Refrigerated shipping containers specially designed for transporting perishable goods across the seas and via intermodal transport are referred to as “Reefers”. To preserve the freshness and original state of such perishable cargo, frequent inspection and maintenance of reefers assume principal importance to everybody involved in the cold storage supply chain process.
On the ship, reefers must perform flawlessly to make sure that the cargo arrives at its destination without deterioration in quality. Pre-Trip Inspections on reefers is a mandatory practice carried out to ensure that such units are functioning satisfactorily before they are handed over to the shipper for loading the cargo.
Routine reefer maintenance guarantees optimum performance and ensures long serviceable life. Let’s know about the various components inside a reefer unit and the tasks they perform:
The compressor is the most important section of an air-conditioning unit. It is a pump that circulates the refrigerant in the unit and works by increasing the pressure and temperature of the vaporized refrigerant. It integrates a modulating and suction solenoid valve for controlling the quantity of refrigerant gas flow. Safety accessories in the compression section comprise moisture liquid indicator, pressure release valve and filter drier. Other devices like compressor suction and discharge sensors, supply air temperature sensors and ambient sensors assist to check the safe working of the compressor unit.
This is the cooling component of the refrigeration system. It consists of a temperature sensing bulb, return recorder bulb sensor and a thermostatic expansion valve that controls the flow of refrigerant and maintains the set temperature. Its components are an evaporator coil and heater, defrost and heat transmission switches. The evaporator fan dispenses air inside the container by drawing air on top of the refrigeration unit and directing the air through the evaporator coil.
It comprises a set of coiled tubes that cools the vaporized refrigerant and converts it back to liquid form.
Fresh air vent:
Such vents supply air ventilation for goods requiring clean air circulation. It must however remain closed during transporting of frozen goods.
Let’s examine some best practices to follow while carrying out maintenance and repair of reefer containers:
- Power supply must be disconnected during maintenance.
- Safety glasses and gloves must be worn when charging the
- Keep a safe distance from the condenser fan and evaporator.
- Disconnect all wire harness from the module in the control box while welding the unit or the compressor.
- While detaching the wire harness from the module, wear a wrist wrap that is static-safe.
- Refrigerants such as phosgene gas carry certain risks if inhaled, so the staff involved in the maintenance should exercise caution.
- If there is an electrical fire, quickly open the circuit switch and use a CO2 fire extinguisher.
- Compressed gas bottles need careful handling when charging the refrigerant.
To lessen the possibility of refrigerant gas leakage, attention must be paid during the inspection of pipes in the course of routine maintenance. Suspected pipelines are sprayed with soap water to detect bubbles and identify the exact location of the leakage. Other leak detectors used are halide lamps and portable electronic leak detectors.
Smooth and unhindered airflow inside reefers determines how well they function to maintain the optimum temperature. Maintenance staff has to devote special attention to this area of operation. The right temperature control, air exchange and circulation matter the most. Moisture, water and condensation inside reefers can spoil the cargo by the accumulation of mold, bacteria and weaken the packaging material. The reefers must be clean, dry and in good condition before delivery to customers.
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iDepo keeps track of pre Trip Inspections, Repair & maintenance of dry and reefer containers. iDepo incorporates EDI (Electronic Data Interchange) capabilities that seamlessly yield transparency, accuracy and speed in day-to-day depot operations empowering asset owners to stay on top.