When evaluating PAC (Pump and Compressor) seals, you must prioritize material compatibility and pressure ratings. Ensure the seals utilize high-grade materials such as Silicon Carbide (SiC), Tungsten Carbide (TC), or Carbon-Graphite for the seal faces. The secondary seals (O-rings) should be made of Viton (FKM), EPDM, or PTFE depending on the chemical nature of the fluid. For high-performance applications, verify that the seals can withstand pressures up to 25 bar and temperatures ranging from -40°C to 220°C.