Pure expanded mineral graphite flake or chip particles are subjected to laminar swelling and are subsequently calendered into flexible foil without the use of any separate binder, a feature which guarantees a high degree of purity not associated with other graphite derivatives. The foil is processed in a number of ways to adapt the unique properties of the material to a variety of sealing needs The raw material is a mineral that is mined in a similar way to coal.
The sealability of graphite is akin to that associated with elastomeric materials but its temperature capability far exceeds that of even the most exotic rubber compound. Add to this an outstanding resistance to a wide range of organic and inorganic chemicals and it is easy to see why many regard graphite as one of the most important additions to the gasket manufacturer’s stock holding since the advent of polytetrafluoroethylene (PTFE).
TECHNICAL DATA | |
Purity / Sulphur Content max. ASTM C-816 | 98% / 700 ppm |
Bulk Density ASTM C-559 | 1.0 to 1.1 g/cc |
Ash Content ASTM C-561 | Less than 0.5% |
Leachable Chloride / Fluorides | 50 ppm max. ASTM D-512 |
Temperature Range | -200°C to +3000°C (Non-Oxidising) -200°C to + 500°C (Oxidising) -200°C to + 650°C (Steam) |
Tensile Strength / Stress Relaxation | 998 psi / DIN 52913 - 48 N/mm² |
Shore Hardness (D) / Creep Relaxation | 30 / At 100°C ASTM F-38 < 5% |
Sealability, ml/h Fuel A ASTM F-37B | <0.2 to 0.5 |
Electrical Resistance | 900 x 10-6 ohm cm parallel on surface 250,000 x 10-6 ohm perpendicular to surface |
Thermal Conductivity | 120 Kcal/m. Hr.°C parallel to surface 4 Kcal/m Hr.°C perpendicular to surface |
Coefficient of Thermal Expansion | 5 x 10-6 / °C parallel to surface 2 x 10-6 / °C perpendicular to surface |
Compressive Strength | more than 800 kg/cm² |
Ignition Loss / Operating Pressure | less than 1% / 140 bar (2058 psi) |
Resilient Rate / Density | more than 30% / 0.7 to 1.1 gr cm³ |
Compressibility ASTM F36A-66 | 40 to 45% |
Pure graphite is available in sheets or rolls and in a wide range of thicknesses