IS 660 prescribes the essential safety requirements for the design, construction, installation, operation, and inspection of mechanical refrigeration systems. Engineers use this code to ensure adequate plant room ventilation, safe routing of pressure relief discharges, and proper refrigerant handling to prevent asphyxiation, toxicity, and explosion hazards.
Lays down safety requirements for the design, construction, installation, operation, and maintenance of mechanical refrigeration systems.
Quick Reference Values
pressure gauge dial limit1.2 times the design pressure (minimum)
relief valve settingNot exceeding the design pressure of the vessel
leak test pressureNot less than the design pressure
ammonia factor f for relief valves0.5
freon factor f for relief valves1.6
Key Formulas
C = f × D × L — Minimum required discharge capacity of the relief device (kg/air/min)
Practical Notes
Ensure safety relief valves on systems containing toxic or flammable refrigerants (like Ammonia) discharge safely outdoors, above the roofline and away from fresh air intakes.
Group 2 and Group 3 refrigerants strictly require dedicated machinery rooms with gas leak detectors, emergency isolation, and mechanical ventilation.
Never use oxygen or combustible gases to pressurize refrigeration lines for leak testing; always use dry nitrogen.