| 摘要 |
The present invention includes a ventilator for use in equalizing pressures within and without an enclosure, such as a coldroom or the like. A heated valve assembly is situated within an enclosure wall opening such that it is freely exposed to both environmental and internal fluid air pressures. A fluid impervious wall formed with inlet and outlet ports therethrough is partially covered by inner and outer closure members, both of which are supported and keyed by a common rod or shaft. These closure members are each biased by a common helical spring toward sealed and closed positions in which the inlet and outlet ports are covered. Pressure differentials are equalized by displacement of at least one of said closure members, thereby permitting air flow through one of the respective ports. By preselecting the spring rate of the helical spring, the minimum forces required to displace the closure members are controlled and predetermined.
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