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© Danfoss | Climate Solutions | 2023.06

6.9  Avoiding slugging

To prevent slugging:

  The complete refrigeration plant must be properly designed.
  All components must be compatibly rated with each other with regard to output (particularly the 

evaporator and expansion valves).

  Suction gas superheating at the compressor input 

should be > 15 K

 (check the setting of the 

expansion valve).

  Regard oil temperature and pressure gas temperature. (The pressure gas temperature has to be 

high enough min. 122°F (50 °C), so the oil temperature is > 86°F (30 °C) ).

  The system must reach a state of equilibrium. 
   Particularly in critical systems (e.g. several evaporator points), measures such as the use of liquid 

traps, solenoid valve in the liquid line, etc. are recommended. 

 

There should be no movement of refrigerant in the compressor while the system is at a 
 standstill.

Slugging can result in damage to the compressor and cause 
refrigerant to leak.

6.10  Filter dryer

Gaseous CO

2

 has a significantly lower solubility in water than other refrigerants. At low temperatures 

it can therefore cause blocking of valves and filters due to ice or hydrate. For this reason we recom-
mend the use of an adequately sized filter drier and a sight glass with a moisture indicator.

7.1 Preparation

Before starting any work on the compressor:

  Switch off the compressor and secure it to prevent a restart.
  Relieve compressor of system pressure.

  Prevent air from infiltrating the system!

After maintenance has been performed:

  Connect safety switch.
  Evacuate compressor.
  Release switch-on lock.

The decompression has to be carried out in a way that no dry ice 
respectively solid CO

2

 is produced which blocks the outlet and 

could hinder the streaming out of CO

2

. Otherwise, there is the 

danger that pressure can be built up again.

6

|

 Commissioning

7

|

 Maintenance

Summary of Contents for BOCK UL-HGX12e CO2 LT

Page 1: ...e Reciprocating Compressor BOCK UL HGX12e CO2 LT UL HGX12e 20 ML 0 7 CO2 LT UL HGX12e 20 S 1 CO2 LT UL HGX12e 30 ML 1 CO2 LT UL HGX12e 30 S 2 CO2 LT UL HGX12e 40 ML 2 CO2 LT UL HGX12e 40 S 3 CO2 LT Tr...

Page 2: ...product safety labels Refer to local building codes for installation requirements CO2 applications require a completely new kind of system and control They are not a general solution for the substitut...

Page 3: ...16 5 3 Circuit diagram for direct start 280 V 460 V Y 18 5 4 Electronic trigger unit INT69 G 20 5 5 Connection of the electronic trigger unit INT69 G 20 5 6 Functional test of the electronic trigger u...

Page 4: ...g compressors are pressurized machines and therefore require particular caution and care in handling The maximum permissible overpressure must not be exceeded even for testing purposes Danger of suffo...

Page 5: ...cted and approved in accordance with legal regulations The compressors are intended for use with CO2 in transcritical and or subcritical systems in compli ance with the limits of application Only the...

Page 6: ...kept on a relatively low temperature level specially during high load Oil pump independent of direction of rotation for reliable and safe oil supply One decompression valve each on the low and high pr...

Page 7: ...change the IP protection class 2 2 Name plate example 2 Product description 1 2 3 4 5 13 12 7 11 6 10 8 9 SE 55 27 3 32 8 UL HGX12e 40 S 3 CO2 LT 10 7 6 2A 111A 64A BC12345A001 Bock GmbH Benzstr 7 726...

Page 8: ...f the sight glass damage to the compressor is possible if overfilled or underfilled Fig 4 max min 21 fl oz 0 6 Ltr Oil level 3 Areas of application 3 1 Refrigerants R744 CO2 required CO2 quality 4 5 5...

Page 9: ...140 F 20 C 60 C Max permissible discharge end temperature 320 F 160 C Min discharge end temperature 122 F 50 C Min oil temperature 86 F 30 C Max permissible switching frequency 12x h A minimum runnin...

Page 10: ...1 Storage and transportation Use transport eyelet Do not lift manually Use lifting gear Storage at 22 F 158 F 30 C 70 C maximum permissible relative humidity 10 95 no condensation Do not store in a co...

Page 11: ...from the valve for soldering and accordingly cool the valve body during and after soldering Only solder using inert gas to inhibit oxidation products scale 4 Compressor assembly B1 A1 4 5 Flange shut...

Page 12: ...es can cause cracks and tears which can result in a loss of refrigerant Proper layout of the suction and pressure lines directly after the compressor is integral to the smooth running and vibration be...

Page 13: ...peration Pipe connection Pipe connection Fig 11 Opening the shut off valve Spindle turn to the left counter clockwise as far as it will go Shut off valve completely opened service connection closed Fi...

