Pressure switches use fluid pressure to close off electrical contact when it reaches its input. Industries use pressure switches to control and supervise systems that require pressurized fluids to function.
Workers can adjust pressure switches by moving the contacts or adjusting the tension in the counterbalancing springs, and they can arrange the pressure-sensing elements of the switch to respond to differences between two pressures. Pressure switches can also make contact when pressure rises or falls.
Pressure Switch Types
Pressure switches exist in two basic forms: electromechanical pressure switches and solid-state pressure switches.
Electromechanical pressure switches use various types of sensors to operate. These sensors determine how accurate and how long the switches last, and come in forms including:
· Diaphragm switches: This switch uses a weld-sealed metal diaphragm that has an operating pressure of up to 150 psi and an accuracy of ±0.5%.
· Diaphragm piston switches: An elastic diaphragm works with a piston that then activates the switch. They can operate in vacuum conditions as well as pressures of up to 1,600 psi with an accuracy of ±0.2%.
· Piston switches: A piston directly activates the switch, which comes with an operating pressure of 12,000 psi and an accuracy of ±0.2%.
· Bourdon tube switches: This switch activates a weld-sealed bourdon tube, which has an operating pressure range of 50–18,000 psi within an accuracy of ±0.5%.
· Differential pressure switches: These switches have two pressure ports, one each for low and high process pressure. These ports detect pressure differences between the sources to actuate the switch. They can operate with a diaphragm or with metallic or elastomeric sensors.
Solid-state pressure switches can come with a range of switch points, or they can include just one, and they generally last longer compared with electromechanical pressure switches. Solid-state switches open and close the pressure switch circuit and provide output using digital displays. They work with a wide range of operating pressures and frequency responses that resist shock and vibration, and they function with accuracies of ±0.25%.
Many industries use pressure switches, especially industries that rely on automated equipment like press machines and plastic molding injectors, and pressure switches also appear in automotive applications like motor engine oil and transmissions. Modern electronic pressure switches use pressure sensors to continually collect data, and they limit values within the process using one or more mechanical switches while operating with only one pressure port.
Because electronic pressure switches simplify the control process, they often take the place of mechanical switches, especially in these applications:
· Replacing mechanical pressure switches mounted in pressure lines, allowing more control over the switch operations and local programming as well as providing a local LED display that helps with troubleshooting
· Maintaining better switch point performance when an application has various switching cycles
· Individually programming situations from switching operations
· Allowing users to see how the pressure in the machine trends over time when local indication is needed
· Allowing users to have more control of the switch point by preventing system oscillation
Although analog pressure transmitters can present core information, they come with expensive interfaces, especially when users need to monitor and control them. Electronic pressure switches work in the same way as analog pressure transmitters, but they operate in a more intelligent and cost-effective manner.
Switch Up Your Production Line with Endress + Hauser
Endress + Hauser provides a full range of pressure switches for a variety of applications. For more information about pressure switches and which would be best for you, contact us and request a free quote today.