Dynamic hydraulic rod seals use a gland around the moving rod, so their groove dimensions differ from piston-seal glands. Parker’s O-Ring Handbook gives basic dimensions for selected metric O-ring grooves used in hydraulic dynamic rod seals. The table below preserves Parker’s size numbers and dimensional labels for the selected rows.

It is a partial lookup from one handbook table. Confirm the full table, drawings, tolerances, and application before machining a gland.

Understand the backup-ring options

The b1, b2, and b3 values are the groove-width choices shown for no backup ring, one backup ring, or two backup rings. They are not three interchangeable widths. Choose the option that matches the specified seal arrangement and confirm the exact Parker drawing. A backup ring changes the space available in the gland and may be required to control extrusion under pressure.

For example, Parker number rd2-014 has d1 = 12.42 mm and d2 = 1.78 mm. Its listed width options are b1 = 2.8 mm, b2 = 4.2 mm, and b3 = 5.6 mm. The table also gives d5/d10 = 12 mm and d6 = 14.8 mm. These symbols describe particular diameters in Parker’s rod-seal drawing; use the handbook figure and tolerance labels to identify the correct surfaces on the component.

Keep the source application in view

The handbook caption limits these dimensions to selected metric sizes in hydraulic dynamic rod-seal applications. They are not a general metric O-ring standard, a complete size series, or a substitute for an engineered gland. Do not reuse them for a piston seal, a pneumatic seal, a face seal, or another seal profile. The related rows can use different cross-sections and width options, so match the Parker number and actual seal specification rather than selecting the nearest diameter.

Check clearances, tolerances, and operating conditions

Nominal dimensions alone do not establish squeeze, extrusion clearance, sealing performance, or service life. Review the tolerances specified for d5/d10 and d6, and calculate the tolerance stack between the rod, bore, gland, seal, and mating components. Check pressure, extrusion gap, motion speed, stroke, surface finish, fluid compatibility, temperature range, and elastomer compound. A groove can match the nominal table values and still be unsuitable for the actual duty.

Examine installation details as well. Lead-in chamfers and edge radii help prevent cutting or rolling the O-ring during assembly. Surface defects, spiral machining marks, contamination, or sharp edges can cause leakage or early wear. Confirm that the gland is clean and that the seal can be installed without twisting or stretching beyond the supplier’s limits.

When a backup ring is used, check the ring material, orientation, split, and fit against the pressure direction and product instructions. Confirm that the seal and backup-ring combination is available in the selected size. If the Parker table, a customer drawing, or a seal supplier’s current datasheet disagrees, resolve the discrepancy before releasing the design.

This table is a convenient cross-check for selected Parker dimensions only. It does not determine allowable pressure, leakage, friction, extrusion resistance, wear life, or suitability of a material for a fluid. Use the complete handbook and current seal-manufacturer guidance as the design reference.

Source: Parker Hannifin, O-Ring Handbook PTD5705-EN, Table 3.11, basic groove dimensions for selected metric hydraulic dynamic rod seals. Check its accompanying drawing and tolerance notes when applying any row.

For traceability, note the handbook edition, Parker number, backup-ring count, selected groove dimensions, and the revision of the component drawing. This makes later inspection or replacement work less likely to confuse a rod gland with a similar-looking piston arrangement.

Before using a row, compare the actual seal dimensions with the Parker number and cross-section, not only the nominal rod diameter. The table’s selected values cover a limited group of sizes, and omitted rows should be looked up in the complete handbook rather than interpolated. If the assembly uses a custom O-ring, a different backup-ring material, or a modified bore, request a review from the seal supplier and document the accepted dimensions.