Fuel Cell Gaskets

Stockwell Elastomerics has been a supplier of high quality silicone rubber to the fuel cell market for many years. SSP4749-XX platinum cured high consistency rubber (HCR) from Stockwell Elastomerics offers excellent temperature resistance, strength and inertness for PEM fuel cell stacks. The platinum cured silicone rubber, also called addition cured silicone rubber, does not have the same organic acids that naturally occur in peroxide cured silicone rubber.

SSP4749-XX can be molded into flat, window gasket configurations or made with added sealing beads. Fuel cell gaskets can be die cut, waterjet cut or molded to custom geometries as specified by OEM engineers. These gaskets can be made with thin cross-sections, typically specified from a range of durometer (30 – 70 duro Shore “A”).

Improved Compression Set Properties After Post-Cure

When post-cured for 2 hours at 200°C (392°F), SSP4749-XX has improved compression set properties. For example, this post-cure improves the compression set values of SSP4749-50 from 19% to 11% at 70°C and from 33% to 12% at 100°C. The improved compression set, along with the purity of the platinum cure silicone have found favor with the fuel cell industry. The LV suffix, such as SSP4749-XXLV, is used to indicate post-cure.

High Consistency Rubber (HCR) – SSP4749-XX and SSP4749LV Availability

Stockwell Elastomerics offers SSP4749-XX silicone rubber sheets in 12″ wide roll stock from .015 ± .002” thick to .062 ± .005” thick. Standard colors are unpigmented (translucent) and black, however white and custom colors are available with a minimum production run. Water jet cutting or die cutting can be use to manufacture gaskets to specification.

Typical Durometer Range of SSP4749-XX Platinum Cure Silicone Specified for Fuel Cell Gaskets

• SSP4749-30 – 30 durometer Platinum Cured High Consistency Rubber (HCR)
• SSP4749-30LV – 30 durometer Platinum Cured High Consistency Rubber (HCR) with Post-Cure
• SSP4749-40 – 40 durometer Platinum Cured High Consistency Rubber (HCR)
• SSP4749-50 – 50 durometer Platinum Cured High Consistency Rubber (HCR)
• SSP4749-50LV – 50 durometer Platinum Cured High Consistency Rubber (HCR) with Post-Cure
• SSP4749-60 – 60 durometer Platinum Cured High Consistency Rubber (HCR)
• SSP4749-60LV – 60 durometer Platinum Cured High Consistency Rubber (HCR) with Post-Cure
• SSP4749-70 – 70 durometer Platinum Cured High Consistency Rubber (HCR)
• SSP4749-70LV – 70 durometer Platinum Cured High Consistency Rubber (HCR) with Post-Cure

Fuel Cell Cushioning

Much like batteries for Electric Vehicles (EVs), a fuel cell stack needs expansion cushions and padding that can compress and expand with the stack. Silicone foam is an excellent choice because of its exceptional ability to rebound after many cycles. Also, silicone foam is mechanical stabile at high and low temperatures. Many other foam materials will become very firm at low temperature and soft at high temperatures. Silicone foam materials offered by Stockwell Elastomerics are UL 94V-0 flame rated, meaning it will self-extinguish within 10 seconds, with no drips allowed, on a vertical burn. Lastly, Stockwell Elastomerics’ silicone foams are also rated for smoke and toxicity commonly used for airplanes and rail applications.

• Ultra Soft BISCO® Silicone Foam: BF-2000 (1.5 psi)
• Extra Soft BISCO® Silicone Foam: BF-1000 (1 – 5 psi) and F12 (4 psi)
• Soft BISCO® Silicone Foam: HT-870 (2 – 7 psi)
• Medium BISCO® Silicone Foam: HT-800 (6 – 14 psi)
• Firm BISCO® Silicone Foam: HT-820 (12 – 20 psi)
• Extra Firm BISCO® Silicone Foam: HT-840 (16 – 26 psi)
• BISCO® Silicone Foam Gasket Tape: HT-800 gasket tape, rolls with acrylic adhesive