Step 1: Define the medium the seal will contact

The supplier's product FAQ says that choosing a rubber material starts with the medium the seal will contact, such as oil, chemicals or seawater. After that, look at the application temperature, whether the seal is dynamic or static, and whether it is a surface seal or a shaft seal.

Send your medium details to the supplier and ask for a material recommendation. The supplier offers guidance on choosing rubber based on medium contact and temperature. It also lists NBR, EPDM, FKM, HNBR and fluorosilicone among its materials, so if silicone doesn't fit your medium, you can ask about another compound.

Step 2: Confirm the operating temperature

The two silicone O-ring product pages state different temperature figures:

Because the figures differ, and the first page's lower limit appears without a sign, confirm the rated temperature range for your specific compound in writing before you approve a design. This matters most for low-temperature use. In its own material comparison, the supplier lists silicone (VMQ) at -50 °C to 230 °C and FKM at -20 °C to 320 °C. If your process runs above the confirmed silicone rating, raise it with the supplier.

Step 3: Specify dimensions accurately

One product page states a size range of OD 1 mm to 993 mm and a wire (cross-section) diameter of 1.0 mm to 8.0 mm. If your dimensions fall outside these ranges, confirm feasibility before you plan around the part.

You can supply dimensions in two ways:

• Drawing-based: send a drawing with the inner or outer diameter, cross-section and tolerances.
• Sample-based: the supplier states that it measures physical samples with a professional optical projector and creates a 3D drawing for your approval before production.

Approve the drawing before tooling starts. Lead times depend on quantity and mold availability.

Step 4: Match hardness and motion to pressure

One page fixes hardness at 50-55 Shore A. The other describes hardness as adjustable based on pressure. If your application has notable pressure or dynamic movement, give the supplier the pressure level, whether the seal is static or dynamic, and the gland design. Then ask for a recommended hardness instead of assuming a default.

Step 5: Consider color, grade and documentation

• Color: multiple colors are offered on one product page to make part identification and maintenance easier. The VMQ O-ring and gasket page lists black.
• Grade: food-grade and industrial silicone options are listed. If your application involves food or medical contact, ask for the specific compliance documents for the compound you are buying. Don't rely on the grade label alone.
• Quality documents: the product pages mention ISO 9001 and TS 16949. Ask for current certificate copies and inspection records as part of supplier qualification.

When this recommendation may not apply

Silicone O-rings may not be the best choice if your medium is not compatible with silicone, if your temperature range is outside the confirmed rating, or if your dimensions are outside the stated size range. In those cases, ask about other materials or a separate custom design. For other rubber O-ring options, see Custom Rubber ORings and confirm the details with the supplier.

Buyer checklist for Custom Sealing Solutions

1. Contact medium (oil, chemicals, seawater, food or other)
2. Minimum and maximum operating temperature
3. Static or dynamic seal; surface or shaft seal
4. Pressure level and preferred hardness
5. Dimensions from a drawing, or a physical sample for measurement
6. Color and grade (food grade or industrial)
7. Required documents, inspection records and packaging (one page lists PE bag, carton and pallet)

Price, delivery schedule and compliance documents should be confirmed in a formal quotation for your specific part.