Abstract: The valve includes a perforated cage and a perforated closed end tube operating as two sequential stages of restriction and pressure drop for the fluid flowing through the valve. A movable plug cooperates with the cage to control the net amount of flow restriction presented to the fluid, and hence to control the pressure drop across the valve and the rate of fluid flow through the valve. The tube perforations are sized to turn back the practical maximum of the first stage noise into the tube, and the latter is lined with material which absorbs a maximum of the turned-back noise. As a result, the level of the noise passing downstream of the valve is minimized.

Abstract: A differential pressure to electrical signal transmitter has a pair of flat barrier diaphragms and a central control diaphragm located between the barrier diaphragms. First chambers between one of the barrier diaphragms and the control diaphragm, and a first length of capillary tubing connected between the first chambers and one chamber of a remotely located sensor capsule, are filled with a first incompressible fill liquid. Second chambers between the other barrier diaphragm and the control diaphragm, and a second length of capillary tubing connected between the second chambers and another chamber of the sensor capsule, are filled with a second incompressible fill liquid. The fill liquids are made to pump up their respective flat barrier diaphragms to cause the latter to have a dome shape and hence to be free from "oil canning." A chamber on the outside of one barrier diaphragm is pressurized with a first fluid, and a chamber on the outside of the other barrier diaphragm is pressurized with a second fluid.