Patent ID: 8151822
Filing Date: 2012-04-10
Classification: F16K,G05D,Y10T

Abstract:
1. A monitoring device for a fluid flow regulating device having a valve body with an inlet, an outlet and a valve port, and an actuator with an actuator control element and an actuator control assembly for sensing and regulating a pressure downstream of the fluid flow regulating device to maintain the downstream pressure approximately equal to an actuator setpoint pressure, the monitoring device comprising: a monitor control element extending into the valve body and displaceable relative to the valve port for allowing and preventing the flow of a fluid between the inlet and the outlet, wherein the monitor control element is moveable between an open position wherein the monitor control element is disengaged from the valve port to allow fluid flow between the inlet and the outlet, and a closed position wherein the monitor control element engages the valve port to prevent fluid flow between the inlet and the outlet, and a diaphragm operatively connected to the monitor control element and having a plane perpendicular to the direction of fluid flow into the inlet and out of the outlet of the valve body, wherein a first side of the diaphragm is in fluid communication with the pressure downstream of the fluid flow regulating device and a second side of the diaphragm is biased against the force applied by the downstream pressure to the first side, wherein the diaphragm deflects to move the monitor control element to the closed position when the downstream pressure is greater than a monitor setpoint pressure, and wherein the monitor setpoint pressure is greater than the actuator setpoint pressure, wherein an upstream pressure within the valve body applies a force to the diaphragm to bias the monitor control element in the direction of the open position, and wherein the monitoring device comprises a balancing diaphragm having a first side engaging the monitor control element and a second side in fluid communication with the upstream pressure such that the balancing diaphragm applies a force to the monitor control element in the direction of the closed position; and further comprising an opening spring biasing the monitor control element toward the open position, and wherein the balancing diaphragm is configured so that the force applied by the balancing diaphragm is approximately equal to the force applied by the upstream pressure plus the biasing force applied by the opening spring.