O-ring selection made easy


Parker Hannifin’s O-Ring Selector is an engineering tool which offers O-ring material and size selection combined in one software package. Both are interlinked, thus helping ensure the best possible combination of the calculated O-ring size and material choice. The O-Ring Selector covers both imperial and metric standards.

Parker’s O-Ring Selector combines O-ring material and size selection in one software tool.

The program lets users find the most suitable sealing material by specifying the minimum and maximum operating temperature, and the desired polymer group or seal hardness. An advanced material selector looks at service conditions in even greater detail. For instance, users can select and combine the fluids which are relevant to an application by using the filter by fluid compatibility search bar. This search and filter function searches a database of more than 2,500 different materials.

The hardware configuration section provides options on different sealing cases such as radial piston or rod sealing, axial sealing with internal or external pressure. After selecting a material that fits the sealing application, the size selector can calculate the O-ring dimensions and tolerances, considering even thermal expansion and volume swelling of the sealing element. The parameter dashboard in the results section will immediately show if the selected O-ring size is suitable for your application.

For a quick run-through, clicking on the “Start Imperial Version” tab takes the user into the service conditions and material selector. Note that some of these choices affect the sizing selector, so it is best to start here.

The user first specifies the operating temperature, which for the selector can range from -80° to 575°F. For instance, entering an operating temperature range of -20° to 120°F takes you to the seal material selector. This first lists acceptable polymers for this range, including ABS, butyl rubber, ethylene acrylate, ethylene propylene rubber, fluorocarbon and fluorosilicone, hydrogenated nitrile, Neoprene, silicone, and Ultra FFKM.

Selecting a FVMG fluorosilicone, for example, then offers a range of acceptable of user-select seal hardnesses. An advance material selector section lets users filter by fluid compatibility, noting that products must have at least a fair compatibility with the fluid. It also cautions that when in question, always test the product for suitable fluid compatibility.

A wide range of hydraulic and other fluids, air at various temperatures, and lubricants, as well as acids, caustics and many other chemicals and solvents are listed. Choosing, for example, Esso Univis No. 40 hydraulic oil then brings up applicable certifications like MIL/Aero. It also lists possible material colors and whether the seal is internally lubed.

The user is then prompted to the size selector to determine the correct dimensions and tolerances for the O-ring and hardware configuration. One next selects the sealing case: radial piston seal or rod seal; or axial with internal or external pressure. It then asks whether the application is static or dynamic, and whether thermal expansion and volume swelling are issues. Users can opt to select the piston and bore material, including aluminum, copper, steel, stainless steel and various plastics.

Then, in the sizing section, the selector shows possible dimensions for the O-ring ID and cross section and, say for a radial piston seal, dimensions for the piston, groove and bore. Users can also note the number of back up rings, if any.

A size-search button helps narrow the possible options, or users can enter the O-ring size code. For example, entering a 2-425 code displays nominal dimensions and tolerances for bore and piston diameters, and groove diameter, width and radius.

Lastly, it displays results, including degree of compression, extrusion gaps, seal stretch or compression, gland fill, and total deformation force—an approximate value of the sealing force acting on the hardware. It’s based on the seal hardness, dimensions and the amount of compression. Results are listed as: recommended, with caution, or in need of critical review.

Recommendations on application design and material selection are based on available technical data and are offered as suggestions only, Parker cautions. Each user should make his own tests to determine the suitability for his own particular use. Users can save the calculations, download a PDF document, or click a link to the specific product page for additional technical details. The selector also lists contact info to reach a Parker application engineer.

Parker Hannifin


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