marine reefer compressor

1. PURPOSE ON SHIPS

• Maintains low temperature in provision rooms (meat, dairy, vegetables, etc.)
• Preserves food during long voyages
• Sometimes used in cargo cooling (reefer ships)

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 2. TYPES OF COMPRESSORS USED ON SHIPS

1.  Reciprocating Compressor (Most Common)

2.  Rotary Screw Compressor

3.  Scroll Compressor (rare on ships)

4.  Centrifugal Compressor (for large industrial plants)

Most common on merchant ships:
🔧 Semi-hermetic reciprocating compressors (e.g., Sabroe, Bitzer, Bock)

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 3. WORKING PRINCIPLE

The compressor is the heart of the refrigeration cycle:

Cycle Stages:

1.  Low-pressure vapor enters compressor

2.  Compressor compresses vapor to high-pressure, high-temp

3.  Hot gas goes to condenser → cooled and becomes liquid

4.  Liquid passes expansion valve → pressure drops

5.  Low-pressure liquid enters evaporator → absorbs heat → becomes vapor

6.  Vapor returns to compressor

 

5.  MAIN COMPONENTS

 

Component	Function
Compressor	Compresses refrigerant gas
Condenser	Cools and condenses hot gas
Expansion Valve	Controls refrigerant flow & drops pressure
Evaporator	Absorbs heat from provision rooms
Receiver	Stores liquid refrigerant
Oil Separator	Removes oil from refrigerant
Solenoid Valve	Stops flow during compressor off cycle
Pressure Gauges	Monitors suction & discharge pressure
Thermostat	Maintains room temperature

 

6.  COMMON REFRIGERANTS USED

 

 

Refrigerant	Type
R-134a	Common, safe
R-404A	Low-temp
R-407C	Eco-friendly
NH₃ (Ammonia)	Industrial use, toxic

 

 

6. OPERATION CHECKS (Daily Watch)

• ✅ Check oil level & pressure
• ✅ Monitor suction & discharge pressure
• ✅ Observe sight glass (bubbles = shortage)
• ✅ Listen for abnormal noise/vibration
• ✅ Check for frosting on suction line
• ✅ Drain condensate from evaporator

 

7.  TROUBLESHOOTING GUIDE

 

Problem	Causes	Action
🔺 High Discharge Pressure	Dirty condenser, overcharge	Clean condenser, check refrigerant
🔻 Low Suction Pressure	Refrigerant leak, clogged filter	Leak test, refill refrigerant, clean filter
⚠️ Compressor Not Starting	No power, trip, thermostat off	Check fuses, control panel, reset
❄️ Ice on Evaporator	Expansion valve stuck, low airflow	Check valve and fan operation
🧯 Low Oil Pressure	Oil filter clogged, pump failure	Change filter, check oil pump

 

 

 

8.  MAINTENANCE SCHEDULE

Frequency	Task
Daily	Check oil, pressures, leaks, temperature
Weekly	Drain condensate, check safety cutouts
Monthly	Clean condenser, check belt tension
Quarterly	Test all valves, inspect insulation
Yearly	Overhaul compressor, change oil & filters

 

 

9. SAFETY DEVICES

• HP/LP cut-outs – trip compressor if pressure exceeds limits
• Thermal overload relay – protects motor
• Oil pressure cut-out – trips if oil pressure is low
• Solenoid valve – stops refrigerant flow during off cycle

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 10. SHIPBOARD MAKES & MODELS

• Sabroe (Sabroe CMO, Sabroe SMC)
• Bitzer (Open/semi-hermetic)
• Bock
• Carrier
• Daikin
• Grasso (in larger systems)

SOLAS Regulations for Refrigeration Compressor Systems on Ships

While SOLAS does not directly mention "reefer compressors" by name, it does regulate systems that involve machinery, refrigeration, fire protection, safety, and cargo. These rules ensure safe operation of the provision refrigeration plant, especially in case of fire, gas leaks, electrical faults, etc.

