Dwyer Instruments, Inc.

Sor Inc.

John M Donnelly

Stephen S Clark

Prabhaharan Kumarakulasingam

Xiqing Ma

Arthur David Womack, Jr

Mark Stephen Bartrum

A process control instruments includes a sensor for sensing a process variable in a processing environment, and a switch, a gauge, and a transmitter. The sensor, switch, gauge, and transmitter, a controller to which each of the stated and related components are connected, are powered via a two-wire power loop. In particular, the two-wired power loop also comprises the transmitter, such that the controller, upon receiving information indicative of the level of a variable being sensed by the sensor, modulates the amplitude of the current on the two-wire loop to a level corresponding to the level of the processed variables sensed. Each of the switch, gauge, and transmitter are independently scalable. In the preferred embodiment of the invention, a pair of switches in the form of relays are provided, and a logic circuit operates to power the components of the invention, with the exception of the relays, when the process variable being sensed with within a selected range. When, however, the process variable being sensed dips below the lower threshold(s) or rises above an upper threshold(s), the logic circuit operates to provide power to the components of the invention through a relay corresponding to the threshold reached.

Process control instrument with multiple functions

A differential pressure switch assembly that includes a conventional snap action switch for controlling the off-on modes of operation of state of the art equipment, which assembly comprises a high pressure plate that defines the high pressure cavity and a high pressure port of restricted size therefor, a low pressure plate that defines a first subchamber of the assembly low pressure cavity and a low pressure port therefor, a diaphragm clamped between the high and low pressure plates and separating the switch assembly high and low pressure cavities, a piston mounted in the low pressure plate for movement perpendicularly of the assembly diaphragm and biased toward the diaphragm by an adjustable range spring device, the range spring of which can be adjusted to provide the set point for the switch assembly, with the range spring device being formed to dispose the range spring in a second low pressure subchamber that is in open communication with the first low pressure subchamber to form a composite low pressure chamber, and with the low pressure plate journaling a rotary take out shaft that is coupled to the piston within the low pressure composite chamber and actuates a mechanical mechanism for utilizing the diaphragm motion for a particular set point of a switch assembly to actuate the snap action switch of same free of high deadband.

Differential pressure switch assembly with high static pressure use

Growing community of inventors

Overland Park, KS, United States of America

John M Donnelly