What is a Pressure Switch? Understanding How Pressure Switches Work

content scma - February 27, 2025

A Pressure Switch, or pressure switch, is a widely used control device in industrial systems and general applications. It functions to detect and respond to changes in system pressure.Control equipment such as this plays a crucial role, from basic operation principles to types and appropriate selection for use.

What is a Pressure Switch?

A pressure switch is an intelligent control device that operates by detecting changes in pressure and automatically opening or closing electrical circuits when the predetermined pressure level is reached.

Unlike general pressure measurement tools such as pressure gauges or pressure sensors, which merely measure and monitor pressure levels, a pressure switch is more complex. It can use detected pressure values to automatically and accurately control various system operations.

What does a Pressure Switch do? Why is it important?

Pressure Switch functions to automatically turn equipment on and off when pressure exceeds or falls below predetermined levels, commonly used in pneumatic and hydraulic systems to control the operation of compressors, pumps, and other pressure control devices. In addition to enhancing operational efficiency, it increases system safety by preventing damage from abnormal pressures, extending equipment lifespan, reducing maintenance costs, and saving energy by operating only when necessary.

How a Pressure Switch Works

A Pressure Switch operates using pressure-sensing components (diaphragms or push mechanisms to convert into electrical energy) that change shape when the pressure changes. When the pressure reaches a predetermined level, the mechanism activates and opens or closes an electrical contact circuit. This status change sends control signals to various devices such as water pump switches, motors, valves, or alarm systems, allowing automatic system operation according to desired pressure levels.

2 Types of Pressure Switches

A Pressure Switch consists of a pressure sensing element and an electric switch that activates when the set point (preset value) is reached. The set point can be adjusted as needed. Selecting a switch with an appropriate pressure range is crucial for accuracy and longevity. There are two main types of Pressure Switches:

Electromechanical Pressure Switch

An Electromechanical Pressure Switch uses the mechanical movement of a sensing element to control a snap-action electric switch. It is further categorized into subtypes based on pressure-sensing mechanisms:

Differential Pressure Switches: These have two pressure ports (high/low) and operate from the difference in pressure. They are used to detect pressure differences between two points in a system, suitable for monitoring filter clogging or flow in a system.
Diaphragm Switches: These use interconnected metal diaphragms. When pressure increases, the diaphragm moves to trigger the switch. They are highly sensitive to changes in pressure and suitable for low to medium-pressure systems.
Diaphragm Piston Switches: These combine a rubber diaphragm with a piston. The diaphragm moves according to pressure and transmits force through the piston to trigger the switch. They are highly accurate and resistant to overpressure, suitable for high-precision work.
Bourdon Tube Switches: These use a curved Bourdon tube that tries to straighten when pressure increases, causing the end of the tube to move and trigger the switch. They are highly durable and suitable for high-pressure systems and harsh environments.
Piston Switches: These use a piston directly to control the switch. When pressure increases, it pushes against a spring until the switch is triggered. They are resistant to high pressure and impact, suitable for heavy-duty work in harsh conditions.

Solid State Pressure Switch

These use more advanced electronic technology with various functions such as digital displays, analog and digital outputs. They can be programmed and connected to PLCs or computers. They are highly durable, accurate up to ±0.25%, and have a longer lifespan than Electromechanical types.

Selecting a Pressure Switch

Selecting the appropriate pressure switch for your application requires considering multiple factors to achieve maximum efficiency and safety. You should take into account the nature of the work, environmental conditions, and technical specifications of the system being used.

Pressure Range Ensure that the pressure switch can accommodate the required pressure range without exceeding its operational limits.
Accuracy and Repeatability Consider the level of accuracy and repeatability needed for precise pressure control.
Environmental Conditions Evaluate the working environment, including temperature, humidity, vibration, and potential exposure to chemicals or contaminants, to select a pressure switch with appropriate environmental ratings.
Electrical Requirements Check for electrical compatibility and power requirements to ensure smooth operation with existing systems.

Want to Install a Pressure Switch? Consult SCMA for Advice

If you are looking for a high-quality and suitable Pressure Switch for your application, SCMA is a reliable choice. We have a team of experts ready to provide consultation and recommend products that meet your needs.

SCMA offers comprehensive services including:

Consultation on selecting the right Pressure Switch
Sales of high-quality products from leading brands
After-sales service and maintenance

Contact SCMA today to receive consultation and offers tailored to your needs.

Summary

A Pressure Switch is an important control device in various industrial systems, responsible for detecting pressure changes and automatically controlling system operations.

Currently, Pressure Switches are available in both Electromechanical types that rely on mechanical mechanisms and Solid state types that use modern electronic technology. Each type has its own advantages and suitability for different applications.

Choosing the right Pressure Switch involves considering multiple factors such as pressure range, accuracy, fluid compatibility, and environmental conditions to achieve optimal performance and safety during operation.

For additional advice or installation of a Pressure Switch for your system, you can contact SCMA. We are happy to provide consultation and services that meet your needs.