allowed within the indicated voltage ranges. In case of risk of
Motor voltage
code 2
Nominal voltage 50 Hz 200-220 V - 3 ph 380-415 V - 3 ph - -
Voltage range 50 Hz 180 - 242 V 342 - 456 V - -
Nominal voltage 60 Hz 208-230 V - 3 ph 460 V - 3 ph 575 V - 3 ph 380 V - 3 ph
Voltage range 60 Hz 187 - 253 V 414 - 506 V 517 - 632 V 342 - 418 V
LLZ scroll compressors can be applied from -35°C to 50°C ambient temperature. The compressors are designed as 100% suction gas cooled without the need for additional fan cooling.
The recommended parallel assemblies design from Danfoss Commercial Compressors have been qualied to ensure there is no impact on the compressor operating envelope.
undervoltage operation, special attention must be paid to current draw. LLZ scroll compressors are available in four dierent motor voltages.
Motor voltage
code 4
Ambient temperature has very little eect on the compressor performance. For detailed information please refer to “the "LLZ application guidelines”.
More details can be found in the “LLZ application guidelines”.
Motor voltage
code 7
Motor voltage
code 9
Refrigerants and lubricants
Discharge temperature protection
High and low pressure protection
Approved refrigerants and lubricants for LLZ single compressors are also allowed for parallel
The discharge gas temperature of each compressor must not exceed 135°C.
DGT protection is required if the high and low-pressure switch settings do not protect
The pump-down pressure switch must have a set point slightly higher than the lowest compressor safety pressure switch set point. The compressor switch must never be bypassed and shall stop all the compressors. The high-pressure safety pressure switch shall stop all the compressors.
Whenever possible (i.e. PLC control) it is recommended to limit the possibility of
Cycle rate limit The system must be designed in a way that
guarantees a minimum compressor running time of two minutes so as to provide for sucient motor cooling after start-up along with proper oil return. Note that the oil return may vary since it depends upon system design.
assemblies. For more details, please refer to the "LLZ application guidelines".
the compressor against operations beyond its specic application envelope.
More details can be found in the “LLZ application guidelines”.
compressor auto-restart caused by LP safety switch settings to fewer than 3 to 5 times during a 12-hour period.
Please refer to the “LLZ application guidelines” for recommended settings.
of the motor-compressor unit. If necessary, place an anti-short-cycle timer in the control circuit, then connect as shown in the wiring diagram in the Danfoss Scroll compressor application guidelines. A three-minute (180-second) time-out is recommended.
8 FRCC.PC.032.A4.02
There must be no more than 12 starts per hour (6 when a resistor soft-start accessory is introduced); a number higher than 12 reduces the service life
Danfoss recommends a restart delay timer to limit compressor cycling.
max. 4 m
max. 4 m
Application Guidelines
System design recommendations
Essential piping design considerations
Proper piping practices should be employed to ensure adequate oil return, even under minimum load conditions, with special consideration given to the size and slope of the tubing coming from the evaporator. Tubing returns from the evaporator should be designed so as not to trap oil and to prevent oil and refrigerant migration back to the compressor during o-cycles.
If the evaporator lies above the compressor, the addition of a pump-down cycle is strongly recommended. If a pump-down cycle were to be omitted, the suction line must have a loop at the evaporator outlet to prevent refrigerant from draining into the compressor during o-cycles.
If the evaporator is situated below the compressor, the suction riser must be trapped to ensure the oil return to the compressor (see g.1).
When the condenser is mounted at a higher position than the compressor, a suitably sized “U”-shaped trap close to the compressor is necessary to prevent oil leaving the compressor from draining back to the discharge side of the compressor during o-cycle. The upper loop also helps avoid condensed liquid refrigerant from
draining back to the compressor when stopped (see g. 2). The maximum elevation dierence between the indoor and outdoor section cannot exceed 8 m. System manufacturers should specify precautions for any applications that exceed these limits to ensure compressor reliability.
Economiser heat exchanger piping shall be arranged in a counter ow of gas and liquid to assure optimum heat transfer and therefore best subcooling eect.
