A mechanical pressure switch is a device used to monitor and control the pressure of a fluid or gas in various applications. It operates based on the mechanical movement of internal components when exposed to changes in pressure. When the pressure reaches a predetermined set point, the switch’s internal mechanism triggers an electrical contact or circuit, either closing or opening it. This change in the electrical state can be used to activate or deactivate pumps, motors, alarms, or other equipment, depending on the intended application. They are commonly used in various industries, including manufacturing, automotive, HVAC (heating, ventilation, and air conditioning), and more, to ensure the safety and control of system pressure levels.
Mechanical Pressure Switch Working Principle
Mechanical pressure switches in the compact design ensure safe pressure monitoring in, for example, pumps, compressors, and mobile working machines. Regardless of the application, they function by the principle of the preloaded spring, with a diaphragm or a piston as the measuring element.
With this functional principle, two forces act:
- The process pressure
It causes the pressure switch’s measuring part to respond. As a result, the instruments are designed in two ways. Therefore, at low process pressures, mechanical pressure switches have a diaphragm (due to the large surface area absorbing the pressure), while at higher pressures they have a piston with a small surface area.
- The force of the preloaded spring
This is adjusted using the pressure switch’s adjustment screw. The greater the power of the spring that the measuring element must withstand, the further the screw is turned in. This is accompanied by an increase in the value of the switch point. The spring geometry is designed based on the required switching range. By the functional principle of the mechanical pressure switch, the switch point is defined by the degree of spring preload. It is set as the pressure increases and the reset point is set accordingly as the pressure decreases.Factors Be Considered When Choosing a Setting Range?
What Factors Should Be Considered When Choosing A Mechanical Pressure Switch
When selecting the setting range for a mechanical pressure switch, several essential factors must be considered:
- Operating conditions: Consider the specific conditions under which the switch will operate, including temperature, pressure, and the nature of the fluid or gas. Ensure that the selected range is compatible with these conditions.
- System requirements: Understand the pressure requirements of the system and the desired set points for activating or deactivating the switch. The switch’s setting range should align with these requirements.
- Safety margins: It’s essential to include safety margins in the setting range to prevent pressure-related issues or damage to the system. A reasonable buffer should be added to the set point to account for variations and fluctuations.
- Overpressure protection: Consider the possibility of overpressure events and ensure that the selected setting range can handle such situations without causing damage or safety hazards.
- Accuracy and precision: Evaluate the required precision of pressure control in the system. Ensure that the switch’s setting range provides the necessary level of accuracy for the application.
- Response time: The setting range should allow the switch to respond quickly to pressure changes, especially if rapid response is crucial for the system’s safe and efficient operation.
- Regulatory compliance: Depending on the industry and application, there may be specific regulations and standards that dictate the permissible pressure range. Ensure that the chosen range complies with these requirements.
- Future adjustments: Consider whether the system may require adjustments to the pressure settings. Choose a setting range that allows for flexibility in case modifications are needed.
- Compatibility with the switch: Ensure that the selected setting range is within the capabilities of the specific mechanical pressure switch. Different switches may have different allowable ranges.
Advantages of Mechanical Pressure Switch
- Simple and reliable.
- Wide operating temperature range.
- Suitable for high-pressure applications.
- Long-lasting durability.
- Low power consumption.
- Easily adjustable set points.
- Can handle overpressure conditions.
- No external power source is required.
- Quick response time.
Disadvantages of Mechanical Pressure Switch
- Limited precision.
- Susceptible to wear and tear.
- Not ideal for remote monitoring.
- May require maintenance.
- Limited flexibility in set point adjustment.
- Limited features compared to electronic switches.
- Prone to hysteresis.
- Less suited for complex control systems.
- Can be affected by vibration.
- Limited compatibility with digital interfaces.
Applications of Mechanical Pressure Switch
- HVAC systems: Mechanical pressure switches are used to monitor refrigerant pressure in air conditioning and refrigeration systems, helping to maintain proper operating conditions.
- Industrial machinery: They manufacture equipment to ensure safe pressure levels and control various processes.
- Hydraulic systems: Mechanical pressure switches to monitor and control hydraulic pressure in machinery and heavy equipment.
- Water and sewage systems: They help maintain optimal pressure in water supply and sewage systems, preventing damage or inefficiencies.
- Boiler systems: These switches regulate pressure in boilers, ensuring safety and efficient operation.
- Automotive applications: Mechanical pressure switches can be found in automotive engines to monitor oil pressure, coolant pressure, and other critical parameters.
- Safety devices: They are used in fire suppression systems to trigger alarms and shut off valves in case of pressure irregularities.
- Pneumatic systems: Mechanical pressure switches are employed in pneumatic equipment to control and monitor air pressure.
- Compressors: They help regulate pressure in air compressors, ensuring proper functioning and preventing overpressure.
- Refrigeration equipment: Mechanical pressure switches are used in commercial refrigeration systems to control the compressor and maintain the desired temperature.