 

 

 

 

 

Relevant SOLAS Chapters for Reefer Compressors

 

SOLAS Chapter	Applies To	Importance for Reefer Compressor
II-1	Construction – Machinery	Safety of compressors, motors, cooling systems
II-2	Fire Protection	Fire detection, fixed gas suppression, flammable refrigerants
III	Life-Saving Appliances	Safety in case of gas leak or fire near accommodation
V	Safety of Navigation	Reefer alarms monitored in bridge (if connected)
VII	Carriage of Dangerous Goods	Applies when carrying cargo reefer containers (with refrigerants)
XII	Bulk Carrier Safety	If reefer system part of cargo operations
XI-2	ISPS Code	Safety access to machinery spaces (including refrigeration rooms)

 

KEY SAFETY REQUIREMENTS UNDER SOLAS FOR REEFER SYSTEMS

1.  Fire Safety (SOLAS Chapter II-2)

• Fire detection system in reefer machinery room
• Fixed firefighting system (CO₂ or dry powder) required if compressor uses flammable refrigerant (e.g., R290 – propane, NH₃ – ammonia)
• Reefer rooms must be fire insulated if near accommodation

2. Ventilation

• Mechanical ventilation required in reefer compressor rooms
• If refrigerant is toxic (like ammonia) → emergency exhaust fan with alarm system is mandatory

3.  Gas Detection System

• Must be installed for systems using toxic or flammable refrigerants
• Alarm must sound if gas level exceeds threshold
• Alarm must be audible on bridge and engine control room

4.  Pressure Relief Devices

• Compressors and receivers must have pressure relief valves
• Vent lines from relief valves should go to safe open air (outside accommodation)

5.  Shutdown & Isolation

• Emergency stop for compressors required outside reefer room
• Manual shut-off valves to isolate sections in case of leak

6.  Oil & Refrigerant Handling

• Proper storage and handling procedures required under SOLAS and MARPOL
• Maintenance logs and MSDS (Material Safety Data Sheet) must be available

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 Required Certificates & Documents

1.  Refrigeration Plant Manual (as per Class & Flag)

2.  MSDS for refrigerants

3.  Safety Data Sheet for compressor oil

4.  Test records of pressure relief valves

5.  Annual inspection records (Class & Port State may check)

Summary: What SOLAS Demands for Reefer Compressor Area

✅ Fire detection
✅ Fixed firefighting system (if flammable/toxic gas)
✅ Proper ventilation
✅ Emergency stop
✅ Gas leak alarm system
✅ Pressure relief valves
✅ Safe refrigerant/oil storage
✅ Documents & MSDS sheets

 

 

1: What will you do if refrigerant gas leaks in the reefer room?

✅ Answer:

·        First, raise the alarm and inform the bridge and duty officer.

·        Do not enter the room without proper PPE and breathing apparatus — refrigerants can displace oxygen or be toxic.

·        Isolate the compressor and valves from outside using the emergency stop and manual shut-off valves.

·        Start mechanical exhaust ventilation to remove leaked gas.

·        Check the gas leak detection system and locate the leak using soapy water or leak detector.

·        If necessary, evacuate personnel from nearby areas.

·        Once safe, carry out repairs as per company procedures and recharge refrigerant.

·        Log the incident and inform class/flag if required.

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 Q2: How will you act if the CO₂ system activates in the reefer room?

✅ Answer:

·        Immediately raise the alarm and do not enter the space — CO₂ is lethal in enclosed areas.

·        Ensure all crew are evacuated from the reefer room.

·        Confirm remote CO₂ release has completed and the room is sealed.

·        Inform the Chief Engineer, Bridge, and Safety Officer.

·        After activation, wait until CO₂ is fully vented and atmosphere tested as safe using a gas detector (O₂ meter).

·        Only then enter with permission and proper gear.

·        Investigate the cause of fire or false activation, and carry out repairs.

·        Reinstate the CO₂ system and ensure room is operational again.

·        Log and report to class/flag if required.

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Q3: What are the SOLAS requirements for fire protection in reefer rooms?

✅ Answer:

·        As per SOLAS Chapter II-2, reefer rooms must have:

o   Fire detection system (smoke or heat detectors)

o   Fixed fire extinguishing system, like CO₂, especially if refrigerant is flammable or toxic (e.g., ammonia, propane)

o   Emergency stop switches located outside the reefer room

o   Ventilation system to remove leaked gas or smoke

o   Gas detection system for toxic/flammable refrigerants

o   Pressure relief valves in compressor and receivers

·        Fire insulation must be provided if reefer room is near accommodation or escape routes.