TYPE II SYSTEM SCOPE
Medium, High, and Very-High Pressure systems.
Common refrigerants: R-22, R-404A, R-407C, R-410A, R-717.
LEAK CATEGORIES & MAXIMUM LEAK RATES
Comfort Cooling: 10%
Commercial Refrigeration: 20%
Industrial Process Refrigeration (IPR): 30%
Leak rules apply to systems with 50 lb or more refrigerant.
LEAK REPAIR REQUIREMENTS
• Must repair leaks to below threshold.
• Repair and initial verification test must be completed within 30 days.
• Follow-up verification test required within 10 days (systems with 200 lb or more).
• All records must be kept for 3 years by the owner.
• Mothballing is allowed — recover to atmospheric pressure to pause the 30-day clock.
• Retrofit or retire deadline is 18 months if switching refrigerants.
LEAK DETECTION
• Use dry nitrogen with a small amount of system refrigerant.
• Never use oxygen or compressed air (explosion hazard).
• Oil stains indicate a leak.
• Use soap bubbles or an electronic leak detector to pinpoint the leak.
RECOVERY LEVELS (VACUUM REQUIREMENTS BEFORE OPENING SYSTEM)
Very High Pressure Refrigerants: 0″ Hg
High Pressure, under 200 lb: 0″ Hg
High Pressure, 200 lb or more: 10″ Hg vacuum
Medium Pressure, under 200 lb: 10″ Hg vacuum
Medium Pressure, 200 lb or more: 15″ Hg vacuum
If system leaks prevent achieving these levels: recover down to atmospheric pressure.
RECOVERY TECHNIQUES
• Recover liquid first, then vapor.
• Use short, large-diameter hoses for faster recovery.
• Cool the recovery cylinder and warm the system to improve flow.
• Close equalization lines on parallel compressor racks.
• Always use low-loss fittings.
• When switching refrigerant types, empty and evacuate the recovery machine and replace the filter.
EVACUATION (DEHYDRATION)
• Pull vacuum to 500 microns or less.
• System must hold vacuum (no rebound).
• Slow rise = moisture.
• Steady rise = leak.
• Use nitrogen breaks if moisture freezes while evacuating.
MAJOR COMPONENTS & WHAT TO REMEMBER
Receiver: stores liquid after condenser.
Filter-drier: removes moisture and acid; replace any time system is opened.
Sight glass: bubbles = low charge; color change = moisture.
Accumulator: prevents liquid flood-back to compressor.
Crankcase heater: prevents refrigerant migration into oil.
Relief valves: never in series — only in parallel.
EVACUATION BEFORE MAJOR REPAIR
High-pressure system with more than 200 lb refrigerant: 10″ Hg vacuum.
High-pressure system under 200 lb: 0 psig is acceptable.
CHARGING & PT CHART USE
• When charging from vacuum: add vapor first.
• For R-410A chilled water systems: add vapor until system is around 110 psig (to avoid freezing water), then switch to liquid charging by weight.
• Always verify pressures with a PT chart.
• Always charge refrigerant by weight according to nameplate.
SAFETY REQUIREMENTS
• Nitrogen cylinders must have regulator and relief valve.
• Wear gloves and eye protection.
• Cylinders must be filled to no more than 80% capacity.
• Recovery cylinder color: yellow top, gray body.
• Do not mix refrigerants in a cylinder.