Pressure-Sensitive Gasket is a functional material that activates its sealing performance through pressure, widely used in sealing, buffering, and conducting scenarios. Here is a detailed guide on the use of pressure-sensitive gaskets, including selection, installation, maintenance, and common problem solutions:
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### **1. Types and Selection of Pressure-Sensitive Pad
1. **By Material Classification**
- **Rubber Types** (e.g., Nitrile Rubber, Fluorocarbon Rubber): Oil-resistant and chemically resistant, suitable for automotive and chemical equipment.
- Silicone products: High-temperature resistant (-50°C to 250°C), food-grade safety, suitable for medical and food machinery.
- **Polyurethane**: High elasticity, wear-resistant, often used in buffering and shock absorption scenarios.
- **Conductive/Insulating Materials**: Containing conductive particles (e.g., carbon fiber) or insulating layers, used for electromagnetic shielding or circuit isolation in electronic devices.
2. **By Structure Classification**
- **Single-layer gasket**: Simple sealing applications, low cost.
- **Composite Gaskets** (e.g., metal+rubber): Resistant to high pressure, anti-creep, suitable for high-load scenarios such as flanges and valves.
- **Adhesive Backed Gasket**: Comes with pressure-sensitive adhesive, no need for additional fixing, suitable for quick installation.
3. **Selection Key Parameters**
- **Workload**: Static pressure (such as sealing) or dynamic pressure (such as vibration environments).
- **Temperature Range**: The material's temperature resistance must cover the extreme temperatures of the application scenario.
- **Media Compatibility**: Whether it comes into contact with corrosive substances such as oil, acid, alkali, solvents, etc.
- **Thickness and Compression Rate**: The compression rate is usually controlled at 15% to 30% to maintain the seal.
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### **Steps for Installation and Operating Standards**
1. Surface Pretreatment
- **Clean the surface**: Use solvents such as isopropyl alcohol or acetone to remove oil, rust, or residual adhesive.
- **Flatness Inspection**: Use a straightedge or feeler gauge to check if the installation surface is flat. If it is not flat, it needs to be sanded or filled.
- **Drying Treatment**: Ensure the surface is dry to avoid moisture affecting the adhesive's adhesive properties.
"2. **Gasket Positioning and Installation"**
- **Adhesive-free gasket"：
1. Align the gasket with the installation position to avoid misalignment.
2. Apply even pressure using bolts or clamps, and tighten the bolts in a "cross-cross" sequence to prevent excessive pressure in local areas.
- **Adhesive Backed Gasket**：
1. Peel off the release film, and press lightly to fix the adhesion position.
2. Use a roller or scraping tool to apply pressure from the center towards the edge to remove air bubbles.
3. **Pressure Control**
- **Initial Pressure**: Apply 50% to 70% of the design pressure to cause the gasket to initially deform and adhere to the surface.
- **Final Pressure**: Gradually increase the pressure to the design value to ensure that the gasket fully fills the microscopic gaps.
- **Dynamic Scenario** (e.g., Vibration Equipment): Periodic checks are required to ensure that the pressure is not decreasing.
4. **Sealing Test**
- **Air/Water Pressure Test**: Apply pressure to 1.5 times the working pressure, maintain for 5 minutes, and observe for any leaks.
- **Electronics**: Test the resistance value or signal stability of the conductive pad.
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### **3. Usage Notes
1. Avoid overpressure or underpressure.
- Insufficient pressure can lead to leaks, while excessive pressure can crush gaskets (especially soft materials such as silicone).
- Adjust the installation pressure based on the 'pressure-compression rate' curve provided by the gasket manufacturer.
2. **Temperature and Chemical Environment**
- **High-temperature Scenario**: Silicone gaskets should avoid being exposed to temperatures above 250°C for a long time, while fluorocarbon rubber can withstand temperatures up to 300°C.
- **Chemical Corrosion**: In a strong acid environment, preferentially choose PTFE gaskets.
3. **Long-term Maintenance**
- **Regular Inspection**: Check the gasket every 3~6 months to ensure it has not deteriorated, cracked, or permanently deformed.
- **Replacement Cycle**: Rubber gaskets typically have a life span of 2~5 years, while silicone gaskets can last 5~8 years (depending on the working conditions).
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### **Section Four: Common Questions and Solutions**
| **问题现象** | **可能原因** | **解决方法** |
|----------------------|-------------------------------|-------------------------------------------|
| Continuous leakage | Installation surface is uneven, gasket thickness is insufficient | Sanding the installation surface or replacing the thickened gasket |
| Cracks at the gasket edge | Inhomogeneous pressure or material aging | Re-apply even pressure or replace with aging-resistant materials (e.g., EPDM) |
Decrease in conductivity | Surface oxidation or contamination | Clean the surface or replace the conductive gasket with an antioxidant coating
| Backing tape peeling off | Surface not thoroughly cleaned or temperature too high | Re-clean and select a heat-resistant adhesive (e.g., silicone backing tape) |
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### **Special Scene Application Techniques**
1. High-temperature and high-pressure sealing
- Select metal-wrapped gaskets (e.g., stainless steel + graphite), coupled with pressure-sensitive adhesive for enhanced adhesion.
- Tighten the bolts after pre-tightening during installation (considering the difference in thermal expansion coefficients).
2. **Vacuum Environment Sealing**
- Choose low-volatile silicone or fluorocarbon rubber gaskets to avoid material emissions polluting the vacuum chamber.
3. **Frequent Disassembly Scenario**
- Use reusable adhesive backing (such as acrylic adhesive) or magnetic pads for easy maintenance.
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Section 6: Selection and Procurement Recommendations
1. **Clear working conditions requirements**
- Provide detailed information about pressure, temperature, and medium type to the supplier to avoid selection errors.
2. **Small-volume Testing**
- It is recommended to conduct a small sample test under the new working condition to verify the sealability and durability.
