To produce glass wool from melted glass, low-pressure air at 2.5 bar g is used. For this process the air must not be polluted; this means the air must also be oil free. Therefore the use of oil-injected or oil-lubricated compressors is not an option.
When the main compressor in a glass wool manufacturing plant broke down, replacing its air capacity had to be done quickly because the standby supply was not sufficient for full production to continue during the overhaul period.