Short answer: to specify a replacement PTFE machined seal for a pump, send: the failed part or its drawing with dimensions at service temperature, pump model and duty (media, temperature, speed, pressure), material currently used with the failure mode observed, and quantity. If the original failed, the failure mode — not the drawing — should drive the material recommendation.
Reverse-engineering without a drawing
No drawing? Measure at room temperature and state the service temperature — PTFE’s expansion (~10x steel) means dimensions at 20°C are not service dimensions. Send the failed part itself: wear patterns and deformation are diagnostic data a manufacturer reads like a chart.
Failure modes that change the material
- Cold-flow flattening: virgin was under load — move to filled grade.
- Wear tracks: counterface or PV exceeded — carbon/graphite grades and counterface review.
- Chemical softening (rare): check for the true exceptions — usually it’s absorption and heat-up blistering instead.
Chunhuan reverse-engineers and machines pump seals from its own rod stock since 1985, ±0.05 mm under SPC, first-article inspection standard. Send the part plus the duty; the quote names grade and the fix for the failure you observed.
Frequently Asked Questions
Can you make a PTFE pump seal without a drawing?
Yes — send the failed part with dimensions noted at room temperature plus the service temperature, and the duty. Wear patterns guide the material choice.
Why did my PTFE pump seal flatten?
Cold flow under sustained load. The fix is a filled grade (glass/bronze) or redesigned load distribution — not a thicker virgin part.
What should a replacement seal RFQ include?
Part dimensions at known temperature, pump model and duty, current material with failure mode, and quantity with forecast.
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