Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Servicing of HCFC/HFC Based Air-conditioners

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP Recovery of HCFC/HFC Refrigerant 2.Cleaning and flushing 3.Repair 4.Flushing and choke testing 5.Leak Testing 6.Evacuation & Vacuum holding 7.Charging Refrigerant 8.Sealing of process tube 9.Checking for proper Operation Steps of Servicing

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Recover HCFC/HFCs as these are global warming gases Use piercing pliers or piercing valve, Use Recovery machine & a recovery cylinder The process of recovery is similar of HCFC and HFC with the oil-less recovery machine. Recovery Recovery of HCFC/HFC Refrigerant

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Drier must be removed when pressure drop exceeds rated amount After de-brazing of the old filter or drier –Use dry Nitrogen with two stage regulator, at a pressure of about 5-10 bar –Use ODS free substance where chemical cleaning is required –Do not use R141b, CTC, air or petrol In case of R32 be very careful with de-brazing (follow extra step like HC charge) because of flammable nature Cleaning and flushing

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Carry out the necessary repair with the system. Change the filter drier in case of medium commercial HCFC/HFC based appliances. (use always activated alumina drier for HCFC and molecular sieve drier for HFCs ) Repair the system

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Introduce oxygen free dry nitrogen (OFDN) through the process tube and ensure free passage at the process tube of the double mouth filter drier in case of small commercial appliances and from T joint of window air- conditioner. See the nitrogen coming out of both sides. Use oxygen free dry Nitrogen (OFDN) with two stage regulator Choke Testing To ensure no chokes during brazing

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Why does leakage occur? Vibration Poor brazing Poor connections Poor workmanship Corrosion Accidental damage

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Pressure Testing Pressure Testing and Leak Detection open closed open High pressure side Low pressure side

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Pressurize the system to maximum of 20 bar with oxygen free dry nitrogen (OFDN) & close the cylinder valve when the gauge reading reaches 20 bar. For R410 it can be 43 bar. Apply a soap water or a liquid neutral detergent on the RAC system connection, joints and flares or outdoor unit connections by a brush to check for leakage. If bubbles come out, a leakage is indicated. Pressure Testing and Leak Detection

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014  Fluorescent dyes  Oil stains  Electronic leak detectors Different Methods - Leak Detection

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Evacuate the system to 1000 microns from both service valves. To measure the vacuum a vacuum gauge must be used at all times - do not use manifold gauge. After evacuation hold the same for five minutes. And see the rise. If it goes up very quickly then check the leakage again. Deep vacuum important due to hygroscopic nature of polyol ester oil as well as for HCFCs to get optimum performance. Two stage rotary vacuum pump - capable of developing blank off pressure of microns, minimum capacity 2cfm Micron gauge capable of reading pressures in microns or other scales EvacuationEvacuation – HCFC/HFC

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Evacuation – 1st step

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Evacuation – 2nd step

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Recommended Evacuation – R410A Step 1: Evacuate the system to 1000 microns from both service valves. To measure the vacuum a vacuum gauge must be used at all times - do not use a system manifold gauge. Step 2: Break the vacuum with OFN to 14 PSIG Step 3: Evacuate to 500 microns Step 4: Repeat Step 2 Step 5: Evacuate to the lowest pressure that the pump will achieve (200 microns for a minimum of 1 hour) Step 6: The rise test must then be carried out for a minimum of 30 minutes

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Charging Charging by weight

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Charging apparatus must be used for accurate charging such as weighing scales or calibrated charging cylinders Charging by volume

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 It is essential when using Blends that the system be liquid-charged by removing only liquid from the cylinder. Never charge the system with vapour from a cylinder. The liquid can be “bomb (pump) charged” via liquid line (liquid injection into the high pressure side of a system after it has been evacuated) Vapour-charging may result in the wrong refrigerant composition and could damage the system. To avoid over charging, do not attempt to clear the sight-glass when charging a system with a blended refrigerant. Charging with Blends (HFCs)

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Charging with HCFC Charge evacuated systems only Charging should be done slowly / gradually Accurate charge quantity by weighing or calibrated volumetric still Charge single substance by vapour

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Avoid Overcharging !!! undercharging a relatively low condensing pressure exists. If refrigerant is charged the condensing pressure rises until a given liquid level is obtained in the receiver. While the receiver is being filled the pressure remains constant. Once the receiver is full, refrigerant backs up into the condenser, the useful condenser area is reduced and the condensing pressure rises further.

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Braze (for window air-conditioner) Crimp (preferably twice) Do not remove crimping tool until tube is sealed Check for leaks Sealing Process Tube Tightening of Valves (for split air-conditioner) Close the valve properly. Cap the valve Check for leaks

Chapter 4 Training Package HCFC Phase-out RACSS – UNEP 2014 Checking Proper Operation Grill temperature Check compressor current Check no extra vibrations.