Small, Simple & Significant: Your Guide to Everything O-Ring

Over the last few centuries, the world has advanced and moved towards an industrialised and machine-oriented way of doing things. As such, demand for simple yet crucial parts that are essential for a machine’s functioning has risen, and O-rings are a major part of that category.

If you have had issues with leakage, whether liquid or gas, or you are looking to avoid it altogether, O-rings and seals are the solution. But what is an O-ring, and is there a specific one you should get? At ReFast, we have all the answers you need.

What Is an O-Ring?

An O-ring is a torus-shaped ring that is used to prevent liquids and gases from leaking, by providing a soft material to fill in a clearance gap. Rubber O-rings were first introduced to the market in the 20th century, but are still widely used because of their function, simplicity, and economical and efficient design.

Though these sealing rings are simple, there can be significant and expensive repercussions if you get them wrong, and fail to consider factors like material compounds, temperature and groove design. O-rings are used across virtually every industry in many ways, like plumbing, engines, food and beverage preparation, aircrafts and much more, so choosing the right O-ring is key.

How Are O-Rings Measured?

When it comes to the size of an O-ring, it can follow an imperial standard or a metric standard. Common imperial standards are denoted by BS (British Standard) or AS (American Aerospace Standard). On the other hand, there are a few metric standards used globally, like Japanese, German, French and Italian.

In Australia, the Japanese metric standard is most common and denoted by JIS (Japanese Industry Standard). O-ring sizes in Australia can also be based on a non-standard metric, which is just as common as JIS, if not more common.

Under the non-standard metric, measurements are rounded up, like 30x3, as opposed to 29.4x3.1 in JIS. If you want to size an O-ring, the best way is to measure the CS (cross-section) and the ID (inner diameter). To do this, use a calliper, as it provides the accuracy you need to identify your O-ring size.

Get to Know the Types of O-Rings

Based on their application, O-rings are available in different material compounds and compound hardness. Rubber is the most common material used for making these sealing rings, and different compounds of rubber serve different purposes.

The hardness of the rubber is measured on a Shore A Durometer, and the higher the ‘Duro’, the harder the rubber. Nitrile, also known as NBR, is the most common type of rubber compound used to manufacture O-rings. NBR is available in two types: NBR 70 and NBR 90. NBR 70 is the most prevalent industrial O-ring and is compatible with most mineral-based hydraulic fluids.

NBR 90 is much harder, and, so, better suited for a high-pressure O-ring. An alternative to NBR is Viton 75, which is made of fluorocarbon rubber. This makes it better equipped to handle higher temperatures and provides better resistance against strong chemicals than most NBR O-rings. You can also find O-rings made of silicone, metal or stainless steel, but rubber compounds still remain the most used.

Choose the Right O-Ring at ReFast

As simple as they seem, O-rings provide excellent utility, and a lot of machines and processes would struggle without these sealing rings. At ReFast, we are industrial equipment suppliers, and, so, understand the differences between types of O-rings, and which ones would be the best for you. Whether you need them for industrial purposes, or small DIY projects, we have you covered with the wide range we offer, across sizes, materials and styles, all at reasonable prices. If you are looking for trustworthy O-ring suppliers in Australia, shop online at ReFast, or contact us at (03) 9583 9433 to speak to one of our friendly staff.