A culture module is contemplated that allows the perfusion and optionally mechanical actuation of one or more microfluidic devices, such as organ-on-a-chip microfluidic devices comprising cells that mimic at least one function of an organ in the body. A method for pressure control is contemplated to allow the control of flow rate (while perfusing cells) despite limitations of common pressure regulators. The method for pressure control allows for perfusion of a microfluidic device, such as an organ on a chip microfluidic device comprising cells that mimic cells in an organ in the body, that is detachably linked with said assembly, so that fluid enters ports of the microfluidic device from a fluid reservoir, optionally without tubing, at a controllable flow rate.