How to Choose the Right Mechanical Seal Materials for Your Pump Application
Mechanical Seal Material Selection Guide
Choosing the right mechanical seal material is crucial for performance, longevity, and safety. This guide outlines common material combinations and when to use them, including a quick reference chart at the end.
Standard Materials (Default Option)
- Rubber Parts: typically Buna / Nitrile
- Metal Parts: 304 Stainless Steel
- Seal Faces: M106K grade Carbon (or better) with Ceramic (99%+ purity)
- Applications:
- Temperatures under 200°F
- Liquids with Neutral pH or close to it
- Fluids without abrasive media
This is the most commonly used option for general-purpose sealing with clean water, light chemicals, and non-aggressive environments.
Material Upgrade Alternatives for Rubber Parts
FKM (Viton from Dupont)
- Rubber Parts Upgrade (vs standard Buna-N)
- Temperature Range: Up to 450°F
- Chemical Resistance: Excellent, especially for solutions like bleach
- Notes:
- Greater chemical resistance than Buna
- Ideal for aggressive or high-temp chemical environments
- Be sure to verify chemical compatibility before choosing
EPDM
- Rubber Parts Alternative (vs standard Buna-N)
- Temperature Range: Up to 300°F
- Applications:
- Hot water and steam
- Caustic solutions
- Closed-loop systems with glycol or rust inhibitors
- Notes:
- More cost-effective than FKM
- Common in OEM circulator systems
Material Upgrades for Seal Faces
Carbon vs. Silicon Carbide (CAR/SIC)
- Face Combination (SIC)
- Performance:
- Maximum pressure handling
- Minimal friction, excellent for high temperatures
- Best For:
- Demanding applications needing maximum pressure rating
Carbon vs. Tungsten Carbide
- Face Combination
- Notes:
- Similar high pressure performance as silicon
- Slightly softer than silicon in abrasion resistance
- Superior impact resistance – great for rough handling or tight installs
Silicon Carbide vs. Silicon Carbide (SIC/SIC)
- Face Combination
- Performance:
- High wear and chemical resistance
- Low friction and strong in abrasive or contaminated media
- Best For:
- Wastewater
- Slurry and abrasive applications
Carbon vs. Ni-Resist / Stainless Steel
- Face Combination
- Application:
- Must be used with lubricating fluids like diesel fuel, oils, or glycols
- Not suitable for water-only service as its not a lubricating liquid
- Limitations:
- Performance is reduced to ~30% of the seal’s normal rating
- Metal seats are softer and wear faster in poor lubrication environments
Quick Reference Chart
| Combination | Best Use Case | Temp Rating | Notes |
|---|---|---|---|
| Buna/Carbon vs. Ceramic | Clean water, neutral pH, low temp | less than 200°F | Default setup |
| FKM (Viton)/Carbon vs. Ceramic | Bleach, aggressive chemicals | less than 450°F | Check chemical compatibility |
| EPDM/Carbon vs. Ceramic | Caustic fluids, glycol systems | less than 300°F | More economical than Viton |
| Carbon vs. Silicon Carbide | High temp/pressure | High | Low friction, durable |
| Carbon vs. Tungsten Carbide | High pressure + impact resistance | High | Great for shock-prone installs |
| Silicon Carbide vs. Silicon | Abrasive & chemical-rich environments | High | Strong wear resistance |
| Carbon vs. Ni-Resist/SS | Diesel, oil, glycol (lubricating) | Varies | Only 30% of standard rating in non-lube conditions |
Let us know if you’d like help selecting the right material for your application!
Shaft Seals
Shaft seals used to prevent fluid leakage along rotating shafts in pumps, mixers, and other mechanical systems