[ sealing ]
Choosing the right gasket material
Material selection When considering the gasket material, polytetrafluoroethylene( PTFE) is widely recognized for its outstanding chemical resistance, thermal stability, insulating properties, and low-friction characteristics. Its near-total inertness to most chemicals makes it particularly well-suited for the demanding conditions within electrolyzers. However, not all PTFE gaskets are the same. Their performance can vary considerably depending on the manufacturing process and the quality of the raw materials. PTFE gaskets generally fall into three main categories: 1. Skived PTFE: Offers excellent chemical resistance. It is prone to creep and cold flow under load, leading to sealing failures over time.
2. Structured PTFE: Enhanced with fillers like glass microspheres, silica, or barium sulfate, reducing creep and improving mechanical stability while still maintaining a good chemical resistance.
3. Expanded PTFE( ePTFE): Manufactured with a microporous structure, it provides superior compressibility and resilience while maintaining excellent chemical resistance.
Compared to skived PTFE, both structured and expanded PTFE gaskets offer improved
mechanical strength and reduced creep, making them more suitable for demanding environments within PEM and alkaline electrolyzers. Their enhanced properties ensure that the gaskets can withstand operational stresses over the long term, maintaining seal integrity and contributing to the overall efficiency and reliability of the hydrogen production process.
Furthermore, PTFE fluoropolymers provide excellent electrical stability across various environmental conditions, setting them apart from other insulating materials. For reference, pure PTFE exhibits superior electrical properties, with a high dielectric strength of around 24 kV / mm.
Sealing requirements Each type of electrolyzer has specific sealing needs. For example, PEM electrolyzers require thin gaskets that provide high electrical insulation. Structured PTFE gaskets( e. g., Tealon™ TF 1570) provide excellent mechanical stability and maintain a reliable seal under limited bolt preload.
In alkaline electrolyzers, the gasket must withstand exposure to caustic electrolytes like KOH. Expanded PTFE gaskets( e. g., TEADIT 24 SH) or structured PTFE( e. g., Tealon™ TF 1580) resist harsh chemicals while maintaining long-term sealing performance.
TEADIT 24 SH( left) and Tealon™ TF 1580( right)
46 Hydrogen Tech World | Issue 22 | June 2025