A dosing pump cannot have grease anywhere near the head, which leaves PEEK as one of the few materials that can run dry and still hold a tolerance. Pumps & Compressors duty is continuous running, thrust reversal and process fluid along the shaft; the material is what decides whether the bearing survives it.
| Industry duty | continuous radial load plus axial thrust that reverses on start-up |
|---|---|
| Typical media | water, process fluid, washdown, solvent |
| Housing temperature | −20 to +150 °C |
| Material and grade | PEEK polymer |
| Hardness | — (polymer, 90 Shore D) |
| Temperature ceiling | 250 °C |
| Corrosion / chemical | most chemicals and solvents |
| Relative cost | ≈5× a polymer, 1/3 of ceramic of a standard 52100 bearing |
In a metering pump the eccentric or the connecting rod runs in the same compartment as the process fluid, and any lubricant that migrates becomes contamination. PEEK solves that: it has a low friction coefficient against steel, keeps its dimensions at 150 °C, and resists the solvents that would swell nylon. The trade is load — it is a polymer, and the PV limit arrives quickly.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| Dosing pump eccentric | PEEK bush | PEEK bush, carbon-fibre filled | Dry running against a stainless eccentric; the CF fill raises PV and cuts wear. |
| Compressor connecting rod | PEEK bush | PEEK bush, 1 mm wall | No oil in the compression chamber; the bush is the only lubricant. |
| Chemical metering valve stem | PEEK thrust washer | PEEK thrust washer | Solvent resistant and dimensionally stable at 150 °C. |
| Material | Fit here | Choose it when |
|---|---|---|
| PEEK | Best fit | Dry running in contact with process fluid, up to 250 °C. |
| PTFE | Workable alternative | Stronger chemical resistance but cold-flows under load; filled PTFE for low load only. |
| Bronze | Workable alternative | Where a grease or oil film is available — cheaper and carries far more load. |
Yes, at low PV. It transfers a thin film onto the steel counterface, and that film is the lubricant. The first few hundred cycles are the wearing-in period.
PTFE for the widest chemical range and the lowest friction; PEEK for load, temperature and wear. Filled PTFE sits between them.
Heat from speed, not chemical attack. A dry PEEK bush run above its PV limit softens, smears and seizes.
Hardness, temperature, corrosion and equivalents for PEEK.
Read →Typical duty, recommended types and suffixes for pumps.
Read →Standard process pumps — impeller and seal-side positions in ISO and ANSI process pumps.
Read →Washdown & food pumps — food, beverage and CIP-washdown pumps where water reaches the bearing housing.
Read →Send the position, bore size, quantity and the medium it sees. We reply with the material certificate, clearance class, lubricant and price within 30 minutes on working days.