Piping should be designed with adequate three­dimensional exibility (gure 2). It should not be in contact with the surrounding structure, unless a proper tubing mount has been installed. This protection proves necessary to avoid excess vibration, which can ultimately result in connection or tube failure due to fatigue or wear from abrasion. Aside from tubing and connection damage, excess vibration may be transmitted to the surrounding structure and generate an unacceptable sound level within that structure as well (for more information on sound and vibration, see the section on “Sound and vibration management”).
<15 m/s
0.5% >
>3.6 m/s
HP
LP
U-trap
>7.6 m/s
>3.6m/s
Evaporator
To ensure proper refrigerant and oil circulation, the speed limits in all pipes are generally recommended as follows:
• For horizontal/vertical discharge gas velocity: no more than 15m/s;
• For vertical suction gas velocity: no less than
7.6m/s;
Condenser
HP
LP
• For horizontal suction gas velocity: no less than
3.6m/s;
• For horizontal/vertical liquid velocity: around
1.5m/s;
• For suction header gas velocity: no more than 4m/s.
9FRCC.PC.032.A4.02
Application Guidelines
System design recommendations
Expansion device When the parallel installation is serving a single
evaporator system, the dimensioning of the expansion device (thermostatic or electronic) becomes critical and must be made in relation to both minimum and maximum capacity. This will ensure correct superheat control in all situations, with a minimum of 5K superheat at the compressor suction. The expansion device should be sized to ensure proper control of the refrigerant ow into the evaporator. An oversized valve may result in erratic control. Proper selection could imply a slightly undersized expansion valve at full load. This consideration is especially important in manifolded units
Suction accumulator
The refrigeration compressor is designed to compress vapour only. A suction line accumulator prevents compressor damage from a sudden surge of liquid refrigerant and oil that could enter the compressor from the suction line. For low temperature application, suction accumulator is a must unless approved by careful tests under dierent operating conditions.
Selection of a suction line accumulator should be made on the basis of the following three capabilities:
1. The accumulator should have an adequate liquid-holding capacity that can vary with the
where low load conditions may require the frequent cycling of compressors. This can lead to liquid refrigerant entering the compressor if the expansion valve does not provide stable refrigerant superheat control under varying loads. The superheat setting of the expansion device should be sucient to ensure proper superheat levels during low loading periods. A minimum of 5K stable superheat is required. In addition, the refrigerant charge should be sucient to ensure proper subcooling within the condenser so as to avoid the risk of ashing in the liquid line before the expansion device.
system. Normally this should not be less than 50% of the system charge. If possible, this value should be checked based on actual tests.
2. The accumulator should perform without adding excessive pressure drop to the system.
3. An accumulator should have the capability of returning oil at the proper rate and under a range of load conditions.
Guideline of suction accumulator needs to be respected in making a selection.
Suction header
For ecient oil management in parallel systems the oil should return to the compressor at approximately the same rate as it leaves so that an appropriate oil level can always be maintained.
Danfoss recommends an adequately sized suction header which provides equal distribution of returning refrigerant and oil to each individual
compressor. The suction lines from the header towards each individual compressor must be tted into the suction header. This conguration will result in a higher gas velocity at the pick-up tube inlet and proper oil return when the oil level in the suction header rises. The compressor suction lines must always enter the suction header on the topside. A recommended suction header design is shown below.
Suction gas
Suction gas to
compressor
10 FRCC.PC.032.A4.02
Application Guidelines
System design recommendations
Oil level regulator
To ensure ideal pressure equalization, the suction header must be symmetrical and the lines from the suction header to each compressor must be short and identical. These recommendations are not so critical when using an active system.
Danfoss recommends the following as necessary for secure a suction header installation:
• The suction header should be adequately sized
Oil level regulator monitors the oil level and controls oil injection by switching the solenoid valve on and o to maintain an acceptable oil level in the compressor the crankcase. When crankcase oil level cannot be restored within a period of time (setting value), the alarm contactor will be activated and stop the compressor to protect it from damage (some oil level regulator do not have an alarm function).
