The 150-year-old organisation was using refrigerant based on dichlorodiflouro methane gas, which is harmful to the ozone layer causing its depletion.
"The dichlorodiflouro methane (R-12) is not environment friendly. If it leaks out during break downs or accidents, it will deplete the ozone layer around the stratosphere," a Northern Railway official said.
"The new refrigerants called R-134A and MO-49 are more eco-friendly. We have converted 11 coaches equipped with conventional under-slung AC plants with eco-friendly refrigerants," the official said.
The Northern Railway has a fleet of 1,169 AC coaches. Out of 1,169, 302 coaches (116 Self Generating, 122 End-On Generation and 64 generators cars) are equipped with conventional type of under-slung AC plants.
The conventional under slung AC plants use dichlorodiflouro methane-based refrigerant. The self generating air-conditioned coaches are attached to long distance trains and are 485 in number whereas, the end -on generation coaches are 560 in number and are used in Rajdhani, Shatabdi and Garib Rath trains, the official said.
Power cars, numbering 94, are used to generate extra energy required in Rajdhani, Shatabdi and Garib Rath trains, the official said. Such trains have two generators of power cars to provide the required power supply throughout the journey.
"We are planning to convert rest of the coaches by March next year," the official said. Of the rest, 767 coaches are equipped with Modern Roof Mounted Package Unit type of AC plants, which uses chlorodiflouro methane based refrigerants, which is eco-friendly.
The depletion of the ozone layer, which blocks the entry of harmful infrared radiations of the sun towards the earth and thus acts as heat insulation for keeping the temperature of the earth under control, would disturb the ecological balance.