Glad Hand Seal Guide
Everything you need to know about selecting, installing, and maintaining glad hand seals for commercial trucks and trailers.
Color Coding Explained
Glad hand seals are color-coded to match air brake line standards:
- 🔴 RED seals: Emergency/supply line (connects to trailer spring brakes)
- 🔵 BLUE seals: Service line (connects to trailer service brakes)
- ⚫ BLACK seals: Universal/service applications
Pro tip: Always match seal color to your glad hand color to maintain proper identification and avoid cross-connections.
Materials: Rubber vs. Polyurethane
Rubber Seals (Standard)
- Traditional material, proven reliability
- Good for moderate use (10,000-25,000 connect/disconnect cycles)
- More affordable upfront cost
- Best for: Fleets with regular replacement schedules
Polyurethane Seals (Premium)
- 50,000+ connect/disconnect cycle lifespan
- Better resistance to UV, ozone, and temperature extremes
- Maintains flexibility longer in cold weather
- Best for: High-use applications, extreme climates, lower total cost of ownership
When to Replace Seals
Replace glad hand seals when you notice:
- Air leaks at the glad hand connection
- Visible cracks, tears, or hardening
- Seal won’t stay seated in the glad hand
- Flattened or compressed appearance
- During routine PM inspections (recommended every 90 days for high-use fleets)
Installation Tips
- Remove old seal completely — don’t stack new over old
- Clean the seal groove of debris and old rubber
- Seat new seal firmly into groove with lip facing outward
- Test connection before putting truck in service
Questions? Call us at 800-884-6456 — we’re happy to help you choose the right seals for your application.