The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 31, 1995
Filed:
Jul. 02, 1993
Gordon P Sharp, Newton, MA (US);
Eric Desrochers, Nashua, NH (US);
Phoenix Controls Corporation, Newton, MA (US);
Abstract
A system for maintaining a desired pressure (either positive or negative with respect to surrounding) in a sealed room or other substantially sealed closed space has a gas supply and a gas exhaust connected to the space through a supply flow control element and an exhaust flow control element, respectively. A tracking one of the two control elements has its flow controlled in response both to the measured pressure in the space and to an indication of flow through the other, driving flow control element. The flow control elements are adapted to provide a designed, at least nominal effective leakage for the space with changes in the pressure differential between the space and at least one of the gas supply and gas exhaust. For preferred embodiments, the effective leakage is achieved by either mechanically or electronically modifying the flow/pressure characteristic of at least one of the valves to have a designed, at least nominal change in flow for changes in pressure across the element.