According to the function, there are three types of oil level regulator: electronic, electromechanical and mechanical. For a high-pressure oil reservoir system, Danfoss recommends individual electronic oil control regulators over the mechanical oat ball oil regulator system for eective oil regulation. For the a low-pressure system, all types are allowed.
Danfoss has qualied the below oil level regulators. Due to various operations in refrigeration systems, the customer needs to verify the conguration specied for their own solutions.
for equal distribution of returning refrigerant gas and oil to each individual compressor; also the suction header should be installed horizontally.
• The gas velocity in the suction header must be a maximum of 4 m/s.
• The suction line and the suction header must be insulated to limit suction gas superheat.
• TEKLAB: TK3-DANF-R01: Danfoss recommends this kind of Oil level regulator for its overall quality. It can judge the oil level precisely even when there is some oil foaming. The total time before the alarm is four minutes with the new control module, which is suitable for LLZ compressors. The adaptor of TEKLAB perfectly matches the oil sight glass tting of LLZ compressor. A lter is needed before Oil level regulator.
• Henry AC&R: OP-02: The action and control logic works well with LLZ compressors, while adaptors can t, but not very well, with the oil sight glass tting. A lter is needed before oil level regulator.
Note: Customers must refer to the manufacturer's guidelines on oil level regulators for proper set­up and operation.
11FRCC.PC.032.A4.02
Application Guidelines
Oil separator / oil reservoir
System design recommendations
Oil separator for passive system
The role of the oil separator is to intercept the mixed oil from the compressed refrigerant gas and returns it back to the compressor to assure ecient lubrication of its moving parts, and also to improve the system heat exchangers’ eciency. In our manifolding system, the oil separator is installed in the compressor discharge line as shown below.
Passive system
Non return valve
Oil equalization
line
Compressor 1 Compressor 2
Suction header
No oil separator category is included in this guidelines. For more details, please refer to the manufacture’s guidelines.
Regarding passive solutions, it is recommended to use an oil separator with a oating-ball valve. The oating-ball valve can control the oil ow and act as a capillary in the oil return line; therefore, there is no need to install an oil capillary in the system.
To condenser
Non return valve
Oil separator with oating-ball valve
Oil lter
Oil separator / Oil reservoir for active system
From evaporator
When an active system is adopted by the customer, the oil separator is always considered together with oil reservoir.
Active system
Suction header
Non return valve
Compressor 1
Oil level regulator Oil level regulator Oil level regulator Oil level regulator
Non return valve
Compressor 2 Compressor 3 Compressor 4
Due to system design, loads and defrost cycles, etc, there will be varying amounts of oil returning to the oil separator. Because of this, a safety reserve of oil is required for successful operation of the active system.
High pressure
Low pressure
Non return valve
Non return valve
Oil lter
Non return valve
Combined oil separator/reservoir
12 FRCC.PC.032.A4.02
Application Guidelines
System design recommendations
High pressure oil reservoir (combined oil separator/oil reservoir)
Danfoss recommends that high-pressure systems are congured in active solutions. These systems store the oil in a common oil separator / reservoir at compressor discharge pressure (see the gure below). The advantage is that these systems do not need a separated oil reservoir but make use of a combined oil separator / reservoir arrangement ,which normally results in a cost saving over traditional low-pressure systems.
Common suction header
From an application point of view, high-pressure systems are more critical than traditional low pressure systems and care must be taken to make sure that the separator / reservoir installed is of sucient size and oil content (as per manufacturer’s recommendation) so that there is always oil stored. And pay special attention to avoid discharge gas entering the compressor oil sump, which could lead to some negative eects such as higher discharge and oil temperatures, less lubrication capability and the loss of eciency due to hot-gas bypass.
