Hey there! As a supplier of NBR 90 O Rings, I often get asked about the standard specifications of these little but crucial components. So, I thought I'd write this blog to share some insights.
First off, let's talk about what NBR 90 means. NBR stands for Nitrile Butadiene Rubber, which is a synthetic rubber known for its excellent resistance to oil, fuel, and other petroleum - based fluids. The number 90 refers to the Shore A hardness of the O - ring. Shore A hardness is a measure of the material's resistance to indentation. A Shore A hardness of 90 means the NBR O - ring is relatively hard. This hardness gives it certain advantages, like better resistance to extrusion under high pressures.
Dimensions
One of the most important aspects of the standard specification is the dimension. O - rings come in a wide range of sizes, and the NBR 90 O Rings are no exception. The key dimensions include the inner diameter (ID), outer diameter (OD), and cross - section diameter (CS).
The inner diameter is the measurement of the hole in the middle of the O - ring. It's crucial because it needs to fit precisely around the shaft or the component it's supposed to seal. For example, if you're using an NBR 90 O - ring in a hydraulic system, the ID must match the diameter of the piston rod. A wrong ID can lead to leaks, which can be a big problem in industrial applications.
The outer diameter is the measurement from one outer edge of the O - ring to the opposite outer edge. It determines how well the O - ring will fit into the housing or the groove where it's installed. If the OD is too large, it may not fit properly, and if it's too small, it won't create an effective seal.
The cross - section diameter is the thickness of the O - ring. A consistent CS is essential for a good seal. If the CS varies, it can cause uneven pressure distribution, leading to leakage. Standard sizes for CS can range from a few millimeters to several centimeters, depending on the application. You can find more details about different O - ring sizes and their applications on the Car O Ring page.
Tolerances
Tolerances are also a part of the standard specification. Tolerances define the acceptable range of variation in the dimensions of the O - ring. For example, if the specified ID of an NBR 90 O - ring is 20 mm, there will be a tolerance associated with it, say ±0.1 mm. This means the actual ID of the O - ring can be anywhere between 19.9 mm and 20.1 mm and still be considered within the standard.
Tolerances are important because they ensure the interchangeability of O - rings. If you're replacing an O - ring in a machine, you want to be sure that a new O - ring with the same specified dimensions will fit and work properly. Tighter tolerances are usually required for more precise applications, such as in aerospace or medical devices.
Material Properties
As mentioned earlier, NBR 90 O - rings are made of Nitrile Butadiene Rubber with a Shore A hardness of 90. This material has several properties that make it suitable for various applications.
Chemical Resistance
NBR is highly resistant to oil, fuel, and other petroleum - based products. This makes it a popular choice in automotive and industrial applications where contact with these substances is common. For example, in a car engine, NBR 90 O - rings can be used to seal fuel lines, preventing fuel leaks. It also has good resistance to some chemicals like acids and alkalis, although the resistance may vary depending on the concentration and temperature of the chemicals.
Temperature Resistance
The temperature resistance of NBR 90 O - rings is another important factor. Generally, NBR can withstand temperatures ranging from - 40°C to 120°C. However, the performance may degrade at the extreme ends of this range. At low temperatures, the rubber may become brittle, losing its elasticity and sealing ability. At high temperatures, it may start to break down, causing leaks. You can learn more about temperature resistance of different O - ring materials on the O Ring Silicone Temperature page.
Compression Set
Compression set is the ability of the O - ring to return to its original shape after being compressed. A low compression set is desirable because it means the O - ring will maintain its sealing force over time. NBR 90 O - rings typically have a relatively low compression set, which is why they can provide long - lasting seals in many applications.
Applications
NBR 90 O - rings are used in a wide variety of applications.
Automotive Industry
In the automotive industry, they are used in engines, transmissions, and fuel systems. For example, they can be found in oil filters, fuel injectors, and hydraulic brake systems. Their resistance to oil and fuel makes them ideal for these applications.
Industrial Machinery
In industrial machinery, NBR 90 O - rings are used in hydraulic systems, pneumatic systems, and pumps. They help to prevent fluid leaks and maintain the efficiency of the machinery. For instance, in a hydraulic press, the O - rings ensure that the hydraulic fluid is contained within the system, allowing the press to operate smoothly.
Aerospace
Although aerospace applications often require more specialized materials, NBR 90 O - rings can still be used in some non - critical areas where their properties meet the requirements. They can be used in some ground support equipment or in less demanding parts of an aircraft.
Comparison with Other O - Rings
It's also interesting to compare NBR 90 O - rings with other types of O - rings, like O Ring Fkm 75. FKM (Fluoroelastomer) O - rings, such as the FKM 75 ones, have better chemical and temperature resistance compared to NBR. They can withstand higher temperatures and are more resistant to a wider range of chemicals. However, they are also more expensive.
NBR 90 O - rings, on the other hand, are more cost - effective and are a great choice for applications where the chemical and temperature requirements are not as extreme. So, the choice between NBR 90 and FKM 75 O - rings depends on the specific needs of the application.
Quality Control
As a supplier, we have strict quality control measures in place to ensure that our NBR 90 O - rings meet the standard specifications. We use advanced manufacturing techniques and testing equipment to check the dimensions, material properties, and performance of the O - rings.
We conduct dimensional inspections using precision measuring tools to make sure the O - rings are within the specified tolerances. We also test the material properties, such as hardness, chemical resistance, and compression set, to ensure they meet the required standards.
Conclusion
In conclusion, the standard specification of NBR 90 O - rings includes dimensions, tolerances, and material properties. These O - rings are made of Nitrile Butadiene Rubber with a Shore A hardness of 90, which gives them good resistance to oil, fuel, and other chemicals. They are used in a wide range of applications, from automotive to industrial.
If you're in the market for high - quality NBR 90 O - rings, we're here to help. We can provide you with O - rings that meet the standard specifications and are suitable for your specific needs. Whether you need a small quantity for a DIY project or a large order for an industrial application, we've got you covered. So, don't hesitate to reach out and start a conversation about your NBR 90 O - ring requirements. Let's work together to find the best solution for your sealing needs.
References
- "Handbook of O - Ring Technology"
- "Rubber Materials and Their Applications"