| 摘要 |
A pressure and vacuum vent utilizing a column of liquid to open and close the vent at predetermined pressure and vacuum levels. A column of liquid is constrained in connection with internal and external passages coupled between a pair of expansion chambers. The external passage is sized to hold a level of liquid corresponding to a predetermined positive pressure level at which the valve will open, while the internal passage is sized to hold a level of liquid corresponding to a predetermined negative pressure level at which the valve will open. At either the predetermined positive or negative pressure level, the valve opens when sufficient liquid has exited either the external or internal passage to permit the flow of a restrained gas past the liquid column.
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