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P-Series Spec Table
P-Series Specifications — 42 sizes
JIS B 2401JIS B 2401-1
JIS P-series O-rings, primarily used as dynamic (piston/cylinder) seals per Japanese industrial standard.
Practical Notes
- Stretching an O-ring over 5% of its ID reduces cross-section and sealing performance. Select a size within proper stretch limits.
Selection Guide
JIS standard O-rings for reciprocating seals in pistons and cylinders. Select by cord diameter (W) and inner diameter (ID). As dynamic seals, groove design must minimize friction and wear with 8–16% compression.
JISP-Series
14 sizesThe dimensions below are identical across JIS B 2401 · JIS B 2401-1.
| Nominal | ID | CS | Use | Standard | - |
|---|---|---|---|---|---|
| P3 | 2.8 | 1.9 | Dynamic/Static | JIS B 2401 | - |
| P4 | 3.8 | 1.9 | Dynamic/Static | JIS B 2401 | - |
| P5 | 4.8 | 1.9 | Dynamic/Static | JIS B 2401 | - |
| P6 | 5.8 | 1.9 | Dynamic/Static | JIS B 2401 | - |
| P7 | 6.8 | 1.9 | Dynamic/Static | JIS B 2401 | - |
| P8 | 7.8 | 1.9 | Dynamic/Static | JIS B 2401 | - |
| P10 | 9.8 | 2.4 | Dynamic/Static | JIS B 2401 | - |
| P12 | 11.8 | 2.4 | Dynamic/Static | JIS B 2401 | - |
| P14 | 13.8 | 2.4 | Dynamic/Static | JIS B 2401 | - |
| P16 | 15.8 | 2.4 | Dynamic/Static | JIS B 2401 | - |
| P18 | 17.8 | 2.4 | Dynamic/Static | JIS B 2401 | - |
| P20 | 19.8 | 2.4 | Dynamic/Static | JIS B 2401 | - |
| P22 | 21.8 | 3.5 | Dynamic/Static | JIS B 2401 | - |
| P25 | 24.5 | 3.5 | Dynamic/Static | JIS B 2401 | - |
Key Features
- JIS B 2401 P-series numbering; cord diameters (W): 1.9/2.4/3.5/5.7/8.4 mm in 5 types
- Designed exclusively for piston (dynamic) sealing; groove diameter determined by bore ID
- NBR (general) / FKM (heat resistant) / EPDM (chemical resistant) differ in operating temperature range
Key Applications
Hydraulic cylinder pistons, pneumatic valve spools, hydraulic jacks, press ram sealing, hydraulic motor internals
FAQ
How to select P-series O-ring cross-section (W) and ID?
ID matches piston or rod diameter; cross-section is determined by groove depth (8–16% compression). Refer to JIS B 2401 spec tables.