A mechanical seal keeps fluid from leaking along a pump shaft. They're a frequent wear item, and the right replacement comes down to the shaft size, the seal design and the materials that contact your fluid.
Size and design
- Shaft (or sleeve) diameter the seal fits — the primary dimension.
- Component seal (separate stationary + rotary parts) vs cartridge seal (pre-assembled unit — easier and more reliable to fit).
- Single seal vs double (for hazardous or abrasive media).
- Balanced vs unbalanced (balanced handles higher pressure).
Materials must suit the fluid
- Seal faces: carbon, ceramic, silicon carbide (SiC) or tungsten carbide — harder faces for abrasives.
- Elastomer (O-rings/bellows): NBR, EPDM, or Viton/FKM — chosen for chemical and temperature compatibility.
- Metal parts: stainless grade.
Lip / oil seals are different
If it's a simple rubber lip (oil) seal rather than a mechanical seal, identify it by three numbers — inner diameter × outer diameter × width (mm) — plus single or double lip and the material.
Send us the pump details
Give us the pump make/model and shaft size (or the seal part number), and we'll match the correct seal — face and elastomer materials included — and quote it.