DuPont HFC: 134A Suva Refrigerants Dymel Propellant System

In 1980, HFC-134a was introduced by DuPont as a replacement for chlorofluorocarbons (CFCs) in many applications. CFCs, which were developed over 60 years ago, have many unique properties. They are low in toxicity, nonflammable, non-corrosive and compatible with other materials. In addition, they offer the thermodynamic and physical properties that make them ideal for a variety of uses. CFCs are used as refrigerants; as blowing agents in the manufacture of insulation, packaging and cushioning foams; as cleaning agents for metal and electronic components; and in many other applications.However, the stability of these compounds, coupled with their chlorine content, has linked them to depletion of the earth’s protective ozone layer. As a result, DuPont has phased out production of CFC sand introduced environmentally acceptable alternatives, such as hydrofluorocarbon (HFC) 134a. DuPont began producing hydrofluorocarbons as alternatives to Freon in the 1980s. These included Suva refrigerants and Dymel propellants.

HFC-134a—An Environmentally Accept-able Alternative

HFC-134a does not contain chlorine; therefore, ithas an ozone depletion potential (ODP) of zero.

Listed below are all generic and DuPont trade names:

  • Hydrofluorocarbon-134a
  • HFC-134a
  • HFA-134a

HFC-134a can be used in many applications thatcurrently use dichlorodifluoromethane (CFC-12).These include refrigeration, polymer foam blowing,and aerosol products. However, equipment designchanges are sometimes required to optimize theperformance of HFC-134a in these applications.

Stability with Metals and Refrigeration Lubricants

Stability tests for refrigerants with metals are typically performed in the presence of refrigeration oils. The results of sealed tube stability tests are available for CFC-12/mineral oil combinations,which have shown long-term stability in contact with copper, steel, and aluminum in actual refrigeration systems. Polyalkylene glycol (PAG) and polyol ester (POE) lubricants are used with HFC-134a.

Sealed tube tests were run to determine the relative long-term stability of HFC-134a/metals in the presence of these lubricants.The method followed was generally the same as ASHRAE 97 with several minor modifications. A3-mL volume of refrigerant/lubricant solution was heated in the presence of copper, steel, and aluminum strips in an oven for 14 days at 175°C (347°F).Both the neat lubricant and a mixture of lubricant and refrigerant (50/50 volume ratio) were tested.Visual ratings were obtained on both the liquid solutions and the metal coupons after the designated exposure time. The visual ratings ranged from 0 to 5, with 0 being the best.After the visual ratings were obtained, sample tubes were opened and the lubricant and refrigerant (ifpresent) were analyzed.