Apparatus and methods for regulating negative pressure in a negative pressure wound therapy system

A pressure switch for controlling application of negative pressure to dressing disposed adjacent a tissue site is disclosed. The pressure switch comprises a body having a base, sidewalls extending from the base to an open end, and an inlet coupled to the dressing and forming a passage through the body. The pressure switch further comprises a diaphragm closing the open end of the sidewalls and forming a vacuum chamber with the body, wherein the inlet fluidly couples the vacuum chamber and the dressing. The pressure switch further comprises a valve disposed in the passage and configured to restrict the flow of gas through the passage so that a switch pressure developed in the vacuum chamber as a result of the application of negative pressure to the dressing lags a wound pressure at the tissue site to delay, wherein the diaphragm is adapted to be operatively responsive to the switch pressure to move between a relaxed position and a compressed position as the negative pressure increases and decreases. This pressure switch further comprises a switching element coupled to the diaphragm to turn on the negative pressure in the relaxed position and turn off the negative pressure in the compressed position. In another example, a method for controlling application of negative pressure to dressing disposed adjacent a tissue site using a pressure switch is disclosed. In another example, a system for applying negative pressure to a tissue site using a pressure switch is disclosed.