Identifying an oil seal can be tricky, especially if only inch measurements are printed on its surface, so here is a little guide that will help you get started quickly and smoothly.
Oil Seal with Metric System Measurements
When the dimensions in the metric system are printed on the oil seal, the work is quite simple, for example 20 47 7 indicates that the internal hole measurement is 20 mm, the total (external) diameter measurement is 47 mm and the height ( intended in thickness) is 7 mm, some types of seal rings may have several types of acronyms, each different depending on the manufacturer, but the essential information you need are the measurements, material and structural characteristics of the oil seal .
Oil seals with imperial system measurements (inches)
When the measurements are printed on the retainer with the imperial system things get more complicated as the numbers on the retainer are in fractions and always start first with the external diameter, for example 300 212 37 this indicates that the dimensions of the retainers are 2.1/8 “in, 3” outside and 3/8 wide, below is a table to help you convert measurements from inches to millimeters:
| Inches | Mm |
| 01/16 | 0.06 |
| 1/8 | 0.12 |
| 03/16 | 0.18 |
| 1/4 | 0.25 |
| 05/16 | 0.31 |
| 3/8 | 0.37 |
| 7/16 | 0.43 |
| 1/2 | 0.50 |
| 16/09 | 0.56 |
| 5/8 | 0.62 |
| 11/16 | 0.68 |
| 3/4 | 0.75 |
| 13/16 | 0.81 |
| 7/8 | 0.87 |
| 15/16 | 0.93 |
| 1 | 1.00 |
To help you understand how the conversion table for inch oil seals to metric seals works, here are some sample references:
(remember the first number is always the outer diameter)
137 62 25 = 5/8″ inside x 1.3/8″ outside x 1/4″ wide
187 125 25 = 1.1/4″ inside x 1.7/8″ outside x 1/4” wide
150 250 37 = 1.1/2″ x inner 2.1/2″ x outer 3/8″ wide
Finally, remember that in our store there is a category of inch seals, all available in stock and ready for shipping 24 hours a day throughout Italy and Europe, which we have already converted to the metric system. Consult this guide and find the corresponding retainer. If you have trouble identifying the correct oil seal, please don't hesitate to contact us.
