Guidelines for equipment conversion to hydrocarbon refrigerants


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Guidelines for equipment conversion to hydrocarbon refrigerants (Daniel Colbourne, Consultant).

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Guidelines for equipment conversion to hydrocarbon refrigerants

  1. 1. UNEP South America Regional Workshop Low-GWP, Energy-Efficient HCFC Replacement Technologies in the Refrigeration and Air Conditioning Sector Guidelines for equipment conversion to hydrocarbon refrigerants 22nd – 23rd April, 2010, Bogota, Columbia Daniel Colbourne RE – PHRIDGE
  2. 2. Conversion to hydrocarbons Introduction • Issue of converting non-hydrocarbon systems to use hydrocarbons is very delicate! – Risk is considerably greater that with dedicated HC systems – Only if absolutely necessary and 101% sure it can be done safely! • Will discuss basic principles and warnings • Highlight importance of safe working • Recommended decision-making process for conversions – Function of type of equipment and sensible practices • Proper conversion process • Technician training guidelines – Priority issues to be aware of (ignition sources, marking, leakage, etc) – Concluding remarks
  3. 3. Conversion to hydrocarbons Note on terminology… • Recommend the term “conversion” be used – important as it distinguishes from other phrases such as “re-fill”, “drop-in” and “retrofit” • When non-flammable (say R12) replaced by another non- flammable (say R134a) – System changes relate to performance (e.g., capillary tube length) or compatibility (e.g., oil type) • When non-flammable (say R22) replaced by HC (say R290) – Additional considerations must be taken into account – Required changes are related to mitigating the flammability risk – A switch from non-flammable to flammable refrigerant should be considered as an entire conversion of the equipment
  4. 4. Conversion to hydrocarbons Basic principles and warnings • Reasons for wanting to retrofit – A desire to improve the efficiency of a system – To minimise the environmental impact – Because it may be more cost-effective than using other refrigerant options – If there are no other refrigerant replacements available • If existing system working correctly… – There is normally NO NEED to convert to use any alternative • Carrying out a system conversion to use HC necessitates careful consideration of implications – Essential to weigh up the risks and benefits – Can only take place if final product meets safety standards and national regulations
  5. 5. Conversion to hydrocarbons Warning – importance of safe working • Human behaviour has greatest influence on risk of ignition • Risk of ignition is function of – Probability of leak; size of flammable cloud; duration of flammable cloud; presence of sources of ignition * P Pleak ×PFV × PFt × Psoi • During servicing – Higher probability of leakage (breaking into system) – More refrigerant to leak (e.g., cylinders) – More sources of ignition (service equipment) – Etc • Overall, risk of fire 10 to 1000 higher during servicing – Therefore, essential to focus on reducing risk whilst servicing
  6. 6. Conversion to hydrocarbons Considerations affecting conversions • Important to follow a logical sequence of safety-related considerations to help make the correct decision – Type and complexity of the equipment – Environment and installed location – Quantities of refrigerant (in relation to the system location) – Necessity to introduce additional emergency systems – Ease or possibility of modifying parts of the system – Ease or possibility of handling the potential sources of ignition • Other aspects may also need to be considered
  7. 7. Conversion to hydrocarbons Flow chart – checks (for small systems only)
  8. 8. Conversion to hydrocarbons Recommendations for different equipment Sector Equipment type System type Viability Chiller cabinets Integral  Domestic refrigeration Freezer cabinets Integral  Chiller, freezer cabinets Integral  Chiller, freezer cabinets Remote  Retail refrigeration Chiller, freezer cabinets Distributed  Chiller, freezer cabinets Indirect  Storage cabinets Integral  Coldstores Remote  Coldstores Distributed  Cold storage and food Coldstores Indirect  processing Process cooling/freezing Remote  Process cooling/freezing Distributed  Process cooling/freezing Indirect  Road transport trucks Integral  Refrigerated railcars Integral  Transport refrigeration Reefer containers Integral  Marine refrigeration Integral 
  9. 9. Conversion to hydrocarbons Recommendations for different equipment Sector Equipment type System type Viability Portable units Integral  Window units Integral  Through-wall units Integral  Split units Remote  Multi-split/VRV Distributed  Air conditioners, dehumidifiers and heat Packaged ducted Remote  pumps Central packaged Remote  Positive displace chillers Integral/Indirect  Centrifugal chillers Integral/Indirect  Hot water heating Integral  Central heating Integral/indirect  Cars Remote  Buses Remote  Transport air conditioning Trains Remote  Aeroplanes Remote 
  10. 10. Conversion to hydrocarbons Procedure for conversion
  11. 11. Conversion to hydrocarbons Workshop conversions only • Remove appliance to special workshop for refrigerant system operations – Safety facilities; working area properly set up to handle flammable refrigerants (ventilation, gas detectors, etc) – Better access to proper tools, equipment and required components – No untrained persons, or, expert technicians that specialise in HCs – Less risk (and hassle) for customer
