The basic steps for selecting a vacuum pressure switch

The selection of vacuum pressure switches should be combined with the actual application scenarios and comprehensively considered from aspects such as parameter matching, environmental adaptability, and functional requirements. The following is a detailed description of its basic selection steps:

1. Clarify the application requirements

Determination of the measurement range

Select a switch with an appropriate range based on the system pressure range. For instance, if the vacuum degree range of the system is from -90 kpa to -10 kpa, a switch with a range covering this range (such as -100 kpa to 0kPa) should be selected to avoid a decrease in accuracy due to an excessive range.

Analogy: Choosing a thermometer with an overly large range to measure body temperature may lead to reading errors.

Action threshold setting

Determine the trigger pressure value of the switch (for example, start the vacuum pump at -80 kpa). The stability of the system should be taken into account, and an appropriate dead zone (such as ±5kPa) should be reserved to avoid frequent starts and stops.

Output signal type

Select the type of output signal according to the requirements of the control system:

Mechanical contacts: Suitable for direct control of relays or solenoid valves.

Electrical signal (4-20mA, 0-10V) : Suitable for PLC or DCS systems, facilitating remote monitoring.

In industrial automation, 4-20mA signals are often used to communicate with PLCS.

2. Confirm the environmental and medium conditions

Environmental temperature and humidity

High-temperature environments may cause the internal components of the switch to age. It is necessary to select a temperature-resistant model (such as an operating temperature range of -20℃ to 80℃). In high-humidity environments, the protection level (such as IP65) needs to be considered.

Medium characteristics

Corrosive medium: Corrosion-resistant materials (such as 316L stainless steel diaphragms) should be selected.

Viscous medium: Avoid using small holes to directly access the pressure port to prevent blockage.

The food industry may need to select materials that meet FDA standards.

Vibration and Shock

If it is installed in equipment with severe vibration (such as compressors), anti-vibration type switches should be selected or additional shock absorption measures should be added.

3. Determine the functional and performance requirements

Response speed

For rapid response scenarios (such as vacuum packaging machines), switches with short response times (such as ≤50ms) should be selected. For general applications, models with a response time of ≤200ms can be selected.

Accuracy and repeatability

For high-precision requirements (such as laboratory equipment), switches with an accuracy of ±1%FS should be selected. For general industrial applications, ±2%FS is sufficient.

Protection and Certification

Explosion-proof types (such as Ex d IIC T6) should be selected for explosive environments.

The exported equipment must comply with certifications such as CE and UL.

The chemical industry often requires ATEX explosion-proof certification.

4. Consider the convenience of installation and maintenance

Installation method

Select the appropriate structure based on the installation space:

Threaded connection: Suitable for small pipe diameter systems.

Flange connection: Suitable for large pipe diameters or high-pressure systems.

Comparison: Threaded connections are more compact, while flange connections are more stable.

Display and Debugging

The switch with digital display is convenient for on-site debugging. Models without display need to be calibrated by an external instrument.

Maintenance cost

Choose models with easily replaceable parts (such as diaphragms and contacts) to reduce long-term maintenance costs.

5. Verification and Testing

Prototype testing

Test the response time, accuracy and stability of the switch under simulated working conditions. For example, by simulating pressure changes through a pressure generator, observe whether the switch action meets expectations.

Compatibility verification

Confirm that the switch output signal is compatible with the control system to avoid misoperation caused by signal mismatch.

6. Cost and Supply Cycle

Evaluation of cost performance

Under the premise of meeting the performance requirements, select the model with reasonable cost. For example, domestic switches may offer better cost performance than imported models.

Supply cycle

For urgent projects, it is necessary to confirm the delivery time of suppliers to avoid project delays caused by stockouts.

Selection Summary

Core principle: Oriented towards application requirements, while taking into account performance, environmental adaptability and cost.

Key steps:

Determine the pressure range and action threshold.

Analyze the environmental and medium conditions.

Clarify the functional and performance requirements.

Consider the convenience of installation and maintenance.

Verify the prototype and compatibility.

Evaluate the cost and supply cycle.

Through the above steps, the selection of vacuum pressure switches can be systematically completed to ensure their stability and reliability in practical applications.