NBR O-Rings for Fluid Power Systems: 70 Shore A Buna-N Seals for Leak-Proof

Product Specification

The 70 Shore A Buna-N o ring is the most widely utilized sealing solution in the fluid power industry. Often referred to as Nitrile or NBR (Nitrile Butadiene Rubber), this material is specifically engineered to provide an airtight and watertight seal in environments dominated by oils and fuels. The 70 Shore A hardness rating represents the standard industrial grade, offering an ideal balance between flexibility for easy installation and firmness to resist extrusion under pressure. These rubber o rings are critical components in maintaining the integrity of hydraulic systems, preventing costly leaks and ensuring the safety of high pressure machinery in demanding settings like oil and gas rigs.

Nitrile Butadiene Rubber (NBR) is a synthetic elastomer valued for its exceptional resistance to petroleum based fluids. Choosing the right material depends on the operating environment:

• NBR vs. EPDM: While EPDM is superior for outdoor weather and steam, it fails quickly when exposed to oil. NBR is the primary choice for any application involving grease, hydraulic fluid, or fuel.

• NBR vs. Fluoroelastomer (FKM): Fluoroelastomers can handle higher temperatures and harsher chemicals than NBR. However, NBR is more cost effective and provides better low temperature flexibility, making it the standard for general hydraulic and pneumatic applications.

• NBR vs. Silicone: Silicone offers a wider temperature range but has very poor tear strength and abrasion resistance. NBR is much tougher and more durable for mechanical and dynamic sealing where friction is present.

	Material: Nitrile Butadiene Rubber (NBR / Buna-N)
	Color: Black
	Hardness: Typically 70 Shore A (Standard) - 90 Shore A (High Pressure)
	Tensile Strength: 14 to 18 MPa

Welcome to Shanghai Qinuo Industry. Backed by our state-of-the-art, ISO 9001:2015 certified manufacturing base—Jiangsu Ruowei Energy Technology—we stand at the forefront of delivering high-performance rubber solutions.

Our production base in Nantong is equipped with over 30 advanced vulcanizing machines, delivering a monthly capacity of 20 tons (40,000 lbs) across 20+ product categories. Strategically located near Shanghai’s major air and sea ports, we ensure streamlined logistics and reliable global delivery.

Under our registered brands Royal Way® and SHQN®, we remain committed to our core principle: "Quality for Stability, Innovation for Progress." We provide the energy sector with durable, precision-engineered sealing solutions you can depend on.

Question 1: Why is 70 Shore A the most common hardness for NBR seals?
Answer: 70 Shore A is considered the universal hardness because it is soft enough to seal against slightly rough surfaces but hard enough to withstand the pressures found in most standard hydraulic and pneumatic systems without tearing.

Question 2: Can I use Buna-N O-rings for outdoor applications?
Answer: While Buna-N can be used outdoors, it is susceptible to ozone cracking and UV degradation over time. If your application is primarily outdoor infrastructure with no oil contact, EPDM is a better choice. If oil is present, NBR is necessary but may require shielding from direct sunlight.

Question 3: Are these O-rings resistant to gasoline?
Answer: Yes, NBR is highly resistant to gasoline and many types of fuel. However, for fuels with high ethanol content or for extremely high temperature fuel systems, specialized grades or Fluoroelastomers may be required.

Question 4: What causes a Buna-N O-ring to fail in a hydraulic system?
Answer: The most common causes are "compression set" (the ring loses its bounce after excessive heat), abrasion from moving parts, or using an incompatible fluid that causes the rubber to swell or shrink.

Question 5: Is Buna-N the same as Nitrile?
Answer: Yes. Buna-N, Nitrile, and NBR all refer to the same synthetic elastomer: Nitrile Butadiene Rubber. These names are used interchangeably across the industry.