Abstract: An improved adjustable fluid flow regulator having a regulator chamber, a moveable diaphragm within the regulator chamber, a spring that acts upon the diaphragm to regulate the flow of fluid, and a first adjustment member and second adjustment member for adjustably biasing the spring against the diaphragm. The improvement includes a tamper resistant feature for restricting adjustment above a predetermined limit. The first adjustment member is fully adjusted to a limit. The second adjustment member is adjusted to bias the spring to a predetermined maximum setting, and restricted from further adjustment. The first adjustment member would subsequently be adjustable to any setting up to the predetermined limit.