Examples disclosed herein relate to a cartridge including: a body with a first groove and a second groove, the body including a body inlet area and a body outlet area; an o-ring coupled to body via the first groove; a throttle pin coupled to the top retainer through the inlet area; a spring cap with a groove area; a spring cap o-ring coupled to the spring cap via the groove area; a spring coupled to a bottom retainer; a diaphragm coupled to the bottom retainer; and a top retainer coupled to the diaphragm.