A regulator is loosely any device in an automated system which maintains a particular designated characteristic, by managing a range of predetermined values in a piece of machinery. These values can be programmed or dictated by specific operating conditions, and can be used to control light, speed, power or flow rates. Common examples include fuel and voltage regulators and pressure regulators.
Air regulators, or pressure-reducing valves, are used in compressed air systems to maintain a constant output pressure, whatever fluctuations may occur in the input pressure or the output flow. A typical example of this is in scuba diving equipment, where the supply pressure is reduced to the required level for breathing. In industrial systems, a regulator governs the level of pressure required to run downstream pneumatic equipment most efficiently.
Regulators can sense downstream pressure by means of either a diaphragm or piston that reacts to pressure changes, and a spring-operated valve to control the flow. They can be of simple or complex design, depending on what type of application they will be used for, and its performance requirements. Piston actuated regulators are usually more robust and offer a proportionately larger area of effective pressure sensing, while diaphragms react faster to pressure changes and are commonly more sensitive.
Regulator selection is influenced by several important factors, including pipe sizes, flow rates, maximum and minimum regulated pressure requirements, ease and frequency of adjustment, and normal line pressure. For safety purposes, some means of shut-off valve or controlled venting should be incorporated.