| 1 | Single Pusher Seal | An elastomer or polymer secondary seal moves axially with the rotating face. | Approximately −20°C to 180°C, depending on the elastomer and face materials. | Commonly up to about 10 bar; higher values require suitable design and speed limits. | General pumps, water circulation, HVAC systems, and low-to-moderate duty process equipment. | Carbon versus silicon carbide or tungsten carbide; elastomer options include EPDM, NBR, FKM, or PTFE-based compounds. | Simple construction, broad availability, and straightforward installation. | The sliding secondary seal can be affected by shaft damage, deposits, or excessive axial movement. |
| 2 | O-Ring Pusher Seal | A dynamic O-ring provides secondary sealing while the spring-loaded face compensates for wear. | Approximately −40°C to 200°C, depending on O-ring compound and process fluid. | Typically up to about 10–15 bar in standard pump service. | Clean water, oils, mild chemicals, rotating equipment, and applications requiring easy size availability. | Carbon, ceramic, silicon carbide, or tungsten carbide faces; NBR, EPDM, FKM, or PTFE O-rings. | Cost-effective, easy to source, and adaptable to many standard shaft sizes. | O-ring friction and chemical compatibility must be checked carefully; unsuitable elastomers may swell or harden. |
| 3 | Multi-Spring Pusher Seal | Several springs distribute closing force around the seal circumference. | Approximately −40°C to 220°C, subject to material selection and spring exposure. | Usually up to about 16 bar for suitable pump designs. | Process pumps, industrial water systems, oils, solvents, and moderate-duty chemical services. | Carbon, silicon carbide, or tungsten carbide faces; elastomers selected according to temperature and chemical exposure. | More balanced face loading than many single-spring designs and good tolerance of moderate operating variation. | Exposed springs may collect solids or crystallized process fluid, increasing the risk of uneven loading. |
| 4 | Stationary-Spring Pusher Seal | The spring assembly remains stationary while the mating seal face rotates. | Approximately −40°C to 220°C, depending on the secondary seal and face materials. | Commonly up to about 20 bar in properly selected equipment. | Higher-speed pumps, equipment with solids in the fluid, and services where spring balance is important. | Silicon carbide or tungsten carbide faces are common for abrasive service; elastomers or PTFE-based secondary seals are selected by compatibility. | Reduced rotational spring stress and lower sensitivity to centrifugal effects at elevated speed. | Typically requires more installation space and may be less suitable where axial movement is substantial. |
| 5 | Cartridge Pusher Seal | The seal, sleeve, gland, and setting elements are supplied as a pre-assembled unit. | Approximately −40°C to 220°C, depending on the complete material package. | Often rated around 15–25 bar, subject to diameter, speed, pressure, and balance ratio. | Industrial pumps, energy equipment, chemical processing, and maintenance-sensitive installations. | Carbon, silicon carbide, tungsten carbide, stainless steel, and elastomers selected for the process fluid. | Fast installation, reduced setting errors, and good repeatability during maintenance. | Higher purchase cost and larger axial envelope than many component-style seals. |
| 6 | Balanced Pusher Seal | A hydraulic balancing arrangement lowers the closing force acting on the seal faces. | Approximately −40°C to 250°C, depending on face, spring, and secondary-seal materials. | Often suitable for approximately 20–40 bar when correctly engineered. | High-pressure pumps, hot fluids, hydrocarbons, boiler-feed systems, and demanding process services. | Silicon carbide, tungsten carbide, or carbon faces; graphite, FKM, PTFE, or other compatible secondary seals. | Lower face loading helps control heat generation, wear, and leakage at higher pressure. | More sensitive to dimensional accuracy, pressure changes, and correct installation than unbalanced designs. |
| 7 | Heavy-Duty Slurry Pusher Seal | A reinforced pusher arrangement uses wear-resistant faces and robust components for abrasive fluids. | Approximately −20°C to 180°C, depending on slurry composition and material selection. | Typically about 6–16 bar in abrasive slurry service; actual limits depend strongly on speed and solids content. | Mining pumps, mineral processing, wastewater with solids, pulp handling, and abrasive suspension service. | Silicon carbide or tungsten carbide faces, hard metal components, and abrasion-resistant elastomers or PTFE-based materials. | Improved resistance to abrasion, solids contamination, and demanding operating conditions. | Higher cost, greater installation requirements, and potential face damage if dry running occurs. |