Balanced plug assemblies and pressure regulators having balanced plug assemblies

A plug assembly for a pressure regulator, the plug assembly comprising:

• a stem having a stem body and a flange extending radially from the stem body;
• a plug coupled to the stem body, the plug to be moved relative to a seat in the pressure regulator to control a flow of fluid through the seat;
• and
• a stem guide to be disposed in the pressure regulator between a fluid passageway and a pressure sense chamber, the stem guide having a first side to face the pressure sense chamber and a second side to face the fluid passageway, the stem guide defining a balance chamber, the stem extending through the stem guide such that the flange is disposed in the balance chamber, the flange dividing the balance chamber into a first balance chamber portion and a second balance chamber portion, wherein a first balance passage is defined in the stem and the plug that fluidly couples the fluid passageway and the first balance chamber portion, and wherein a second balance passage is defined in the stem guide that fluidly couples the pressure sense chamber and the second balance chamber portion, the stem including a first stem guide body and a second stem guide body, the first stem guide body includes a first disc having a first side and a second side opposite the first side, the first stem guide body having a first collar extending from the first side of the first disc, the first disc having a groove along an outer peripheral edge of the first disc between the first side and the second side of the first disc, the groove forming at least a portion of the second balance passage.

A pressure regulator comprising:

• a device body defining a fluid passageway between an inlet and an outlet, the device body having a channel between the fluid passageway and a pressure sense chamber;
• a seat in the fluid passageway;
• a stem having a flange;
• a plug coupled to the stem, the stem being moveable to move the plug relative to the seat to control a flow of fluid between the inlet and the outlet;
• a stem guide disposed in the channel of the device body, the stem guide having a first side exposed to the fluid passageway and a second side exposed to the pressure sense chamber, the stem guide defining a balance chamber, the stem extending through the stem guide, the flange of the stem disposed in the balance chamber and dividing the balance chamber into a first balance chamber portion and a second balance chamber portion, wherein the stem and the stem guide are sealingly engaged such that the second balance chamber portion is fluidly isolated from the fluid passageway;
• means for fluidly coupling the fluid passageway and the first balance chamber portion;
• and
• means for fluidly coupling the pressure sense chamber and the second balance chamber portion.