Pressure Switch
A pressure switch is a control component that converts pressure signals into electrical signals. It is widely used in hydraulic and pneumatic systems to detect, monitor, and control pressure changes. When the system pressure reaches a preset value, the pressure switch activates or deactivates electrical contacts to output a control signal. This signal can then drive other electrical components—such as solenoid valves, motors, time relays, or electromagnetic clutches—enabling functions like equipment start/stop, direction switching, pressure relief control, or safety protection.
Pressure switch offered by KUHNWAY
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Oil Pressure Switch
KUHNWAY offers high-performance hydraulic pressure switches that promptly transmit electrical signals when the system pressure reaches a preset value. These signals can be used to control devices such as solenoid valves, directional valves, or motors, enabling pressure protection and logic switching control within the system.
Features:
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High sensitivity, stable operation, and long service life
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Equipped with imported high-quality micro switches for superior accuracy and reliability
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Supports SPDT (Single-Pole Double-Throw) contact configuration to meet diverse control requirements
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Available with various installation thread options (e.g., 1/4" PT, NPT, BSP)
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Covers a wide range of pressure settings to suit different system needs
Applications:
Hydraulic machinery, automation equipment, machining centers, hydraulic pump control, and other industrial systems.
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Mechanical Pressure Switch
KUHNWAY is a professional distributor of the Korea-made HS series and a seller of the KHS series pressure switches. These series are known for their high stability and durability, making them particularly suitable for long-term operation and frequent actuation.
Product Features:
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Simple and stable mechanical design, operates without the need for a power supply
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Easy to adjust: pressure sensing range set via screw adjustment
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Multiple selectable pressure ranges and contact configurations available
Widely Used In:
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Fire protection systems
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Pneumatic and hydraulic pressure control
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Factory automation pipeline pressure management
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Pump start/stop control and overpressure protection systems
Types of pressure switches
Pressure switches can be classified into the following types based on their sensing method, output form, and application scenarios:
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Mechanical Pressure Switch
Operates by using a spring or diaphragm structure to detect pressure changes. When the pressure reaches the preset value, it triggers the switch mechanism. It features a simple design, low cost, and high durability, making it commonly used in booster pumps, air compressors, and general industrial applications. It can also be used in medium- and low-pressure steam systems, but models with high-temperature and condensation-resistant designs should be selected.
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Electronic Pressure Switch
Combines pressure sensors with microprocessor circuits to precisely measure and set pressure points. It supports digital displays, multi-stage control, and remote monitoring. Ideal for automation equipment, pneumatic systems, and high-precision process control.
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Liquid Pressure Switch
A pressure control component designed for hydraulic systems, capable of accurately monitoring liquid pressure and outputting switch signals based on preset values. Suitable for high-pressure and heavy-load environments such as hydraulic pumps, cylinders, molding machines, and various heavy industrial equipment. Liquid pressure switches enhance system stability and safety and are key components in hydraulic control.
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Gas Pressure Switch
Used to detect the pressure of air or other non-corrosive gases, commonly found in compressed air systems, refrigerant control, and pneumatic tools. Also suitable for pressure control and monitoring of gases like city gas, natural gas, and liquefied petroleum gas.
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Explosion-Proof Pressure Switch
Designed for hazardous environments such as petrochemical plants, gas pipelines, and mining areas. These switches feature spark-proof mechanisms, explosion-proof enclosures, and high sealing capability to ensure the safety of personnel and equipment.
Structure of a Pressure Switch
While the design of a pressure switch may vary depending on the model and application, it generally consists of the following main components:
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Housing
Encloses the pressure switch body to protect internal components from external elements such as dust, moisture, oil, or mechanical impact. Depending on the operating environment, special housings may be selected for waterproofing, explosion-proofing, or high-temperature resistance.
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Body
The core structure that supports all internal components, including sensing elements, actuation mechanisms, and contact devices. Typically made of metal (such as aluminum alloy or stainless steel) or high-strength engineering plastic to ensure durability and mechanical stability.
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Sensing Element / Pressure Port
This is the point of contact with the measured medium (liquid or gas) and serves as the inlet for pressure transmission. Depending on application requirements, sensing elements may be diaphragms, pistons, or Bourdon tubes, and materials must be pressure-resistant and corrosion-resistant.
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Electrical Circuit / PCB
Commonly found in electronic pressure switches, it converts detected pressure signals into digital or analog electrical signals to drive the switch or send output to PLCs and other control systems. High-end models may also include modules for display, delay functions, and user setting interfaces.
