Knowledge of the selection system of solenoid valves in pneumatic systems is essential for learning non-standard design!
The solenoid valve in the pneumatic system is the core component for controlling the direction, pressure, and flow rate of gas flow. Its selection directly affects the performance and reliability of the system. For non-standard designs, the selection of solenoid valves needs to comprehensively consider multiple dimensions such as working conditions, performance parameters, and compatibility. The following is a systematic summary of selection knowledge:
I. Core Parameters and Selection Basis of Solenoid Valves
1. Medium characteristics
Does the compressed air contain oil, moisture, or particulate matter? The valve body material (such as aluminum alloy, stainless steel, engineering plastic) and sealing material (NBR, FKM, PTFE) need to be matched.
If the medium is corrosive gas, a fully stainless steel valve body with fluororubber sealing should be selected.
2. Working pressure range
Minimum starting pressure: Direct-acting valves typically require ≥0.15MPa, while pilot-operated valves can be as low as 0.01MPa.
Upper pressure resistance limit: The conventional valve body can withstand a pressure of 1.0MPa. For high-pressure scenarios, a specification of 1.6MPa or above should be selected.
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3. Flow demand (Cv value /Kv value)
Calculate the required flow rate based on the cylinder speed and select a valve with a matching Cv value.
Q: Flow rate L/min, D: cylinder diameter cm, L: Stroke cm, P: Pressure MPa, t: time s
The valve port diameter should be greater than or equal to the cylinder interface size to avoid the throttling effect.
4. Voltage and Power Consumption
DC (DC24V) is suitable for low-power consumption and explosion-proof scenarios. AC220V is low in cost but prone to overheating.
Low-power coils (≤1.5W) can reduce heat generation and extend lifespan.
5. Mode of movement
Single electronic control (spring return): Automatically resets upon power failure, suitable for safety-first scenarios.
Dual electronic control (magnetic latching): It requires dual signal control and is suitable for occasions where position retention is needed.
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Ii. Selection of Structural Types
The direct-acting principle directly drives the valve core by electromagnetic force. Advantages: Zero-voltage start-up and fast response (≤20ms); Disadvantages: Small diameter (generally ≤Φ6mm); Applicable scenarios: small traffic and high-frequency actions.
The pilot-operated principle uses air pressure to assist in driving the valve core. Advantages: Large flow rate and low power consumption; The disadvantage is that the minimum pilot pressure (≥0.15MPa) is required. Applicable scenarios: Large cylinders and main control valves.
Iii. Environmental Adaptability Design
1. Temperature range
Standard valve: 5℃ to 50℃ High-temperature valves (such as the SMCSY7000 series) can reach 80℃. The low-temperature valve requires special sealing.
2. Protection grade
IP65 (dust and water resistant) for use in damp environments; The explosion-proof valve (ExdIICT6) is used in flammable and explosive places.
3. Vibration and Shock
For high-frequency vibration scenarios, choose valves with mechanical locking (such as FestoMS6LS) to prevent misoperation.
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Iv. Special Considerations for Non-standard Design
1. Compact installation
Multi-way valve groups (such as FestoCPV10) save space and support ISO5599/1 standard base plates.
2. Signal interface
For high-speed response scenarios, choose intelligent valves with bus interfaces (PROFINET/EtherCAT) to reduce wiring.
3. Energy-saving design
Pulse solenoid valves (intermittent power supply) can reduce energy consumption by 90% and are suitable for battery-powered equipment.
V. Example of Selection Process
1.Requirements Analysis: Cylinder diameter Φ50mm, stroke 200mm, action time 0.5s, working pressure 0.6MPa.
2. Flow calculation
Q 5 ^ 2 = 0.47 * * 20 * (0.6 + 1.02) / 0.5 material of 340 l/min
3. Select valve specifications: Choose pilot-operated 5-way valves with a Cv value of ≥1.2 (corresponding to a diameter of Φ12mm), such as the SMCVQZ series.
Vi. Common Misunderstandings and Solutions
Question 1: The valve body is leaking air
Countermeasures: Check the wear of the sealing ring and give priority to choosing valve cores with hard anodizing treatment (such as Burkert6014).
Question 2: The solenoid valve is overheating severely
Countermeasures: Switch to low-power coils or add heat sinks to avoid continuous power-on time exceeding 90%.
Above is Knowledge of the selection system of solenoid valves in pneumatic systems is essential knowledge for learning non-standard design! content. To learn more related information, visit https://www.joosungauto.com/.