To condenser
From evaporator
Oil separator/Oil reservoir
Active solution with high pressure oil reservoir (combined oil separator/oil reservoir)
Low pressure oil reservoir with separate oil separator
valve). Therefore, the amount of refrigerant dissolved in the oil will be limited. The pressure
drop is low when the oil enters the compressor Usage of an oil reservoir is very common in low­pressure systems to control the variations in oil quantity during operation (see below). In this conguration, the oil reservoir is maintained at a pressure slightly above the compressor suction
and the amount of ash gas formed in the sump
is small. The dierential pressure required for
sucient oil ow from the oil reservoir to the
compressor is system specic, depending upon
the application and components chosen. pressure using a dierential pressure valve (check
Common suction header
Oil filter
To condenser
From evaporator
Oil separator with float ball valve
Diffe rential pressu re Check valve
Oil reservoir
Active solution with low pressure oil reservoir
Oil filter
13FRCC.PC.032.A4.02
Compressor 1
Compressor 2
Application Guidelines
System design recommendations
In brief, oil separator and oil reservoir are always considered together regarding active system.
For active solution with high pressure oil reservoir system it is recommended to use oil separator(no oat ball valve) with oil stored function. In
it is recommended to work together with oil separator which with oat ball valve.
Generally Danfoss recommend to use high pressure oil reservoir system (one oil seperator
with oil reserve function). other words, a combined oil separator/oil reservoir. For low pressure oil reservoir system,
Danfoss has qualied the below oil separator. Due to various applications in refrigeration systems, the customer needs to verify the
conguration specied for their own solutions.
Please refer to oil separator's guideline for more
information.
Passive solution
Country* CN NAM/CN NAM/CN EMA EMA EMA
Company Fasike O&F Emerson ALCO Henry AC&R Frigomec Frigomec Carly Model F-65 A-WE S-CE SO/ERS SO/ER Turboil-F for PVE oil Typ e Filter Impingement Impingement Filter Filter-demister Centrifugal
Note*: The countries listed here only indicate whether the product is available in local country or not for now. Regardless the availability, all the OS above has been qualied by Danfoss under certain conguration.
Active solution
Country* CN EMA EMA
Company Fasike O&F Frigomec Carly
Model F-66Q SRO/ERS Turboil-R for PVE oil
Typ e Centrifugal Oil-stored Filter Oil-stored Centrifugal Oil-stored
Note*: The countries listed here only indicate whether the product is available in local country or not for now. Regardless the availa­bility, all the OS above has been qualied by Danfoss under certain conguration.
Economizer for parallel vapour injection compressors
Refrigerant charge limits
A single economiser (heat exchanger) can be applied in a parallel economiser conguration. A system may use one economizer with a single circuit on the liquid line and multiple circuits
From condenser / liquid receiver
Drier lter
Expansion valve
Heat exchanger
Solenoid valve
To evaporator
on the vapour side. In the case of refrigerant being fed into the injection port of a stationary compressor, a non return valve should always be tted.
From condenser / liquid receiver
Filter
Solenoid valve
Cap tube
Heat exchanger
To evaporator
Compressor 1 Compressor 2
If refrigerant charge exceeds the limit, a liquid receiver and suction accumulator will be essential to ensure that the system runs reliably.
Compressor models
Tandem
Trio
Quadro
LLZ013- 015 -018 5.9
LLZ024 9.4
LLZ013- 015 -018 7.7
LLZ024 12. 3
LLZ013- 015 -018 10.0
LLZ024 16.0
Refrigerant charge
limit(kg)
14 FRCC.PC.032.A4.02
Application Guidelines
Installation and service
Piping design
Wiring and rotation direction
Failure analysis
Due to the various LLZ parallel congurations, Danfoss only provides an even tandem piping design. For uneven, trio and quadro active systems, the customer can make their own design based on the velocity limits.
For each tandem conguration specic outline drawings are available as indicated on the following pages. These drawings must always be followed.
All compressors in a tandem unit must be electrically wired individually.
When one compressor in a parallel system fails, the chance of foreign particles entering other compressors is greatly increased. Therefore a
No changes shall be made to the indicated tubing diameter and tting types. As for passive systems, the oil equalisation line shall be made of copper tube and assembled in such a way so that it does not extend above the connection height and must be horizontal so as not to trap oil.
Please contact Danfoss Sales for specic drawings.
