R11 (also known as Freon-11 or CFC-11) was still available for some specialized applications, but its production and usage were significantly restricted due to its harmful effects on the ozone layer. R11 is a chlorofluorocarbon (CFC) refrigerant, and it has a high ozone depletion potential (ODP), contributing to the depletion of the Earth's ozone layer when released into the atmosphere.
The Montreal Protocol, an international treaty established in 1987, aimed to protect the ozone layer by phasing out the production and consumption of ozone-depleting substances, including CFCs like R11. Many developed countries had already banned the production and import of R11, and its use was limited to certain critical applications where no suitable alternatives were available.
Instead of using ozone-depleting substances like R11, the refrigeration industry has transitioned to safer refrigerants with lower or no ODP, such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). However, these refrigerants, especially some HFCs, are potent greenhouse gases with high global warming potential (GWP), contributing to climate change.
In recent years, there has been a growing push to phase out HFCs as well and replace them with more environmentally friendly refrigerants, such as hydrofluoroolefins (HFOs) and natural refrigerants like hydrocarbons (propane, isobutane) and carbon dioxide (CO2).
Due to the phase-out efforts, it's likely that R11 is even less available today than it was in the past. The specific regulations and availability of refrigerants can vary by country and region, so it's essential to consult local regulations and speak with refrigeration experts to determine the appropriate and environmentally friendly alternatives for specific applications.