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:
Nov. 19, 1991
Filed:
Aug. 15, 1989
John P Angelosanto, North Attleboro, MA (US);
George E Sgourakes, Millis, MA (US);
The Foxboro Company, Foxboro, MA (US);
Abstract
A differential pressure measuring system comprising a transmitter for a pressure-measuring instrument connected to a control room by a two-wire transmission line carrying a d-c signal powered from the control room and representing the measured pressure. The instrument includes a reference pressure device of the falling-ball type, wherein a ball is first lifted to an upper position and then allowed to descend under the force of gravity to produce a reference pressure pulse for calibrating the instrument span. The lifting device for the ball is a two-coil magnetic actuator powered by current from the two-wire transmission line, and is operable at a sufficiently low current to be classified intrinsically safe. The reference pressure device is supported by an adjustable mounting providing two degrees of freedom for movement so as to permit ready adjustment of the device orientation to assure alignment with the force of gravity.