How to read a mechanical seal drawing
Faces, springs, drive, elastomers — what actually matters when you are staring at a seal drawing, and what to send us when there is no drawing at all.
1. Seal faces first
The faces do the sealing. Look for the face-material pairing — typical combinations in our catalog include carbon graphite running against silicon carbide, ceramic, or tungsten carbide. The pairing decides what the seal tolerates: abrasive or solids-containing media need hard faces such as silicon carbide, while clean, well-lubricated duties run fine on carbon. If the drawing names only one face, the mating ring material is the first thing we confirm in technical review.
2. Springs and drive arrangement
Single-spring, multi-spring, or bellows construction tells you how the faces stay loaded — and whether the design suits the duty. Multi-spring rotating units spread the load evenly and suit general pump service; single-spring units are simpler and common in agitator and light duties; bellows designs remove the dynamic O-ring for high-temperature or corrosive service. Balanced versus unbalanced construction decides the pressure the seal can take: our balanced component seals cover up to 35 bar, unbalanced ones up to about 10 bar, and every figure is confirmed against your application data before quoting.
3. Elastomers and metallurgy
The secondary seals and metal parts decide chemical compatibility. Common elastomers across our range are FKM, FFKM, EPDM, NBR, and PTFE; metal components are typically SS316 or SS304, with Hastelloy, Monel, or Alloy-20 on demanding duties. A drawing that specifies faces but not elastomers is incomplete for chemical service — media and temperature pick the elastomer, not the other way round. See ourelastomer compatibility reference for the failure modes we see most often.
4. Operating limits and envelope
Shaft size, seal-chamber dimensions, pressure, temperature, and speed define the envelope — many of our series follow the DIN 24960 envelope. Treat brochure maxima as separate columns, never as a combined promise: 150 bar at 25 °C is a different seal than 150 bar at 300 °C. Limits are always checked at the intersection of pressure, temperature, media, and speed during technical review.
No drawing? Send this instead
A photo of the installed seal, the equipment model, shaft diameter, and operating conditions are often more useful than a part number. Our RFQ checklist lists exactly what engineering needs — or skip straight to the form.