For optimum seal performance consideration must also be given to housing:
- Material
- Roughness
- Tolerance
Housing material
Steel and cast iron provide a good surface for both rubber and metal O.D. seals. For soft alloy (aluminum) housings, seals with rubber O.D. provide a better sealing capacity.
Housing roughness
The housing inside diameter roughness is 10 µ inch Ra or 2.5 µm Ra for metal O.D. seals and 150 µ inch or 3.75 µm Ra for rubber covered O.D.
Housing Tolerance
Housing tolerances are in tables to the right: |
Bore diameter D2(inch) |
Bore tolerance |
up to 3.000 |
+/- 0.001 |
3.001 to 6.000 |
+/- 0.0015 |
6.001 to 10.000 |
+/- 0.002 |
10.001 to 20.000 |
+0.002 / -0.004 |
20.001 to 40.000 |
+0.002 / -0.006 |
40.001 to 60.000 |
+0.002 / -0.010 |
Bore diameter D2 (mm) |
Bore tolerance
(ISO/H8) |
Over 6 to 10 |
+0.022 / -0.000 |
Over 10 to 18 |
+0.027 / -0.000 |
Over 18 to 30 |
+0.033 / -0.000 |
Over 30 to 50 |
+0.039 / -0.000 |
Over 50 to 80 |
+0.046 / -0.000 |
Over 80 to 120 |
+0.054 / -0.000 |
Over 120 to 180 |
+0.063 / -0.000 |
Over 180 to 250 |
+0.072 / -0.000 |
Over 250 to 315 |
+0.081 / -0.000 |
Over 315 to 400 |
+0.089 / -0.000 |
Over 400 to 500 |
+0.097 / -0.000 |
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