SEPARATE VERTICAL TYPE SUPPLY AND EXHAUST DUCT FOR MULTIPLE DWELLING

Japanese Patent JP3802181

B2

PROBLEM TO BE SOLVED: To keep a differential pressure between the supply side and the exhaust side in a specified range by mounting a negative pressure regulating device at the bottom of an exhaust duct. SOLUTION: A negative pressure regulating device 7 is mounted on an atmosphere release port 3c formed in a part of a bottom 3b of an exhaust duct 3. Further, a damper 8 is rotatably (openably) mounted in a chamber 7a by a spindle 12. A balancer 9 is mounted removably from a damper 8. When a negative pressure is regulated, a total weight is changed through exchange with an object having a different weight or increasing or decreasing a quantity. Further, a coil spring is inserted between the mounting piece of the damper 8 and a spindle plate and the self-closing force of the damper 8 is regulatable by the force of the coil spring. This constitution keeps a negative pressure in the exhaust duct 3 at a constant value by opening and closing the damper 8 according to a differential pressure between the interior of the exhaust duct 3 and an atmosphere pressure and regulates such that a negative pressure in the exhaust duct 3 is prevented from being too increased.