What to check on a Refrigerator / Freezer.
A provision refrigerator or freezer is a self-contained vapour-compression cooling box built into the ship's provision store, distinct from a reefer container or an air-conditioning plant in that it runs a sealed refrigerant circuit against a fixed insulated room rather than a cargo box or an air duct system. It holds two temperature bands separately: chill rooms around +2 to +8 degrees C for fresh produce, dairy and meat awaiting use, and freeze rooms at -18 to -20 degrees C for long-term stores. The compressor runs near-continuously in tropical trades…
What defines this type
A provision refrigerator or freezer is a self-contained vapour-compression cooling box built into the ship's provision store, distinct from a reefer container or an air-conditioning plant in that it runs a sealed refrigerant circuit against a fixed insulated room rather than a cargo box or an air duct system. It holds two temperature bands separately: chill rooms around +2 to +8 degrees C for fresh produce, dairy and meat awaiting use, and freeze rooms at -18 to -20 degrees C for long-term stores. The compressor runs near-continuously in tropical trades, cycling on thermostat or pressure control rather than the short intermittent runs typical of a domestic fridge.
Main components
Compressor
Usually a semi-hermetic reciprocating or scroll compressor mounted in the compressor room, sized for the worst-case ambient the vessel will trade in, not the average. Semi-hermetic units allow valve plate and piston service without removing the whole machine.
Condenser
Air-cooled or seawater-cooled shell-and-tube condenser that rejects heat picked up in the evaporator plus the compressor's work of compression. Air-cooled units are simpler but foul quickly with salt air; seawater-cooled units need a dedicated cooling water pump and strainer.
Evaporator and expansion device
Finned-coil evaporators inside the chill and freeze rooms, fed by a thermostatic expansion valve or, on smaller plants, a fixed capillary tube. A defrost heater or hot-gas defrost line clears ice buildup on a timer or demand cycle.
Room structure
Insulated sandwich panels, typically polyurethane core, with a vapour barrier to stop moisture migration into the insulation, plus heated door frames on freezer doors to stop gasket icing.
Selection and sizing
Sizing is driven by store room volume, design ambient temperature, door opening frequency and crew number, not by a generic capacity chart. Key figures a buyer checks:
- Room volume in cubic metres against expected provisioning interval between ports
- Refrigerant type, now typically R404A being phased down, R452A or R290 on newer installations
- Compressor duty cycle rating for continuous tropical ambient, not intermittent domestic duty
- Number and size of doors, since each opening is a heat load event
- Insulation panel thickness against the target temperature band
Regulations and class
The Maritime Labour Convention 2006 requires separate, adequately sized chill and freeze provision stores for the crew complement, which sets the baseline the plant is sized against. Refrigerant choice is constrained by the Montreal Protocol and its Kigali Amendment phasing down high-GWP HFCs, so replacement refrigerant availability is a real operating concern over a ship's life. Class societies survey the provision refrigeration plant on the same periodic survey cycle as other auxiliary machinery, checking pressure vessel condition, safety valve function and refrigerant containment; there is no cargo-refrigeration-style continuous survey requirement for provision plants.
Typical faults
| Fault | Cause | Consequence |
|---|---|---|
| Slow loss of cooling capacity | Refrigerant leak at a flare joint or shaft seal | Room temperature creeps up unnoticed until stores spoil |
| High head pressure trip | Condenser fouled with salt deposit or airflow blocked | Compressor cuts out repeatedly, room warms during each stop |
| Iced-over evaporator coil | Failed defrost heater or timer | Airflow blocked, room temperature rises despite compressor running |
| Door gasket perished | Age, or freezer door heater failure | Frost buildup around the frame and higher energy use to hold temperature |
What to look for in a supplier
- Refrigerant compatible with current and near-future Montreal Protocol schedules
- Semi-hermetic or fully serviceable compressor rather than a sealed domestic-grade unit
- Panel and door hardware rated for marine salt exposure, not shore cold-store hardware
- Spare parts and refrigerant availability through a network the vessel's trading pattern actually reaches
- Documented capacity calculation for the specific room volume and ambient design condition
A provision plant that trips on high head pressure in port and runs fine at sea is telling you the condenser is fouled, not that the compressor is failing, so clean it before condemning parts.