Air pressure regulators control the pressure in air lines used by pneumatic tools and machines. To provide consistent pressures, they remove fluctuations in the air supply and are adjustable. Some air pressure regulators attach to devices such as gauges, filters, lubricators, and displays.
There are several types of air pressure regulators. General purpose regulators are designed for typical industrial use and operate above atmospheric pressure. High pressure regulators are rated for inlet pressures over 1000 psi, and low pressure regulators operate at pressures below 15 20 psi. With dual stage regulators, fluid flows through successive chambers so that a constant pressure is delivered even when the inlet pressure decreases. Point-of-use regulators attach at or near a tool or device.
Air pressure regulators provide several methods of adjustment control. Manual regulators typically use knobs or T-handles. Analog voltage controls cover ranges such as 0 5V and 0 10V, while analog current controls are designed for current loops such as 4 20mA. Pneumatic adjustment controls or "volume boosters" control air inputs. Some adjustment controls include serial, parallel, or digital interfaces.
There are several ways to mount air pressure regulators. Cartridge-mounted regulators insert, screw in, or slip into place so that operators may remove them and gain access to valve components. Multiple valve modules stack into an assembly and contain integral circuit flow paths to reduce system piping. Other air pressure regulators use in-line (pipe), surface, subplate, or manifold mounting. In terms of connectors, National Pipe Thread (NPT) measurements range from 1/8" NPT to 2" NPT. Connectors may also use measurement standards such as British Standard Pipe Thread and Metric Pipe Thread.
Air pressure regulators use several types of body materials. Acetal polymers offer excellent inherent lubricity and provide both fatigue resistance and chemical resistance. Aluminum is resistant to oxidation and has good electrical and thermal conductivity. Brass also provides good conductivity, as well as excellent high temperature ductility and reasonable cold ductility. Cast iron is composed primarily of iron, but also has important trace amounts of carbon and silicon. Steel, a commercial iron that contains carbon as an essential alloying constituent, has less carbon than cast iron and is malleable. Stainless steel is chemical and corrosion resistant and is rated for high pressures. Zinc, a crystalline metallic element, becomes ductile with slight heating but is brittle at ordinary temperatures.
Some air pressure regulators are equipped with an internal pressure gage or a bleed-off valve for pressure relief. Others have an integral filter for fluid intake or an attached lubricator for valve operation. Tamper-proof air pressure regulators have security devices such as locks to prevent unwanted adjustment.