Operational guide · Safety & equipment

Refrigeration Plant

The refrigeration plant transfers heat from cold rooms to the cooling medium. Understanding the cycle, circulation and controls helps readers interpret temperatures and alarms, distinguish faults and connect maintenance with refrigerant management.

refrigerationHFCKigali AmendmentF-gas

Operational Explanation

A vapour-compression circuit maintains the required cold-room temperature by removing heat; a running compressor alone does not demonstrate effective service. In the basic cycle:

Component	Function in the cycle
Evaporator	Low-pressure refrigerant absorbs heat from air or a secondary fluid and evaporates.
Compressor	Draws in vapour and compresses it, increasing pressure and temperature.
Condenser	Rejects heat to cooling air or water; the vapour condenses into high-pressure liquid.
Expansion device	Reduces pressure and controls the evaporator feed; refrigerant returns to the low-pressure side.

The refrigerant circuit and air or water circulation perform different tasks. Inadequate flow or a dirty heat exchanger can reduce heat transfer even while the compressor runs. Controls, fans, defrost and drainage contribute to cold-room performance. Identify these paths and any secondary circuits on the ship’s diagram. Danfoss — refrigeration cycle principles.

Regulatory Reference

MARPOL VI/12: ODS; Regulation (EU) 2024/573: fluorinated gases; ISM Code §10: maintenance. These are distinct regimes: identify the substance, equipment and activity before selecting the rule and record.

CFCs and HCFCs are ozone-depleting substances; HFCs are not, although they may have high global warming potential (GWP). Kigali addresses the reduction of HFC production and consumption: it does not make an HFC subject to the MARPOL ODS record book. UNEP Ozone Secretariat — Kigali and HFCs.

Refrigeration units of intermodal containers, including reefers, are a specific mobile category under Article 5(3)(b). Paragraph 5 defers application of paragraphs 1 and 6 to their operators until 12 March 2027: check thresholds and exemptions, without bringing that deadline forward or confusing it with general Article 4 duties. Regulation (EU) 2024/573, Article 5.

Where the EU Regulation applies, Article 13(3) prohibits using gases with GWP ≥2500 for maintenance or servicing of refrigeration equipment from 1 January 2025. It does not by itself order shutdown of equipment retaining its existing charge. Military equipment and applications below −50 °C are excluded, alongside any authorised exemptions. Until 1 January 2030, derogations remain for reclaimed Annex I gases with the required label, or recycled gases recovered from such equipment and used by the undertaking that recovered them or for which recovery was performed. Check origin and conditions; air-conditioning and heat pumps have the separate Article 13(4). Regulation (EU) 2024/573, Article 13(3)–(4).

MARPOL VI/12 separately governs ozone-depleting substances (ODS). The HCFC installation ban covers ships constructed from 1 January 2020 and, on earlier ships, equipment contractually delivered from that date (or actually delivered where no contractual date exists). Ships subject to VI/6.1 need an ODS equipment list and, where they have rechargeable ODS systems, an ODS record book: check the voyage criterion in regulation 6.1 as well as tonnage. Regulation 12 excludes permanently sealed equipment without charging connections or potentially removable ODS-containing components. IMO — MARPOL VI/12 and VI/6.1.

For operation and maintenance, ISM 10.1–10.4 connects applicable requirements, inspections at appropriate intervals, defects and the possible cause if known, corrective action and records. Intervals, pressure limits, compatible refrigerant and oil depend on the plant and relevant instructions; this page does not set universal values. IMO — ISM Code §10.

Scope of Application

This page supports familiarisation with shipboard refrigeration, particularly provision plants. Many systems share the basic cycle, but direct or indirect circuits, air- or water-cooled condensation, refrigerant and controls change the checks and risks. A reefer is a container unit with its own cargo management and responsibilities; it is distinct from the ship’s cold-room plant.

For EU duties, check jurisdiction, operator, equipment and activity: EU flag alone does not decide every case. Recital 14 and Article 4 distinguish emission prevention and repair without undue delay from periodic checks, records and certification linked to the categories and activities in Articles 5, 7 and 10. Being fixed to the ship does not automatically make a plant “stationary” for EU purposes; reefers have their own mobile category. Regulation (EU) 2024/573, Articles 3–5, 7 and 10.

Refrigerant work, leakage and conversions require manufacturer instructions, the safety data sheet and competent personnel. Lower GWP does not demonstrate compatibility or absence of risk: pressure, toxicity and flammability depend on the substance and design. This page provides no charging, recovery, adjustment or leak-response procedure.

Procedure / How to Complete It

Familiarisation pathway. Use the ship’s diagram and manual to understand operation and records; appointed personnel perform interventions.

Identify the service. Find the rooms served, required temperatures, sensors, alarms, compressors and standby units; distinguish measured temperature, setpoint and stored product.
Follow the cycle and flows. Locate the four components, high/low-pressure sides and air/water circulation. Recognise defrost, drainage and conditions that increase load, such as door openings or new provisions.
Read performance. Compare temperature trends, running time, alarms and data required by the manual. Pressures, superheat and subcooling, where relevant, must be interpreted with the refrigerant and conditions, rather than a number valid for every plant.
Describe an abnormality. Report symptoms and the impact on service; assess air/water flow, heat exchangers, controls and the refrigerant circuit through the procedure. High temperature alone does not identify a leak. Do not turn an alarm into repeated resets or a diagnosis into a top-up.
Connect maintenance and refrigerant. Record the equipment, work, outcome and defects in the onboard system. For additions, recovery or delivery ashore, identify the substance and actual quantities; use ODS or F-gas records when required by the corresponding regime, alongside SMS/PMS records.
Verify the result. After work, competent personnel verify performance and safety under the prescribed method. Retain remaining limitations, follow-up and repair verification: restarting a compressor or adding charge alone does not close a defect.

