Methods, systems, and devices are provided for controlling fluid flow in a pressure sensing system. A bi-directional valve can include a first capillary that can couple to a process fluid in a process fluid channel, and a second capillary that can couple to a pressure sensor. The first and second capillaries can include an interface therebetween for controlling fluid flow between the first and second capillaries. The interface region can be configured to allow fluid flow between the first and second capillaries when a magnitude of a pressure difference between the first capillary and the second capillary is less than or equal to a threshold pressure. The interface region can also be configured to prevent fluid flow between the first capillary and the second capillary when the magnitude of the pressure difference between the first capillary and the second capillary exceeds than the threshold pressure.