HCFC Refrigerants

R22 as transitional refrigerant

Although chlorine-free refrigerants, such as R134a and R404A/R507A (Structural classification of refrigerants and Substitutes for CFC and HCFC refrigerants (chlorine free HFCs) (status as of 09.2018)) have been widely used − but are already being replaced by alternatives with lower GWP in the EU for example − R22 is still used internationally in many areas, both for new installations and for retrofitting existing ones.

Reasons are relatively low investment costs, especially compared with R134a systems, but also its large application range, favourable thermodynamic properties and low energy requirement. Additionally, R22 and components are available world wide, which is not guaranteed everywhere for the chlorine free alternatives.

Despite of the generally favourable properties R22 is already subject to various regional restrictions* which control the use of this refrigerant in new systems and for service purposes due to its ozone depletion potential – although being low.

With regard to components and system technology a number of particularities are to follow as well. Refrigerant R22 has approximately 55% higher refrigerating capacity and pressure levels than R12**. The significantly higher discharge gas temperature is also a critical factor compared to R12 (R12/R22 – comparison of discharge gas temperatures of a semi-hermetic compressor) and R502**.

Similar relationships in terms of thermal load are found in the comparison with HFC refrigerants R134a, R404A/R507A (R134a as substitute for R12 and R22 and R404A and R507A as substitutes for R22 and R502).

*Not allowed for new equipment in Germany and Denmark since January 1st, 2000 and in Sweden as of 1998. Since January 1st, 2001 restrictions apply to the other member states of the EU as well. The measures concerned are defined in the ODS Regulation 1005/2009 of the EU commision on ozone depleting substances amended in 2009. This regulation also governs the use of R22 for service reasons within the entire EU. Since 2010, phase-out regulations in other countries, such as the USA, are valid.
** Already banned in most countries.

Resulting design criteria

Particularly critical – due to the high discharge gas temperature – are low temperature plants especially concerning thermal stability of oil and refrigerant, with the danger of acid formation and copper plating. Special measures have to be adopted therefore, such as two stage compression, controlled refrigerant injection, additional cooling, monitoring of discharge gas temperature, limiting the suction gas superheat and particularly careful installation.