Expanders can be supplied as single or multistage variants for axial or radial configurations. They are used in coal and oil gasification plants, nitric acid plants, therephthalic acid plants, fluid catalytic cracking plants, and blast furnace top gas plants. Process-gas screw compressors are oil-free and used where contaminated gases would curtail other compressor types. They attain flows up to 100,000 m3/h and pressures to 50 bar in refineries, petrochemical plants, chemical production, oil and gas production, iron and steel plants, and mining.