Having a Better Understanding of O Rings
ShareIf your plumber, mechanic or appliance/equipment repair specialist informs you that he or she needs to buy an O ring because the one you have is damaged, this is what the specialist is talking about:
What Is an O Ring?
An O ring is a kind of seal that is applied to joints of various pieces of equipment. It is shaped like an O or a ring, hence the name O ring. It is placed in a groove located on one of the machines or parts to be joined and then compressed between the two parts. O rings help make a joint tightly sealed in such a way that vapour and fluid cannot leak. They also hold pressure inside the equipment without letting any air or debris pass through, meaning they can be used as a safety mechanism as well.
Two Main Categories of O Rings
You can either come across static or dynamic O rings. Static O rings are used for parts that are fixed (parts that don't move about; stationery machines), while dynamic O rings are used for parts that move about.
Sub-Categories Under Dynamic and Static O Rings
Of course, there are different types of machines that handle different fluids, temperatures, pH levels, pressures, environmental factors, etc. Just because an O ring is made for either fixed or mobile applications does not mean that, for example, one fixed-application O ring can be used for different pieces of equipment. You have to think about its size and material composition. Each material can handle different temperature, pH and pressure levels.
What does this mean? You will come across dynamic and static O rings, and then under each of these categories, you will find different O rings of different sizes and material compositions.
What Are the Different Materials You Might Come Across?
The most common O rings include:
• Viton: Suitable for acids, petroleum oils, esters, amines, etc. They can handle temperatures between -29°C to 204°C.
• Nitrile/Buna-N: Suitable for water and petroleum oils. Do not use them with ketones or brake fluid. They can handle temperatures between -40°C to 121°C.
• Neoprene: Seals refrigerants. It can handle temperatures between -43° to 107°C.
• Silicon: Suitable for steam, water and petroleum fluids. They are also most suitable for fixed applications because they can get damaged easily. It can handle temperatures between -60°C to 232°C.
• Ethylene Propylene Rubber (EPR)/(EPDM): Can be used for steam, water, corrosive hydraulic fluid, brake fluid, silicone oils, alcohols, chemicals, etc. They can handle temperatures between -51° to 150°C.
• Polyurethane: Used for cylinders, valves, pneumatic tools and hydraulic fittings. They can handle temperatures between -51° to 107°C.