Selecting the correct mechanical seal hinges on matching its specifications to your application’s core parameters—including the fluid handled, operating conditions, and equipment design—to ensure long-term reliability and leakage prevention.
Follow this 5-step framework to make an accurate selection:
1. Define the Fluid (Medium) Characteristics
The fluid being sealed is the most critical factor, as it directly impacts material compatibility and seal design.
- Chemical Compatibility: Confirm the seal’s materials (seal faces, elastomers, metal components) resist corrosion, swelling, or degradation by the fluid. For example:
- Use PTFE elastomers for strong acids/alkalis.
- Choose silicon carbide (SiC) seal faces for abrasive fluids (e.g., slurries) to avoid rapid wear.
- Physical State: Differentiate between liquids, gases, or volatile fluids. Gases often require seals with tighter clearances or secondary sealing elements to prevent leakage.
- Viscosity & Solids Content: High-viscosity fluids may need larger spring forces for face contact; fluids with solids (e.g., slurries) require robust, clog-resistant designs (e.g., unbalanced seals with wide gaps).
2. Match to Operating Conditions
Seal performance is heavily influenced by temperature, pressure, and speed—ensure these align with the seal’s rated limits.
- Temperature: Select seals rated for your fluid’s operating and startup/shutdown temperatures. For high-temperature applications (>200°C), use graphite-filled PTFE or metal bellows instead of standard elastomers.
- Pressure: Choose between balanced (for high pressure, >10 bar) or unbalanced seals (for low pressure, <10 bar). Balanced seals reduce face loading, minimizing wear under high pressure.
- Shaft Speed: Verify the seal’s maximum allowable speed (RPM) matches your equipment. High-speed applications may require seals with reduced mass (e.g., compact cartridge designs) to avoid centrifugal force damage.
3. Consider Equipment Design & Installation Space
The seal must fit your equipment’s physical constraints and mounting style.
- Shaft Size & Type: Match the seal’s inner diameter to the shaft’s outer diameter. For stepped or tapered shafts, select seals with compatible adapters or custom designs.
- Seal Chamber Dimensions: Ensure the seal fits within the available space (length, diameter) of the equipment’s seal chamber. Cartridge seals are pre-assembled and easier to install in tight spaces than component seals.
- Mounting Orientation: Seals installed vertically (e.g., on vertical pumps) may need modified spring designs to maintain consistent face contact, unlike horizontal mounts.
4. Evaluate Seal Type for Your Application
Choose a seal configuration based on your equipment type and reliability needs.
- Cartridge Seals: Pre-assembled, easy to install (reduces human error), ideal for pumps or rotating equipment where installation precision is critical.
- Component Seals: Require on-site assembly, more flexible for custom equipment but demand skilled installation.
- Double Mechanical Seals: Used for toxic, flammable, or environmentally hazardous fluids—they provide a secondary barrier (with a buffer fluid) to prevent leakage.
- Single Mechanical Seals: Cost-effective for non-hazardous fluids (e.g., water) where minimal leakage is acceptable.
5. Factor in Maintenance & Cost Goals
Balance upfront cost with long-term maintenance needs.
- Maintenance Requirements: If your application allows for frequent maintenance, a standard component seal may suffice. For remote or hard-to-access equipment, choose durable, low-maintenance options (e.g., SiC-faced cartridge seals).
- Total Cost of Ownership (TCO): Avoid selecting the cheapest seal if it has a short lifespan (leading to frequent replacements). A higher-quality seal (e.g., with corrosion-resistant materials) often reduces TCO by minimizing downtime and repair costs.
Jiaxing Burgmann Mechanical Seal Co., Ltd
Email: doris@mechanicalseal.com.cn
Skype: kathysunlin
Fax: 86-573-84072317
Mob: 86-15381220188
WhatsApp: 8615958372402
Website: www.industrial-mechanicalseals.com
Add: A-5 Wanyangzhongchuangcheng, Ganyao Town, Jiashan county, Jiaxing, Zhejiang, China. 314107
