1. How do I tell how much PSI an O-Ring can handle?
There is no single PSI rating for an O-Ring. Pressure capability depends on the entire sealing system. This includes the extrusion gap, durometer, temperature, fluid, and whether backup rings are used.
For applications around 2000 PSI, a 90 durometer O-Ring with backup rings and a tight clearance gap is the most reliable approach. Static seals can handle more pressure than dynamic ones.
2. What is the minimum order quantity for O-Rings?
Stock O-Rings are available in small quantities.
Custom O-Rings typically require a minimum of 1,000 to 5,000 pieces depending on size and compound. This is due to factory production requirements.
3. How much does shipping cost?
Shipping costs are based on weight, destination, and delivery speed.
Real-time shipping rates allow you to compare options and select the best balance of cost and delivery time.
4. Can I use my own UPS or FedEx account?
Yes.
Using your own carrier account for freight collect often reduces shipping cost, especially for repeat or bulk orders.
5. How fast do O-Rings ship?
In-stock orders that are ship complete typically ship the same day or next business day.
Custom and backordered items usually ship in 3 to 4 weeks domestically, and 12 to 16 weeks for production runs.
6. What is the shelf life of an O-Ring?
Shelf life depends on the material and storage conditions.
- Buna-N (Nitrile): 15 years
- FKM (Viton®): Unlimited
- EPDM: Unlimited
- Silicone: Unlimited
- FFKM (Simriz): Unlimited
Store O-Rings in a cool, dark, dry environment away from ozone and UV exposure for maximum life.
Also check here: O-Ring Handbook
7. What material should I use for my application?
Material selection depends on fluid, temperature, and pressure.
- Buna-N 70: General purpose oil and fuel resistance
- Buna-N 90: Higher pressure and extrusion resistance
- Viton 75: High heat and chemical resistance
- Viton ETP: Improved chemical and amine resistance
- FFKM Simriz: Extreme chemical and temperature environments
- EPDM: Water, steam, and glycol resistance
- Silicone: Food grade and extreme temperature flexibility
Choosing the right material prevents most seal failures.
8. What durometer should I choose?
70 durometer is standard for most applications.
90 durometer is better for high pressure, extrusion resistance, and tighter sealing control.
Harder materials resist deformation but require better gland design.
9. Do I need a backup ring?
If pressure exceeds 1500 PSI or there is a noticeable clearance gap, backup rings are recommended.
They prevent extrusion and extend O-Ring life, especially in hydraulic systems.
10. Can I reuse an O-Ring?
In most cases, no.
Once compressed and exposed to heat or chemicals, the material properties change. Replacing the O-Ring reduces the risk of leaks and failure.
11. What causes O-Rings to fail?
Common failure causes include:
- Extrusion from high pressure
- Chemical incompatibility
- Excessive heat
- Incorrect sizing
- Poor gland design
Proper material selection and installation prevent most issues.
12. What temperature can O-Rings handle?
Temperature limits vary by material:
- Buna-N: -40°F to 250°F
- Viton: up to 400°F
- EPDM: excellent for hot water and steam
- Silicone: wide range from very low to high temperatures
- FFKM: extreme temperature resistance
Matching temperature range is critical for long-term performance.
13. Do O-Rings work with chemicals?
Yes, but only if the material is compatible with the chemical.
- Buna-N 70 and 90: Good for petroleum oils, poor for strong chemicals
- Viton 75: Excellent for fuels, solvents, and many chemicals
- Viton ETP: Improved resistance to aggressive chemicals and amines
- FFKM Simriz: Near universal chemical resistance, ideal for harsh environments
- EPDM: Excellent for water, steam, and polar chemicals, not for oils
- Silicone: Moderate chemical resistance, best for food and temperature extremes
Using the wrong material is the fastest way to cause seal failure.
14. Can O-Rings handle vacuum applications?
Yes.
O-Rings perform well in vacuum when properly sized and installed. Low outgassing materials like FKM and FFKM are preferred.
15. What is the best O-Ring for hydraulic systems?
Buna-N 90 durometer is the most common choice.
For higher temperatures or aggressive fluids, Viton may be used. Backup rings are recommended for higher pressure.
16. Are O-Rings food safe?
Only specific compounds meet food-grade requirements.
Silicone and EPDM are commonly used when FDA compliance is required.
17. Can I get O-Rings with certifications?
Yes.
Certifications include FDA, NSF-61, 3-A sanitary, and USP Class VI for regulated industries. Factory C of C are included with mil-spec and aerospec O-Rings only. All other O-Rings come with the O-Ring house C of C as they are commercial off-the-shelf goods.
18. What is PTFE coating on an O-Ring?
PTFE coating reduces friction and sticking.
It improves installation and performance in dynamic applications.
19. What is the HS Tariff Code for O-Rings?
HS Code 40169390 is commonly used for rubber O-Rings and seals in international trade.
20. Can O-Rings be custom made?
Yes.
Custom sizes and compounds are available, but they typically require tooling and minimum production quantities.
21. What is the lead time for custom O-Rings?
Standard lead times are 12 to 16 weeks for production runs.
Planning ahead helps avoid downtime and rush costs.
22. What is extrusion in an O-Ring?
Extrusion occurs when the O-Ring is forced into a clearance gap under pressure.
This leads to damage called nibbling. Higher durometer and backup rings help prevent this.
23. What is compression set?
Compression set is the loss of elasticity after the O-Ring is compressed over time.
Materials like FKM and FFKM typically perform better in high heat environments.
24. How should O-Rings be stored?
Store O-Rings in sealed bags in a cool, dry, and dark environment.
Avoid ozone sources like electric motors and direct sunlight.
25. What is the fastest way to order O-Rings?
Ordering online with real-time stock and pricing is the fastest method.
It reduces delays and ensures accurate order processing.
Sizing and Standards
26. What is AS568 O-Ring sizing?
AS568 is the standard inch sizing system used in the United States.
It defines the inside diameter and cross section so O-Rings are interchangeable across manufacturers.
27. How do I measure an O-Ring correctly?
To measure an O-Ring correctly, you only need two dimensions: the inside diameter (ID) and the cross section (CS), which is the thickness of the rubber. Start by placing the O-Ring on a flat surface and letting it relax. Do not stretch it or hold it in the air. Measure the cross section first using calipers, lightly closing them on the rubber without squeezing, since compression will give you a false reading. Then measure the inside diameter straight across the center from inner edge to inner edge. If the O-Ring has been used, it may be slightly stretched, so take a couple of readings and match to the closest standard size rather than expecting perfect precision.
The most common mistake is measuring the outside diameter or trying to follow the centerline, which will not give you a usable size. Standard O-Rings are defined by ID and cross section only, so getting those two numbers right is what matters. If your measurements do not match common inch sizes, there is a good chance you are working with a metric O-Ring. For a faster and more consistent method, the Olypsys® phone measurement app allows you to place the O-Ring on a grid, take a photo, and have the app calculate both ID and cross section automatically. This removes guesswork, improves accuracy, and helps you get to the correct size the first time, which saves time and avoids ordering the wrong part.
28. How do I convert metric O-Ring sizes?
Metric O-Rings are defined in millimeters using ID and cross section.
To convert, match both dimensions as closely as possible between inch and metric standards.
29. What are military or mil-spec O-Rings?
Mil-spec O-Rings meet strict military standards for material and performance.
These are often required in aerospace and defense applications.
30. How do I know if I have the right O-Ring size?
The O-Ring should fit with slight stretch on the ID and proper squeeze in the groove.
If it is too loose or too tight, it will not seal correctly. Using standard size charts ensures proper fit.