Selecting the Right Piston Seal Material for Eldex Pumps
In precision fluid metering — whether for HPLC, chemical processing, or advanced laboratory research — the smallest components often make the most significant difference. One such component is the piston seal material inside your Eldex Optos Series pump. The seal doesn’t just prevent leaks; it directly affects performance, durability, chemical compatibility, and even compliance with environmental standards.
This guide breaks down the two optional piston seal materials available for Optos pumps — UHMW PE and Graphite Fiber Reinforced PTFE — so you can match your application needs with the right solution.
GFR PTFE: Fluoropolymers for Extreme Environments
Graphite Fiber Reinforced Polytetrafluoroethylene is the gold standard for chemical inertness, reinforced with graphite fibers to enhance wear resistance. For these reasons, GFR PTFE is the standard seal material for Optos Series stainless steel (SS316) and Hastelloy pumps with spring-energized seals, suitable for demanding environments.
Key Features
- Near-universal chemical compatibility
- Excellent wear resistance across a wide speed and pressure range
Chemical Compatibility
- Inert against most fluids
- Compatible with supercritical CO₂, sodium hydroxide (≤80%), and sulfuric acid (all concentrations)
- Less suitable for nitric, hydrofluoric, or concentrated sulfuric acids in some conditions
Temperature Range
- Low: Remains flexible to -200 °C (-328 °F) and even -260 °C (-436 °F)
- High: Continuous use up to 260 °C (500 °F); short-term peaks at 315 °C (599 °F)
Part #s for GFR PTFE piston seals standard on Eldex Optos stainless steel and Hastelloy pump models:
Piston Size | 3/32” Piston | 1/8” Piston | 1/4” Piston |
316 Stainless Pump | 5911 | 5941 | 5944 |
Hastelloy-C Pump | n/a | 6048 | 6080 |
UHMW PE: Durable, PFAS-Free for Moderate Conditions
Ultra-High-Molecular-Weight Polyethylene is a non-fluorinated thermoplastic known for its toughness, abrasion resistance, and low-friction properties. As a PFAS-free option, it supports environmentally conscious operations without compromising reliability. For chemical compatibility, UHMW PE is the standard seal material on Optos Series PEEK pumps.
Key Features
- Excellent wear life under severe operating conditions
- Broad chemical compatibility, particularly with water and water-based fluids
Chemical Compatibility
- Resistant to most acids, alkalis, and solvents
- Avoid strong oxidizers and supercritical CO₂, which can cause swelling
Temperature Range
- Low: Functional to -200 °C (-328 °F), though becomes brittle below -150 °C (-238 °F)
- High: Best below 80 °C (176 °F); some grades tolerate up to 160 °C (320 °F)
Part #’s for UHMW PE piston seals standard on Eldex Optos PEEK pump models:
Piston Size | 3/32” Piston | 1/8” Piston | 1/4” Piston |
PEEK Pump | 5914 | 6007 | 6010 |
Conclusion
By matching your application requirements with the right seal material—and validating compatibility through testing—you can extend the life of your Eldex pump while ensuring peak performance.
Material | PFAS-Free? | Key Strengths | Chemical Resistance Highlights | Temperature Range | Best Applications |
GFR PTFE | No | Inert, versatile | Near-universal; resists strong acids/scCO₂ | -260°C to 260°C | Piston seals in harsh/chemical environments |
UHMWPE | Yes | Abrasion-resistant, low-friction | Good for acids/alkalis; avoid oxidizers/scCO₂ | -150°C to 80°C | Piston seals in moderate conditions |
