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R22 polution of R717 refrigeration systems. How can it happen? How do R22 and R717 react in the system? What will be the “sympto m s” on the system? How do we solve the problem if R22 gets into a R717 system? How do we avoid R22 gets into the system?. C. C.
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R22 polution of R717 refrigeration systems • How can it happen? • How do R22 and R717 react in the system? • What will be the “symptoms” on the system? • How do we solve the problem if R22 gets into a R717 system? • How do we avoid R22 gets into the system? C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
How can R22 get into a R717 refrigeration system? • During service and maintenance: • Using the same hoses, containers, tools and pressure vessels when working on both R22 and R717 systems • When second hand components from R22 systems are fitted on R717 systems • Accidents, where the wrong refrigerant is charged to the system • Direct from the supplier of refrigerant: • Supplier can use same charging system for R22 and R717 • Pressure vessels used for both R22 and R717 • When changing refrigerant: • Failing to get all oil and R22 out of a system which is changed to R717. C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
NB: Reaction products are aggressive or very poisonous How do R22 and R717 react in a R717 system? Reactions will take place where R717 is in the liquid phase: R22 + R717 => AMMONIUM + AMMONIUM + AMMONIUM CYANIDE CHLORIDE FLOURIDE CHClF2 + 5NH3 => NH4CN + NH4Cl + 2NH4F Will react with iron Dissolves in NH3 liquid Colorless crystals Colorless Very corrosive crystals Precipitates C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
NB: Reaction products are aggressive or very poisonous Ammoniacyanide will react with iron in the system R22 + R717 + IRON => AMMONIUM + AMMONIUM + AMMONIUM + HYDROGEN FERROCYANIDE CHLORIDE FLOURIDE 6CHClF2+28NH3+Fe =>(NH4)4Fe(CN)6 + 6NH4Cl + 12NH4F + H2 Dissolves in Dissolves Colorless Non- NH3 liquid. in NH3 liquid Crystals conden- Yellow color. Corrosive Precipitates sible gas Color change slowly to grey/blue when ex- posed to air. C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
NB: Reaction products are aggressive or very poisonous Ammoniumferrocyanide can react further: R22 + R717 + IRON => IRONBLUE + AMMONIUM + AMMONIUM + HYDROGEN CHLORIDE FLOURIDE 18CHCLF2+72NH3+7Fe => Fe4(Fe(CN)6)3+ 18NH4Cl + 36NH4F + 9H2 Crystals Dissolves Colorless Non Strong blue in NH3 liquid crystals condens- Precipitates Corrosive Precipitates ible gas C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
How much is created? Every kg R22 in a R717 system will create : 0,62 kg AMMONIUMCHLORIDE NH4Cl 0,86 kg AMMONIUMFLOURIDE NH4F 1 kg R22 => AMMONIUMFERROCYANIDE (NH4)4Fe(CN)6IRONBLUE Fe4Fe(CN)6 0,004-0,012 kg HYDROGEN H2 0,55 kg C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Where do the reaction products settle? AMMONIUMCHLORIDE Settles as porous crystals where NH3 NH4Cl liquid evaporates, mainly in expansion AMMONIUMFERROCYANIDE devices and evaporators (NH4)4Fe(CN)6 AMMONIUMFLOURIDE Settles as crystals in the NH3 liquid where NH4F they are created, mainly in high pressure IRONBLUE receiver and high pressure liquid line. Fe4(Fe(CH6))3 HYDROGEN H2 Assembles as non condensible gas in condenser and / or receiver C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Secondary Effects In the presense of zinc, Zincammoniumchloride Zn(NH3)2Cl will be created: Zincammoniumchloride Zn(NH3)2Cl Have a flux effect => reactive surfaces on metals Ammoniumchloride Creates a very corrosive environment NH4Cl Valves, regulators etc. can get “stuck” du to excessive corrosion. C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Excessive Corrosion Pistons from PM valves exposed in two weeks to the corrosive environment of a R22 poluted R717 system. C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Practical examples of damage on systems Blue coloring Blocked by corrosion Check valves blocked Sludge Compressor bearing break down Pump damage Blue coloring Sludge Blue coloring Housing filled with sludge Blue coloring and corrosion Big amount of sludge Pipe blocked Pipes and valves totally blocked C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
NB: Reaction products are aggressive or very poisonous How to clean the system? AMMONIUMCHLORIDE NH4Cl: Dissolves in water AMMONIUMFLOURIDE NH4F Dissolves in cold water and AMMONIUMFEEROCYANIDE decompose in hot water (NH4)4Fe(CN)6 IRONBLUE Fe((Fe(CH6))3: Will not dissolve in water, mechanical cleaning necessary Corrosion products: Mechanical cleaning C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Conclusions: • R22 pollution of R717 systems can happen • The quantity of reaction products is high • Very corrosive environments can be created in the plant • Valves, filters, controls and pipes can get blocked • Compressors and NH3 pumps can be damaged • Valves and controls can get stuck in corrosion • System cleaning difficult and expensive C C ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415