Page 14: ...ion is already available from the factory for the purpose of installing the additional oil level monitoring component Oil should be returned from the oil separator to the compressor via the D1 connect...

Page 15: ...ttaching accessories with an electrical cable a minimum bending radius of 3x the cable diameter must be maintained for laying the cable 5 Electrical connection 5 1 Information for contactor and motor...

Page 16: ...50435606290en US0201 Danfoss Climate Solutions 2023 06 5 Electrical connection Designation on the name plate Y 5 2 Connection of the driving motor The compressor is designed with a motor for star delt...

Page 17: ...re Spannung Low voltage Bas voltage Y Hohe Spannung High voltage Haut voltage L3 L1 L2 L3 L1 L2 ical connection rdement lectrique Y 96027 11 06 DGbF Niedere Spannung Low voltage Bas voltage Y Hohe Spa...

Page 18: ...7 6 5 4 3 2 1 FC1 1 I I I 1 2 QA2 3 4 5 6 EC1 3 M 5 3 Circuit diagramm for direct start 280 V 460 V Y Fig 13 Compressor terminal box BP1 High pressure safety monitor BP2 Safety chain high low pressure...

Page 19: ...450435606290en US0201 19 BP1 P QA2 BP2 P L1 1 L2 1 L3 1 L1 2 N PE BT3 BT2 BT2 EB1 FC1 1 Motor protection switch FC2 Control power circuit fuse INT69 G Electronic trigger unit INT69 G QA1 Main switch Q...

Page 20: ...remedy the cause The relay switching output is executed as a floating changeover contact This electrical circuit operates according to the quiescent current principle i e the relay drops into a the id...

Page 21: ...oil sump heater must generally be connected and operated 5 8 Selection and operation of compressors with frequency converters For safe operation of the compressor the frequency converter must be able...

Page 22: ...Pressure strength test The compressor has been tested in the factory for pressure integrity If however the entire system is to be subjected to a pressure integrity test this should be carried out in...

Page 23: ...system To eliminate the possibility of dry ice formation when the system is operating during and after the filling process the shut off point of the low pressure switch should be set to a value of at...

Page 24: ...f oil liquid shocks reduced capacity of the refrigerating system Ensure that both shut off valves are open before starting the compressor If larger quantities of oil have to be topped up there is a ri...

Page 25: ...ivates repeatedly check valve and replace if necessary as during blow off extreme condi tions can occure which may result in a permanent leak Always check system for refrigerant loss after activation...

Page 26: ...e compressor while the system is at a standstill Slugging can result in damage to the compressor and cause refrigerant to leak 6 10 Filter dryer Gaseous CO2 has a significantly lower solubility in wat...

Page 27: ...ronment It is essential to ensure good ventilation or conduct the CO2 into the outdoors to avoid danger of suffocation When releasing CO2 avoid a fast drop in pressure to prevent oil from exiting with...

Page 28: ...r locked permissible frequency range Discharge line DV Suction line SV 50 60 Hz Y Y cfh V A kW HP A Hz lb mm inch mm inch Ltr fl oz Ltr fl oz 20 ML 0 7 CO 2 LT 2 61 73 265 290 V 440 480 V Y 3 60 Hz 4...

Page 29: ...current on request The specifications for max power consumption apply for 60 Hz operation Take account of the max operating current max power consumption for design of fuses supply lines and safety de...

Page 30: ...Schweissanschl Transkritische Ausf hrung transcritical version Subkritische Ausf hrung subcritical version Typ type Teile Nr part no Typ type Teile Nr part no Typ type Teile Nr part no Typ type Teile...

Page 31: ...e lockable 7 16 UNF D1 Connection oil return from oil separator 1 4 NPTF E Connection oil pressure gauge 1 8 NPTF F Oil drain M12x1 5 I Connection hot gas temperature sensor 1 8 NPTF J Connection Oil...

Page 32: ...K X 20 120 K N TK FK X 50 980 K N TK Serial number BC00000A001 BN99999Z999 complies with the following provisions of the above mentioned Directive According to Annex I points 1 1 2 1 1 3 1 1 5 1 3 2 1...

Page 33: ...20 120 K N TK FK X 50 980 K N TK Serial number BC00000A001 BN99999Z999 complies with the following provisions of the above mentioned Statutory instrument According to Schedule 2 part1 points 1 1 2 1...

Page 34: ...anfoss Climate Solutions 2023 06 11 UL Certificate of Compliance Dear customer the Certificate of Compliance can be downloaded by the following QR Code https vap bock de stationaryapplication Data Doc...

Page 35: ...D US Danfoss Climate Solutions 2023 06 AQ450435606290en US0201 35...

Page 36: ...D US 36 AQ450435606290en US0201 Danfoss Climate Solutions 2023 06...

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