Company Profile

Custom Pneumatic Seal Selection, Sizing, and RFQ Data

Quick Answer: A custom pneumatic seal is specified when a cylinder uses a non-standard bore, rod diameter, groove width, or operating condition that catalog seals cannot cover. Send CORASEALS the bore diameter, rod diameter, groove dimensions, operating pressure, temperature, media, and seal profile. We will check the seal section, material, and tolerance before quotation.

Custom pneumatic seals are used in pneumatic cylinders, valve actuators, factory automation equipment, and air tool repair. Standard pneumatic seal catalogs cover many metric and inch sizes, but real cylinders can be worn, modified, imported, or built to non-standard dimensions. A custom pneumatic seal allows the seal profile and material to match the actual cylinder hardware.

CORASEALS supplies custom pneumatic seal types as replacement parts and as components for cylinder service programs. The main products include pneumatic rod seals, pneumatic piston seals, pneumatic wiper seals, O-rings, and custom machined lip seals. We focus on seal geometry first, not only on part numbers.

When a Custom Pneumatic Seal Is Required

A custom pneumatic seal may be needed in the following situations:

• Metric cylinder dimensions do not match common ISO or DIN pneumatic cylinder sizes.
• Inch bores, rods, or grooves require ID, OD, and width conversion.
• The original seal compound must change from NBR to FKM or another material.
• The groove is shallow, wide, worn, or not listed in a standard seal catalog.
• A special lip shape, wiper geometry, or non-standard section is required.
• A continuous production part is needed with controlled dimensions and packaging.

In these cases, a standard pneumatic seal may fit loosely, pinch, or wear early. The custom option matches the seal section to the actual cylinder hardware.

Pneumatic Seal Profiles for Custom Production

Pneumatic rod seals keep air inside the cylinder while the rod moves. They are often single-acting lip seals or compact U-cup profiles. The rod seal must operate with low friction and tolerate some side load if the rod alignment is not perfect.

Pneumatic piston seals are installed on the piston and seal between the piston OD and the bore. They commonly use low-friction NBR or polyurethane lip profiles. The groove width is critical because a narrow groove can pinch the seal and a wide groove can allow extrusion.

Pneumatic wiper seals remove dust and moisture from the rod during retraction. They protect the rod seal from contamination. In dusty or dirty factory air, a custom wiper may need a different lip angle or a harder compound.

O-rings are used for static sealing on end caps, sleeves, and valve bodies in pneumatic systems. Custom O-ring sizes can be produced for non-standard inside diameter and cross section requirements.

Material Selection for Custom Pneumatic Seals

NBR and polyurethane are common for general pneumatic cylinder service. FKM is specified when the seal sees higher temperatures or aggressive chemicals. EPDM is not suitable for most mineral oil lubricated air systems because petroleum oil can degrade EPDM. Silicone is rarely used for dynamic pneumatic lip seals because of its low tear strength, but it can be used in some static or low-load applications.

Some polyurethane compounds can be sensitive to hot water and hydrolysis. If the air system has high condensation, washdown cleaning, or chemical exposure, the compound must be checked. Do not choose a material only by color or hardness. Provide the air temperature range, lubrication condition, cleaning chemicals, and required Shore A hardness.

Dimensions and Measurement Data Required

For a custom pneumatic seal quotation, send the following information:

• Bore diameter
• Rod dia