Danfoss — interpreting cold-room faults; Danfoss — heat exchangers and possible abnormal-pressure causes. Manufacturer guidance is a general technical aid, to be related to the ship’s plant.

Practical Example

Learning scenario. After provisions are loaded, a cold room struggles to regain its required temperature and the compressor keeps running. Frequent door openings and ice on the evaporator have been observed: these are factors to assess, rather than proof of insufficient refrigerant.

During familiarisation, personnel reconstruct the load and trend, locate airflow and defrost on the diagram and compare the data required by the manual. Appointed personnel decide checks and actions; provision condition and preservation measures follow onboard procedures. The report separates observations, verified cause, work and outcome.

Information to reconstruct	Useful evidence
Service and symptom	Room, period, temperature trend and running/alarm status.
Context and diagnosis	Load, doors, circulation and defrost; checks made and confirmed or still suspected cause.
Outcome and follow-up	Performance verified after work, remaining defects and PMS link; any refrigerant quantities in applicable records.

The example sets no universal provision temperature and prescribes no top-up or settings. If the equipment contains ODS and falls under VI/12, maintenance or recharge is also an event to record without delay in substance mass; an HFC does not belong in the ODS record book simply because it is a refrigerant.

What Typically Goes Wrong

A common problem is confusing a symptom with its cause: “not cooling” immediately becomes “needs gas”, although doors, ice, airflow or heat rejection may explain poor performance. A protective trip or a fault recurring after a top-up needs the prescribed follow-up, rather than alarm clearance alone.

Records can also mix three different matters: PMS defects and maintenance, the ODS record book and F-gas duties. Identifying the refrigerant and activity avoids applying every EU rule to every ship or treating a service-use gas prohibition as automatic plant shutdown.

Common Mistakes Mistake Library

Mistake	Consequence	How to Avoid It
Adding refrigerant because the room does not cool, without establishing the fault.	The cause may remain unresolved and an incorrect charge may worsen operation.	Assess load, flows, heat exchangers, controls and circuit together; work follows the manual.
Confirming service solely because the compressor runs.	The room may remain outside the required conditions.	Verify the trend, alarms and service performance after work.
Replacing refrigerant solely because it has lower GWP.	Compatibility, controls and risks may change.	Assess conversion, components, oil and safety with competent parties.
Using an ODS record for every refrigerant or extending the entire F-gas regime to every ship.	Records and duties may not match the substance and activity.	Distinguish ODS/HFC, ship plant/reefer and territorial scope.
Treating every high-GWP gas as banned from 2020 or confusing servicing with use of the existing charge.	Work or shutdown may be ordered without checking the relevant provision.	Read the category, date, threshold and derogations; check reclaimed/recycled gas documentation.

What the PSCO Checks

For ODS equipment, the 2025 PSC procedures provide for checks of applicable documents and, during a more detailed inspection, effective maintenance and absence of deliberate emissions. IMO A.1206(34), appendix 18, §§2.1 and 2.6.1.

Equipment and substance identification consistent with the list, IAPP Supplement and ODS record book, where required.
Maintenance, recharge, recovery and delivery ashore traceable in relevant records; open defects and corrective actions visible.
Personnel able to explain the service, risks and assigned duties; plant instructions and data accessible.

The outcome and scope depend on the inspection and applicable requirements. Do not assume that every HFC plant needs an ODS record book or that the PSCO universally applies EU leak-check deadlines.

Operational Tips

Separate current rules, manufacturer instructions, class and SMS: general technical sources aid understanding but do not set plant limits.
At watch handover, report affected rooms, trends and defects/inhibitions alongside standby status.
Record deviations and corrective actions; avoid repeated top-ups without reconstructing fault follow-up.
Keep the equipment identifier, refrigerant, quantities added/recovered and supplier documentation consistent.
Do not improvise tests, thresholds or intervals; verify effectiveness after work and availability of leak/alarm instructions.

Preparation checklist

Plant diagram, refrigerant and manual identified.
Rooms served, required conditions, sensors and alarms understood.
Cycle, air/water flows, defrost and drainage located.
Operating data and diagnostic method connected to the instructions.
Defects, standby units, maintenance and outcome verification traceable in PMS/SMS.
ODS/HFC distinguished; ODS record and any F-gas regime checked for substance and activity.
Ship plant/reefer distinguished, including the relevant EU check date.
For service with high-GWP gas: relevant Article 13, derogation conditions, origin and label checked.

FAQ

Is EU flag enough?

No. Check operator, equipment, activity and jurisdiction. A plant fixed to a ship and a reefer do not automatically belong to the same category; distinguish general duties from those of listed categories.

Does every ship plant have EU periodic leak checks?

Not automatically: check Article 5 categories, thresholds and exemptions. For reefers in Article 5(3)(b), paragraphs 1 and 6 do not apply to operators until 12 March 2027; this does not suspend relevant general Article 4 duties.

Is a refrigerant with GWP ≥2500 always prohibited?

No. For refrigeration, Article 13(3) distinguishes the service-use prohibition from the existing charge and retains exclusions and conditional derogations for reclaimed/recycled Annex I gases until 1 January 2030. Air-conditioning and heat pumps have the different Article 13(4); also check other applicable supply and use rules.