Charles A Doherty

US Patent:

45647623, Jan 14, 1986

Filed:

May 16, 1984

Appl. No.:

6/610760

Inventors:

Charles F. Doherty - Quincy MA
Robert E. Johnson - Pembroke MA

Assignee:

Pyrotector, Inc. - Hingham MA

International Classification:

G01T 1185

US Classification:

250381

Abstract:

An ionization detector unit for use in a smoke detector includes a housing wall enclosing an ionization chamber, the wall having openings for passage of air through the chamber, the frontal surface of the wall that is exposed to an oncoming air flow from a given direction being inclined relative to an intersecting second surface exposed to the flow. The frontal surface is shaped and positioned to deflect the air flow generally toward the second surface, and the second surface is shaped and positioned to deflect the air flow generally toward the frontal surface, the shape and position of the surfaces cooperatively arranged to cause the deflected air flows to converge and form a region of air in the vicinity of the intersection of the surfaces that is at higher pressure and slower velocity than the oncoming air flow. Apertures are provided in the frontal surface of the housing to enable entry of air from the vicinity of the intersection to establish relatively slow, laminar air flow through the chamber, thereby to enable an effective ion current to be maintained within the chamber despite high velocity of oncoming air.

US Patent:

45298815, Jul 16, 1985

Filed:

Mar 2, 1982

Appl. No.:

6/353905

Inventors:

Thomas J. Ceurvels - Wollaston MA
Rashid A. Chaudhary - East Weymouth MA
Charles F. Doherty - Quincy MA

Assignee:

Pyrotector, Inc. - Hingham MA

International Classification:

G01J 504
G08B 1712

US Classification:

250353

Abstract:

A radiation detector for use in hazardous locations, comprising an explosion proof housing with a viewing window and a detector element positioned inside the housing to receive radiation through the viewing window, and means within the housing to apply test radiation onto the external face of the viewing window directly. In one embodiment of the invention the viewing window is recessed in a housing cavity with a flared wall and the test radiation is applied from a housing portion that extends forwardly of the plane of the viewing window. In a preferred embodiment of the invention the housing is formed of front and rear portions which are rotatable in relation to each other, and the viewing window is mounted in a surface of the front portion which is inclined at a 45. degree. angle to the axis of rotation of the portions, and the rear portion has mounting means enabling mounting of the detector so that it can rotate about an axis disposed at a 45. degree. angle to the axis of rotation of the portions, thereby allowing adjustment of the detector to view in any desired direction.