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Actuation Mechanism
The transmission structure between the pressure-sensing element and the switch contacts. It drives contact movement in response to pressure changes. Mechanical switches typically use spring-loaded mechanisms, while electronic types are controlled by microcontrollers using relays or semiconductor switching components.
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Power & Terminal Connections
Provides connections for external power and control circuits. Terminal types include screw terminals, quick-connect terminals, or waterproof connectors. Some models support M12 or DIN standard plugs for enhanced installation convenience and safety.
Pressure Switch Contact Types
The “contact type” of a pressure switch refers to the configuration and behavior of its internal electrical contacts when energized or de-energized. This determines how the switch controls a circuit. Common contact types include:
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SPST (Single Pole Single Throw)
The most basic type of contact, designed to control a single circuit with a simple on/off function. It includes one input terminal and one output terminal, providing a binary operation: either connected (ON) or disconnected (OFF).
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Application: Used for simple start/stop control applications such as pump switching or alarm triggering.
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Forms:
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NO (Normally Open): Circuit is open in the default state; closes (conducts) when the pressure reaches the set point.
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NC (Normally Closed): Circuit is closed in the default state; opens (disconnects) when the pressure reaches the set point.
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SPDT (Single Pole Double Throw)
Controls a single input circuit but provides two output paths, allowing the signal to switch between them depending on the pressure. Functions like a fork in the road, directing the input signal to either of two outputs.
Typical structure includes three terminals: one Common (COM), one Normally Open (NO), and one Normally Closed (NC). As pressure changes, the switch toggles between NO and NC.
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Application: Suitable for dual-function control—e.g., activating a motor while simultaneously deactivating an indicator light—or for alarm and action switching.
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Features: Versatile functionality; widely used in industrial applications.
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DPDT (Double Pole Double Throw)
Essentially two SPDT switches mechanically linked and operated by a single actuator. It has two independent input circuits (double pole), each capable of switching between two outputs (double throw). Typically includes six terminals: two COM, two NO, and two NC.
When activated, both circuits switch simultaneously, allowing synchronized control of two independent systems.
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Application: Ideal for complex or redundant control systems, such as dual-loop safety protection or alternating dual-pump systems.
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Features: Larger and more costly; typically found in high-end electronic pressure switches or specialized industrial equipment.
Considerations When Selecting a Pressure Switch
When selecting a pressure switch, it is important to consider the system's operational requirements and environmental conditions to ensure long-term reliability and stability. Key points include:
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Pressure Range
Ensure the pressure switch's setting range covers the system's normal operating pressure. It is generally recommended to select a range slightly higher than the actual working pressure to prevent frequent switching, and the maximum pressure rating should exceed potential pressure peaks to avoid overload or damage.
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Accuracy
Mechanical pressure switches use springs or diaphragms as sensing elements and operate via mechanical linkage. Due to limitations such as elastic fatigue, friction, and manufacturing tolerances, their accuracy is typically ±2% to ±5% FS. Advantages include simplicity, durability, and no power requirement.
Electronic pressure switches integrate high-precision sensors with microprocessor circuits for digital setting and stable output, with accuracy reaching ±0.5% to ±1% FS or better. Suitable for precision control and multi-stage logic.
Select accuracy level based on system control requirements—higher accuracy improves control precision and system stability.
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Repeatability
Repeatability refers to how consistently the switch activates at the same pressure under identical conditions. In systems with frequent pressure fluctuations, stable repeatability is essential for reliable operation.
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Accuracy = “How precise”
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Repeatability = “How consistent”
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Hysteresis
Hysteresis is the pressure difference between switch-on and switch-off points. The switch will not reset immediately as pressure drops, but only when it falls below a certain threshold. This helps prevent frequent switching caused by minor pressure fluctuations.
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Response Time & Switching Frequency
Response time is the delay from pressure change to signal output—important in high-frequency or real-time control.
Switching frequency is the number of on/off cycles the switch can endure per second or minute. Mechanical types support lower rates; electronic types support higher ones.
In high-duty applications like test benches, air compressors, or packaging lines, select switches designed for high durability and cycle life.
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Sensing Type
Choose between mechanical (spring/diaphragm) and electronic (sensor + processor) types based on precision, response time, and system requirements.
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Media Compatibility
Ensure the switch materials are compatible with the fluid used (e.g., air, water, oil, refrigerants) to prevent corrosion or failure.
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Electrical Specifications
Verify voltage, current rating, and contact capacity to ensure compatibility with the control circuit and connected devices.
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Protection Rating
Select a pressure switch with appropriate IP or explosion-proof rating for use in outdoor, high-humidity, dusty, or hazardous environments (e.g., IP65, Ex d).
