| 摘要 |
An air admittance valve device is disclosed for enabling valve sealing member to remain securely closed against high pressure in a pipe or duct produced from: equipment connected to said pipe or duct e.g. a hydraulic pipeline flusher device; fluid movement within, or as otherwise introduced to system of pipe or duct while further remaining tightly closed at normal atmospheric pressure (equilibrium) and equalizing pressure excursions that are below atmospheric pressure occurring within sanitary drainage pipes or room ventilation ducts by admitting air to said pipe or duct.
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