Air cleaning machines and apparatus, namely, air cleaning units; air ventilation apparatus and instruments; apparatus for the exhaust and filtering of smoke, dust, fumes and gasses, namely, industrial air filter machines; apparatus for the exhaust of exhaust gases, namely, ventilating exhaust fans; [ apparatus for the exhaust of smells and vapors for large-scale kitchens, namely, ventilating exhaust fans; ] air filter systems, namely, air filters for industrial use; air purifiers