Installations and apparatus included in Class 11, all for heating, drying, humidifying, de-humidifying, hardening and cooking; installations and apparatus, all for ventilating and refrigerating; heat exchangers (not being parts of machines); all for use in the treatment of gases; warm air furnaces (not for experimental or test purposes); air filters, fans and air grilles, all include in Class 11; air dampers and dust filter bags, all being parts of ventilating installations; drying and conditioning installations for the treatment of cellulose and the like fibrous materials, of paper cardboard, grain, lumber, veneer and of wallboard; all the aforesaid goods utilizing a pulsating action or incorporated pulsating devices.