A pressure actuator is a device that triggers an action in response to building or decreasing pressure inside a cylinder. One example can be found inside a car, where a driver increases pressure in a brake system by stepping on the pedals, which operates the brakes and slows the vehicle. Pressure actuators can turn a small amount of work into significant energy, and they can also operate automatically, not just in response to a command from an operator. They are found in a wide variety of devices.
The device includes a piston inside a cylinder, with a pressure-sensitive diaphragm. With some designs, the pressure actuator stays open in a neutral state and needs pressure to close, while others work the other way around. Pressure changes move the piston up and down the cylinder, which moves a valve stem and activates systems connected to the device. This can be part of a hydraulic system, allowing for the amplification of energy to perform tasks like stopping a vehicle or lifting very heavy weights.
Some pressure actuators are filled with fluids, while others may use gases. In a system controlled by an operator, an action like stepping on a pedal or pressing a button changes the pressure and triggers operation of the pressure actuator. Other systems operate automatically. For instance, a sprinkler system in a building can respond to pressure changes caused by increased heat to open up the sprinklers and put out a fire with water, suppressant foam, or inert gases, depending on the setting.
When a pressure actuator is broken, it may not function correctly. The device could become stuck in the wrong position, or might not respond to pressure. Like other moving mechanical parts, pressure actuators need regular inspections to confirm they are in good working order and check for signs of problems like worn parts or damaged diaphragms. If a device does not work properly, a technician can replace it or a component to address the issue.
Size, location, and position of a pressure actuator can vary depending on the system. Mechanics are familiar with the workings of the systems they handle and they can usually adapt to similar systems to address problems with their pressure actuators. Sometimes it is necessary to take special precautions before starting work, like draining lines to relieve pressure before opening up a pressurized system. Warnings may be printed on the equipment as well as being listed in accompanying documentation in an effort to reduce the risk of accidents.