Current position >About Us
Custom O-Ring Kit: Material Selection, Sizing, and Quotation Details
Quick Answer: A custom O-ring kit is built from the specific O-ring sizes, materials, and hardness values a maintenance team, repair shop, or OEM actually uses. CORASEALS supplies custom O-ring kits in metric and inch sizes using NBR, FKM, EPDM, HNBR, silicone, FFKM, and other materials. Send your material, ID, cross section, fluid, temperature, pressure, quantity per size, and packaging label data to receive a kit quotation.
A custom O-ring kit is different from a general assortment box. A standard kit may include many sizes the maintenance team never replaces. A custom kit contains only the sizes and compounds that match specific equipment, service intervals, or assembly operations. Each position can carry a customer part number, an equipment code, a size marking, and a hardness marking.
CORASEALS supplies custom O-ring kits for hydraulic systems, pneumatic controls, pumps, valves, cylinders, filter housings, fuel system service, chemical dosing equipment, food processing equipment, and general sealing maintenance. The kit can include one material or a mixed material set. It can be packed as a compartment box, a set of labeled bags, or a production kit for one assembly station.
Materials commonly used in custom O-ring kits
| Material | Common Kit Use | Material Notes |
|---|---|---|
| NBR | Mineral oil, hydraulic oil, general industrial service | Widely used. Good compression set. Not suitable for strong ozone or high heat. |
| FKM | Fuels, aromatic oils, many chemicals, high temperature | Good chemical resistance. Not all grades suit steam or hot water. |
| EPDM | Hot water, steam, brake fluids, outdoor exposure | Good ozone and weathering resistance. Not suitable for most mineral oil and petroleum fluids. |
| HNBR | Hydraulic oil, R134a, higher heat and abrasion | Better heat and ozone resistance than NBR. Check compound compatibility with polar fluids. |
| Silicone (VMQ) | Dry heat, low temperature, some food-contact grades | Wide temperature range but low tear strength and poor abrasion resistance. |
| FFKM | Aggressive chemicals, high temperature, difficult sealing environments | High-performance perfluoroelastomer. Used when standard elastomers fail. |
Sizing and standards
Custom O-ring kits can be built from AS568 inch sizes, ISO 3601 metric sizes, JIS B 2401 sizes, or customer-specific dimension lists. The critical dimensions are inside diameter and cross section. Many buyers also provide outside diameter to avoid confusion. State the unit and the dimension order clearly when sending the list. For example, write ID 20 mm x CS 2 mm or ID 0.750 in x CS 0.103 in.
Do not rely only on a shorthand size such as 20 x 2 without stating whether the dimension is ID x CS. Some regions and catalogs use a different order. If the groove was designed for AS568, provide the AS568 dash number. If the groove is metric, provide the ISO 3601 size or measured dimensions.
Hardness and pressure conditions
70 Shore A is a common default hardness for general O-ring kits. Higher hardness values such as 80 or 90 Shore A may be selected for high pressure or larger extrusion gaps. The final hardness must match the gland design, clearance, and operating pressure. For high-pressure applications, the kit can include backup rings in PTFE or another compatible material to reduce O-ring extrusion. The need for backup rings depends on pressure, gland clearance, and O-ring hardness.
The fluid and temperature range control the material choice more than