Abstract: A safety guard or lockout device (22) for a dual chamber orifice fitting device (1) having a removable orifice plate (4). In a normal position when the upper and lower chambers (8, 9) are equal in pressure, the guard (50) of the safety guard device (22) is in a retracted position relative to the square end (36) of a valve gear shaft (18) as shown in FIG. 3 to permit connection of a manual tool, such as a wrench, to square end (36) of valve gear shaft (18) for actuation of isolation valve member (16). When changing the orifice plate (4), the pressure in the upper chamber (8) is reduced to atmospheric conditions and provides a fluid pressure differential between chambers (8) and (9). The fluid pressure differential moves fluid responsive member (30) and guard (50) to an extended position covering the square end (36) of valve gear shaft (18) to prevent access of a manual tool to the shaft (18) thereby preventing operation of the isolation valve (16) separating the upper chamber (8) from the lower chamber (9).

Abstract: An orifice fitting with an orifice plate centered in the flow passage of an orifice fitting via direct contact between a cradle and the orifice plate. The orifice plate is centered via the use of an orifice plate carrier having two channels on its downstream side and two slots located in the bottom portion of the seat, which is located on the plate carrier's upstream side. The plate fits into the seat and a bottom portion of the plate's peripheral edge protrudes through the slots. A cradle having locating surfaces fits through the channels in the orifice plate carrier and firmly holds the orifice plate against the orifice plate carrier. The cradle can be positioned and then secured in place by two adjustable set screws and a stem piece of the cradle. Once the orifice plate has been centered via the positioning of the cradle, the stem piece of the cradle and the set screws can be welded into the body of the orifice fitting.