| Carbon vs. Silicon Carbide | Resin-impregnated carbon stationary face with silicon carbide rotating face | Water-based chemicals, dilute acids, dilute alkalis, solvents, and many general process fluids | Approximately -20°C to 180°C, depending on elastomer and equipment design | Commonly up to approximately 20 bar in standard arrangements | Commonly suitable for peripheral speeds up to approximately 20 m/s | General chemical pumps, water treatment, light-duty process service, and utility systems | ★★★★☆ | Good general-purpose performance. Carbon may be unsuitable for strongly oxidizing fluids or abrasive slurries. |
| Silicon Carbide vs. Silicon Carbide | Silicon carbide against silicon carbide, commonly with secondary elastomer seals | Strong acids, many alkalis, corrosive chemicals, high-purity fluids, and abrasive process liquids | Approximately -30°C to 200°C, subject to elastomer and thermal conditions | Commonly up to approximately 25 bar, depending on seal design and operating stability | Commonly suitable for peripheral speeds up to approximately 25 m/s | Corrosive chemical transfer, wastewater, crystallizing fluids, and fluids containing fine solids | ★★★★★ | Excellent hardness, wear resistance, and corrosion resistance. Brittle faces require clean installation and proper alignment. |
| Tungsten Carbide vs. Silicon Carbide | Tungsten carbide against silicon carbide | Abrasive chemicals, slurries, contaminated liquids, and fluids with suspended solids | Approximately -20°C to 180°C, depending on the binder, elastomer, and design | Commonly up to approximately 25 bar in engineered seal arrangements | Commonly suitable for peripheral speeds up to approximately 20 m/s | Abrasive chemical processing, mineral slurries, pigments, and solids-bearing liquids | ★★★★★ | Strong resistance to abrasion and impact. Chemical compatibility should be checked because some carbide binders can be attacked by specific chemicals. |
| Carbon vs. Ceramic | Resin-impregnated carbon against alumina ceramic or reaction-bonded ceramic | Clean water, mild chemicals, dilute detergents, and non-abrasive process liquids | Approximately -20°C to 150°C, depending on the elastomer and seal construction | Commonly up to approximately 12 bar in standard pump applications | Commonly suitable for peripheral speeds up to approximately 15 m/s | Low-cost chemical pumps, cooling-water systems, and general industrial circulation | ★★★☆☆ | Cost-effective for clean fluids. It is less suitable for abrasive, highly corrosive, or thermally demanding service. |
| Tungsten Carbide vs. Tungsten Carbide | Tungsten carbide against tungsten carbide | Abrasive liquids, particle-loaded chemicals, slurry, and high-wear process fluids | Approximately -20°C to 180°C, depending on the material grade and elastomer | Commonly up to approximately 30 bar in specially engineered designs | Commonly suitable for peripheral speeds up to approximately 25 m/s | High-wear chemical processing, slurry circulation, and heavy-duty pump service | ★★★★☆ | Very good wear and impact resistance. The exact carbide grade and binder chemistry are important in corrosive service. |
| Diamond-Coated Face Pair | Diamond-coated silicon carbide or tungsten carbide faces | Highly abrasive fluids, fine solids, difficult slurries, and selected corrosive chemical mixtures | Approximately -20°C to 180°C, subject to coating system and secondary seals | Commonly up to approximately 25 bar, depending on the seal arrangement | Commonly suitable for peripheral speeds up to approximately 25 m/s | Severe abrasion, high-value process fluids, and applications where extended seal life is important | ★★★★★ | Outstanding wear resistance but generally higher cost. It requires correct face loading, lubrication, cooling, and installation control. |
| Double Mechanical Seal | Material pairing selected according to the process fluid; commonly carbon, silicon carbide, or tungsten carbide | Highly toxic, volatile, flammable, crystallizing, or environmentally sensitive chemicals | Approximately -20°C to 200°C, depending on the barrier system and elastomer | Commonly up to approximately 30 bar on the process side in engineered systems | Commonly suitable for peripheral speeds up to approximately 20 m/s | Hazardous chemical service, emissions control, aggressive solvents, and fluids that must not contact the atmosphere | ★★★★★ | Provides improved containment and lubrication control. Requires a compatible barrier or buffer fluid system and additional monitoring. |
| Bellows Mechanical Seal | Metal bellows with carbon, silicon carbide, or tungsten carbide faces | Corrosive chemicals, high-temperature fluids, and services where dynamic O-ring movement should be avoided | Approximately -40°C to 350°C for selected metal-bellows designs; elastomer-bellows designs are lower | Commonly up to approximately 25 bar, depending on bellows geometry and operating conditions | Commonly suitable for peripheral speeds up to approximately 25 m/s | High-temperature chemical pumps, thermal fluids, and corrosive services with demanding elastomer conditions | ★★★★☆ | Reduces dynamic secondary-seal wear. Temperature, pressure, corrosion allowance, bellows fatigue, and face loading must be evaluated together. |