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Compliance & Certification
Ensure the product meets required standards such as CE, UL, or RoHS for safety and export compliance.
Applications of Pressure Switches
Pressure switches play a vital role in industrial control and equipment protection, primarily enabling the following functions:
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Pressure Sensing
When the system pressure reaches a preset threshold, the pressure switch instantly sends an electrical signal to trigger a response—such as turning on a warning light, starting a pump, or sending a control signal to a PLC. This function is commonly used in pressure monitoring stations, HVAC systems, and pneumatic setups.
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Pressure Regulation
Pressure switches can control the start and stop of pumps, solenoid valves, or compressors. They automatically regulate system pressure when it exceeds or falls below the preset range, ensuring operation within safe limits. For example, in a booster pump system, a pressure switch automatically turns the pump on or off to maintain stable water pressure.
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System Protection
In the event of abnormal pressure—too high or too low—the pressure switch can immediately cut off the power circuit, activate protective relays, or trigger alarm systems. This prevents equipment overload, leaks, or damage. Commonly used in hydraulic systems, boilers, and high-pressure pipelines.
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Process Automation
Pressure switches can execute specific control logic based on pressure stages, such as starting/stopping motors, switching valve directions, or changing production processes. Widely applied in automated production lines, food processing, packaging machines, and filling systems.
Globally Renowned Pressure Switch Brands
In industrial automation and fluid control systems, choosing a reliable pressure switch brand is critical for ensuring system stability and safety. Below are some of the most trusted global leaders in pressure switch manufacturing:
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Honeywell (USA)
Renowned for its high precision and reliability, Honeywell pressure switches are widely used in industrial automation, HVAC, medical devices, and energy systems. The products feature rugged construction, excellent vibration resistance, and long service life. Honeywell offers a full range of mechanical and advanced electronic pressure switches suitable for gas, liquid, and vacuum environments, meeting the demands of precision control and safety protection.
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Schneider Electric (France)
A global leader in power and automation solutions, Schneider Electric’s pressure switches are known for their durability and stable performance. They are commonly used in building management, electrical systems, machinery protection, and pump control applications.
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Emerson (USA)
Through its sub-brands such as ASCO and TESCOM, Emerson provides high-precision pressure switches widely used in process industries, gas control, chemical processing, and energy sectors. Known for exceptional reliability and suitability for harsh environments.
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Siemens (Germany)
Famous for innovation and German engineering, Siemens offers a wide range of pressure switches and sensors designed for smart factories, automated production lines, and energy management systems. Many models support various communication protocols for seamless integration.
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Danfoss (Denmark)
Specializing in pressure and temperature control, Danfoss products are known for their durability, long service life, and high adjustability. Their pressure switches cover applications from vacuum to high pressure. The KP series is commonly used in refrigeration and HVAC systems, while the RT series is suitable for high-pressure industrial and hydraulic applications.
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Saginomiya Seisakusho (Japan)
A well-established Japanese manufacturer with over 70 years of experience in automatic control components. Saginomiya is known for its precise design, high stability, and long product life. Their pressure switches are widely used in refrigeration, pneumatic systems, and fluid control across global OEM equipment and critical systems.
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Festo (Germany)
A leader in automation technology and pneumatic components, Festo offers high-performance electronic and pneumatic pressure switches. Ideal for robotics, Industry 4.0 applications, and automated assembly lines, Festo’s products support IO-Link and digital output, providing excellent integration and accuracy.
Application of Excel Pressure Switch in Automatic Alarm Check Valve Systems
The automatic alarm check valve (also known as a waterflow detection device) is a critical component in wet-type automatic sprinkler fire suppression systems. Its primary functions are to monitor water flow and trigger the alarm system, while simultaneously controlling flow direction to prevent backflow, which could cause system malfunctions or water source contamination.
In this system, the pressure switch plays a central role in monitoring and triggering. When a fire occurs and the sprinkler head is activated, water begins to flow through the piping, causing a pressure drop on the discharge side and creating a pressure differential. The pressure switch detects this change in real-time and, once the pressure exceeds a preset threshold, it sends out an electrical signal to activate audible and visual alarms or notify the central control system—prompting an immediate response from on-site personnel.
In addition, the pressure switch can assist in controlling the opening and closing of the check valve, ensuring that water flows only from the supply side to the sprinkler heads, preventing backflow and maintaining hygiene in the pipeline. This combined application enables comprehensive pressure monitoring, automatic alarm triggering, and water flow control, significantly enhancing the safety and automation level of the entire fire protection system.