The regulator connects to a high pressure fluid supply and regulates the pressure to a downstream apparatus. If an over-pressure occurs, it is vented to atmosphere. An elongate control stem engages a supply seal assembly and a vent seal assembly and moves axially with respect to these seal assemblies to achieve regulation and venting. During high fluid flow, the supply seal assembly and the vent seal assembly are not in the fluid flow path of the regulator which makes the seal assemblies more resistant to erosion from fluid flow. The fluid flow path through the regulator is partially in hollow passageways in the elongate control stem.