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

• 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?

R22 polution of R717 refrigeration systems

ooling M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com onsult Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415 CC

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.

How can R22 get into a R717 refrigeration system?


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

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.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



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)6

IRONBLUE Fe4Fe(CN)6

0,004-0,012 kg HYDROGEN H2

0,55 kg


Where do the reaction products settle?

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

AMMONIUMCHLORIDE Settles as porous crystals where NH3

NH4Cl liquid evaporates, mainly in expansion

AMMONIUMFERROCYANIDE devices and evaporators

(NH4)4Fe(CN)6


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.


Excessive Corrosion

Pistons from PM valves exposed in two weeks to the corrosive environment of a R22 poluted R717 system.


Practical examples of damage on systems

Pump damage

Blue coloring

and

corrosion

Blue coloring

Blocked by corrosion

Check valves blocked

Compressor bearing

break down

Blue

coloring

Pipe blocked

Housing filled with sludge

Sludge

Blue coloring

Big amount of sludge

Sludge

Pipes and valves totally blocked


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



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


Documents

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