  12. 12. Conversion to hydrocarbons Develop “conversion kits” • Sensible approach for companies that carry out regular conversions • Good idea to produce “conversion kits” – Tailored for specific types of equipment – Helps prevent technician from taking short-cuts • May contain: – Electrical components – IP67 boxes and grommets – Flammable gas stickers – Risk assessment – Instruction sheets
  13. 13. Conversion to hydrocarbons Develop written risk assessment for technicians • Teach technicians on how to carry out qualitative risk assessment • BEFORE any work is done… – Identify situations at risk – Consider likelihood of small… medium… large… leaks – Where may leaks come from? Check list – Where are sources of ignition? 1. What about leaks? – When will they be active? 2. What about – What about occupants? SOI? – What happens if something ignites? 3. What about people? • Should produce basic risk assessment forms 4. Etc… – Available for each activity
  14. 14. Conversion to hydrocarbons Schemes – working procedure instructions • Essential to have concise, easy to follow, “appealing” instructions for workers – Provide safe work instructions – Manual of procedures for each situation that is likely to arise • To cover installation, servicing, maintenance, decommissioning – Charging – Recovery, evacuation – Strength (pressure) testing – Tightness (leak) checking – Also brazing, removing oil, etc • Must have coordination with two or more
  15. 15. Conversion to hydrocarbons Equipment marking and signage • Make sure signage is as required • Essential for raising awareness of presence of flammable gas – Technician should not be able to get to refrigerant-containing parts without seeing EXTREMELY FLAMMABLE “flammable gas” sign R290 REFRIGERANT • Ensure appropriate marking – System (vessels/access panel); at least 2 “flammable gas” stickers – Machinery rooms; safety signs specific to refrigerant type, pressures, charge size – Piping; “flammable gas” sticker where people eg, near access could break into pipe point
  16. 16. Conversion to hydrocarbons Leak detection • Understand what is being done • Gas detection is not leak detection! – Leak detection = gas detection + person – Gas detectors assist with leak detection, they don’t do it all! + = • Repairing leaks very important – Safety – Performance (5% leakage, 10% higher energy consumption)
  17. 17. Conversion to hydrocarbons Leak detection • Carry out thorough leak checks – Understand how to spot them, where they normally occur from…
  18. 18. Conversion to hydrocarbons Equipment electrics & other sources of ignition • On/Off manual switches  • Liquid level switch • Condensate pump switch • Thermostats • Pressure switches • Oil differential switches  • Fan delay switches • Contactors • Fan motor (not induction) • Defrost timers • Capacitors  • Time switches/relays X • Start relays • Thermal overload relays • Potential relay • Universal relay • Fan speed controllers Glowing defrost heaters • Humidity controllers NOT ACCEPTABLE
  19. 19. Conversion to hydrocarbons Refrigerant charging • Use the most suitable charging method • Depends upon – Type of system – Available equipment – Required accuracy Pressure, Mass flow Weight Volumetric Sight glass temps
  20. 20. Conversion to hydrocarbons Refrigerant charging • Essential to use the correct charge size – Safety and performance reasons – Use the formula, based on original charge MHC = Mdp × Cf HC refrigerant Fluorinated refrigerant R600a/R290 R290/R170 R600a R290 R1270 (50%/50%) (94%/6%) CFC-12 (0.43) † 0.40 n/a n/a n/a HFC-134a (0.47) † 0.45 n/a n/a n/a HFC-1234yf (0.53) † 0.50 n/a n/a n/a HCFC-22 n/a n/a 0.42 0.41 0.42 HFC-407C n/a n/a 0.45 0.44 0.45 HFC-404A n/a n/a 0.51 0.50 0.52 HFC-507A n/a n/a 0.51 0.50 0.52 HFC-410A n/a n/a (0.49) † (0.50) † (0.52) † †Would require change in compressor displacement n/a: HC refrigerant not applicable to system using existing fluorinated refrigerant
  21. 21. Conversion to hydrocarbons Technician training guidelines • Important to cover wide extent of topics for technician training i. General refrigerant safety and safe handling ii. Flammable gas fundamentals and HC characteristics iii. Requirements of safety standards iv. Working area and checks + v. Service equipment vi. Refrigerant cylinders (transport and storage) vii. System and equipment checks viii. Equipment marking and signage ix. Gas detectors and leak detection x. Electrical equipment and other sources of ignition xi. Refrigerant handling (recovery, venting, evacuation, breaking into system, charging, dismantling) • Also must include practical (hands-on) training and practise
  22. 22. Conversion to hydrocarbons Concluding remarks • Conversion of systems must only be carried out, only… – By very well-trained technicians, experienced with HCs – When it is absolutely necessary to do so – With proper, correct equipment – Using the safest, most appropriate methods • Be aware of the safety risks – Risk much higher during service/maintenance than during normal use – Converted equipment always less safe than specially designed units • Authorities must put proper rules in place – Training, strategies, procedures, registration schemes, etc, – Include thorough rules regarding use and working with flammables – Phase-in use of HCs according to system size and complexity