Commissioning of refrigeration system

Need for commissioning

Basically, refrigeration systems are used for industrial and commercial facilities. The design of each industry differs from Industry to industry. Refrigeration system is also custom – engineered for each application. Equipment selected for individual projects are as per project needs. Due to this customised nature of the design, commissioning plays important role to run the refrigeration system as per design and customer’s expectation. Each project become unique project due to customised equipment like, condenser, evaporator, flow control, type of refrigerant. These leads to infinite variation in the system. Refrigeration system can be set as per the customer requirement to avoid additional uses of electrical energy.

KEY INSTALLATION METHODS BEFORE COMMISSIONING

• Dry nitrogen purging during brazing process to minimise oxidation in the piping.
• Proper drain line piping to the receiver from the condenser to the receiver.
• In case for superheat measurement, access ports should be at high point.
• Proper support for piping to allow proper oil return to the compressor.
• Use branded material (copper tube type, long radius elbows, etc.).
• Pressure test all assembled and brazed piping to 300 psig (2069 kPa gauge) for 24 h.
• Check power, communications, and control wiring.
• Locate sensors as per design, with proper mounting
• Install all wiring, cables, wire labels, grounding, and sensor connections, as well as provide correct grade materials.
• All cases should be sealed and leveled properly.
• Condenser should be leveled properly
• Compressor systems should be leveled and secured properly with proper safety and electrical clearances.
• Proper vacuum measurement is critical to understand refrigeration system’s readiness.
•  Measuring gauges must be calibrated.

Improper tested system will have maintenance issue.

During the commissioning procedure follow the manufacturer recommendations. Following are the point need to follow.

• Before starting the system check compressor oil level from the sight glass also inspect it when system has reached the steady state of operation. Oil level should be slightly above the center of the sight glass.
• Once system is started check the compressor current. It should be in range specify by manufacturer.
• Check the system’s initial suction pressure, discharge pressure. When system has reached the steady state of operations, verify final suction pressure and discharge pressure.
• Check evaporator superheat values are correct.
• In case condenser is installed outdoor and the ambient is low, condenser need to block partially for proper sub-cooling value.
• Verify all electrical connections.
• Check temperature controls are operating properly by cycling the system off and then back on.
• Check solenoid valve’s functionality whether compressor go off on low right pressure.
• Check the defrost system if system is a negative temperature system.
• Check high pressure safety if it is incorporated in the system. In air cooled system fan motor can be disconnected or condenser inlet can be blocked to check high pressure cut off. In water cooled system disconnect or shut off the water supply.