Compressors should run with the correct rotation direction. This can be achieved by having the correct phase sequence on each compressor motor terminal (L1-T1, L2-T2, L3-T3).
failure analysis must be done quickly to ensure further proper running conditions for the overall installation (i.e.: oil analysis).
15FRCC.PC.032.A4.02
Application Guidelines
Sound and vibration management
Running sound level
Average sound levels below is at ARI LBP condition
50Hz 60Hz
Model
LLZ013 tandem 80 72 82 74 LLZ015 tandem 82 74 85 77 LLZ018 tandem 85 75 86 76
LLZ024 tandem 87 77 88 78
Sound power(dBA)
Without jacket
Sound power(dBA)
With jacket
Sound power(dBA)
Without jacket
Sound power(dBA)
With jacket
16 FRCC.PC.032.A4.02
Application Guidelines
Ordering information
To build a complete tandem, one must order two compressors and the tandem kit. Danfoss LLZ compressors can be ordered in either industrial packs or in single packs. Please refer to the single
Kit code number 120Z5073
Designation Qty
1 Flat washer 8 2 Spacer 8 3 Rotolock sleeve 2 4 Rotolock nut 2 5 Adaptor 2 6 O-ring 2 7 Teon seal 2
compressor application guidelines for ordering. All LLZ tandem conguration will share the same tandem kit.
17FRCC.PC.032.A4.02
Application Guidelines
Parallel units LLZ013-15-18-24
Composition of LLZ013­024 uneven tandem/trio/ quadro
Composition of LLZ013­024 even tandem
Active system
These compositions can only work with active systems.
Danfoss will not provide drawings for these congurations. Pipe sizes can be calculated based
on the velocity the limits in “Essential piping design" section. And Customers need to do their own validation.
A
Active system (50 Hz)
Tandem model A B C
LLZ013- 018 1/2 " 3/4" 1"1/8
LLZ024 3/4" 1"1/8 1"3/8
For more details, please refer to drawing 0ZZ0218B(50Hz). Note: the dimensions are external diameters
B
C
18 FRCC.PC.032.A4.02
Application Guidelines
Passive system
Parallel units LLZ013-15-18-24
E
D
A
C
B
Passive system (50 Hz)
Tandem model A B C D E
LLZ013- 018 1/2" Ø64.00 1"1/8 3/4" 1/2"
LLZ024 1/2" Ø79.38 1"3/8 1"1/8 3/4"
For more details, please refer to drawing 0ZZ0217B(50Hz). Note: the dimensions are external diameters
Compressor mounting The tandem is xed on the frame using the
exible grommets supplied with the compressor.
The compressors are xed on the rails (not supplied) using at washers rigid spacer included in the “tandem kit” reference 120Z5073 (to be ordered with the compressors). An additional rigid spacer (mounting kit for single compressors) must be placed under the rail grommets (see below drawing).
Tightening torque 15Nm
Tightening torque 15Nm
19FRCC.PC.032.A4.02
Application Guidelines
Parallel units LLZ013-15-18-24
Suction and discharge connection
Both suction and discharge line go through a rotolock connection. Pipes are brazed to the sleeve ‘ and xed to the compressor with nuts ’.
Note: sleeve ‘ and nut ’ are the supplied with LLZ single service kit (120Z5067-LLZ013/015/018 and 120Z5068-LLZ024).
’
’
Suction line Discharge line
’
’
Oil equalisation connection
As for passive systems, an oil equalisation line is brazed to the sleeve .
A rotolock nut xes the sleeve and adaptor , which is connected with oil sight glass port . The O-ring and Teon ring  guarantee the
seal.
20 FRCC.PC.032.A4.02
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Secop Compressors for Danfoss
Our products can be found in a variety of applications such as rooftops, chillers, residential air conditioners, heatpumps, coldrooms, supermarkets, milk tank cooling and industrial cooling processes.
http://cc.danfoss.com
Danfoss Commercial Compressors, BP 331, 01603 Trévoux Cedex, France | +334 74 00 28 29
FRCC.PC.032.A4.02 - January 2015 - Replaces FRCC.PC.032.A3.02 - April 2014 © Copyright Danfoss | Commercial Compressors | 2015.01
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