Types of O-Rings and How They Are Used in Water Treatment Systems

Posted by
John Woodard on February 27, 2024

O-rings are by no means a new technology, but they are still used everywhere a reliable seal is needed between two or more components. Their inexpensiveness, effectiveness, and versatility make O-rings capable of sealing in systems that transport many different liquids and gases. Because they are installed in so many applications, O-rings offer a variety of seal types based on the material they utilize. In this article, you can learn about common types of O-rings used in various applications.

How do O-rings work?

O-rings are gaskets with a round cross-section that can withstand extreme temperatures and pressures that a normal gasket cannot. When installed correctly, an O-ring becomes compressed between at least two components. While compressed, greater pressure on one side of the O-ring forces the O-ring to fill in the side with less pressure, creating a tight seal. O-rings can be made from a plethora of different materials, each suited to a desired application. For example, an O-ring used in a system that pumps toxic chemicals must be able to withstand this chemical at various pressures and temperatures.

How long do O-rings last?

If the correct type of O-ring is used for an application and is installed correctly, it can last anywhere from a year to much longer, depending on the application it is used for. There is no definitive measure on how long an O-ring will last, so always consult your specific system to determine how often your O-rings should be replaced. Be wary of signs of O-ring damage, such as system leaks, inefficiencies, or visual and physical changes to the O-ring itself. If you notice any of these signs, your O-ring should be replaced immediately.

How often should I inspect my O-rings?

O-rings should be inspected at least once every few years or whenever you detect there may be a problem. When reinstalling your O-ring after inspection, seating it correctly is key to maintaining the health of your system.

How to inspect an O-ring

You can inspect your O-ring without removing it from your system, but you will not be able to see its entire surface area. To inspect an O-ring fully, follow these steps:

  1. Remove your O-ring from the system.
  2. Use a lint-free cloth to remove any liquids from the O-ring’s surface.
  3. Check the O-ring for discoloration, signs of wear, particles, debris, or anything else that might disturb the performance of the ring. If you notice any disturbances, replace the O-ring with a new one.
  4. Add lubricant to the O-ring before reinserting it. For silicone O-rings, you can use silicone lubricant grease. Use only enough lubricant to give the O-ring a light coating.
  5. Install the O-ring into the appropriate location, ensuring that no debris has found its way to the install location or on the surface of the O-ring.

What are common types of O-rings?

O-rings can be made from an abundance of materials, each of which are suited to a particular temperature, chemical, and pressure tolerance. Below are six of the most common materials used for O-rings, including nitrile, silicone, Viton™, EPDM, PFA, and FEP.

O-ring types

Nitrile O-rings

Nitrile, also known as Buna-N, is a synthetic rubber used in O-rings that are useful in a wide variety of applications. Boasting a temperature range of -40°F to 250°F (-40°C to 121°C) and resistance to oils, solvents, and water, nitrile O-rings are commonly used in quick couplings, fuel tanks, engines, and other automotive applications.

Learn more: What is a quick-connect coupling and how does it work?

Silicone O-rings

Silicone O-rings retain their flexibility and can operate at temperatures between -58°F and 450°F (-50°C and 232°C). Some of these O-rings can withstand even more extreme temperatures (-100°C to 310°C), making them excellent for a wide array of applications. Silicon O-rings are also resistant to ozone and UV radiation, making them excel in outdoor applications.  Because of their great temperature resistance, these O-rings are most often used in dry heat applications. The most common fields where silicone O-rings are used are electronics, medical, aerospace, food and beverage, and pharmaceutical. In the water treatment world, silicone O-rings can commonly be found in UV disinfection systems.

Learn more: What is a UV disinfection system?

Viton™ O-rings

Viton™ is a brand of rubber and synthetic fluoropolymer used not only in O-rings, but also in cables, hoses, and tubes. Viton™ O-rings are designed for use in high temperature applications in systems where oils, fuels, aromatics, solvents, or hydraulic fluids are present. These O-rings boast an optimal temperature range of -15°F to 450°F (-26°C to 232°C). Their resistance to these temperatures and liquids makes Viton™ O-rings ideal for aircraft, automotive applications, agricultural pumps, and pest control. They can also be found in filter housings in water treatment systems.

EPDM O-rings

EPDM, also known as ethylene propylene, is a synthetic rubber made of ethylene, propylene, and a diene monomer. This third monomer allows it to be flexible, durable, and useful for many applications. EPDM has an operational temperature range of -60°F to 250°F (sulfur cured) or 300°F (peroxide cured) (-50°C to 120°C or 150°C). These O-rings feature excellent electrical insulation, good compression set, and good wear resistance. Because of these characteristics, EPDM O-rings are commonly used in automobile systems, hot water applications, fittings, and water treatment systems.

O-rings in water treatment systems

O-rings are essential components to practically all water treatment devices and systems. Without a proper seal, these systems would leak, preventing water from travelling from point A to point B and damaging sensitive components in the process. If you are looking for an O-ring for your water treatment system, explore our O-ring collection featuring seals for filter housings, UV systems, pumps, and other water applications.

Tips for replacing an O-ring in a water treatment system

Replacing an O-ring is as simple as opening your treatment system, removing the old O-ring, and replacing it with the new one. When replacing a seal in a water treatment system or pump, ensure there is no power flowing to the system and all water supplies have been shut off. While replacing an O-ring is a simple task, installing the new seal incorrectly can cause leaks and potentially damage your treatment system. Even though O-rings come in all shapes and sizes, changing them is an easy process in most cases. The only tools you may need are a flathead screwdriver or other sharp metallic tool to pry off the old O-ring and whatever tools you need to access the inside of your system, such as a filter housing wrench. The new O-ring is dropped into a groove that provides feedback as to whether the O-ring is fully seated or not. You may need to lubricate your O-ring slightly to ensure a proper installation. Before lubricating an O-ring, ensure that the lubricant and O-ring material are not incompatible, such as Vaseline and rubber. Do not attempt to run your system if you are not certain that the new O-ring is installed correctly.


If you have any additional questions, please do not hesitate to contact us.

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