Below is a summary of the different commonly used o-ring materials and types.
Because of the range of materials available, determining which o-ring is appropriate for use in a specific application is a process whose importance cannot be overstated. The information below, along with consultation with the resources offered by o-ring manufacturers and suppliers can assist designers and engineers with narrowing the options and making an informed decision for their project. The materials covered below include:
1. Nitrile (Buna-N)
2. Ethylene Propylene Rubber(EPR)
9. Ethylene Propylene(EPDM)
· Temperature range: The nitrile O-ring temperature range is between -65 degrees Fahrenheit and 300 degrees Fahrenheit.
· Suited for: General purpose seals, such as petroleum oils, water, and some hydraulic fluids. Buna-N is also resistant to tears and abrasive treatment.
· Avoid: Buna-N can have problems with automotive brake fluid, ketones, phosphate ester hydraulic fluids, and nitro and halogenated hydrocarbons. While it is ozone and weather-resistant, this resistance is not infallible but can be supported through compounding.
· Applications: Nitrile functions well in applications that have limited temperature and resistance requirements.
· Temperature range: Between -65 degrees Fahrenheit and 300 degrees Fahrenheit.
· Suited for: Skydrol, a hydraulic fluid, has a noxious smell and can irritate the skin, and its corrosive properties can be damaging to equipment. EPR o-rings work well with Skydrol and other hydraulic fluids, as well as steam, water, silicone oils, brake fluids, and alcohol.
· Avoid: Similar to nitrile, EPR is not perfect for a wide range of applications due to wear and tear issues.
· Applications: The aerospace industry uses EPR o-rings in hydraulic pumps.
· Suited for: Fluorocarbon is an all-around material that can handle a number of applications, especially diverse sealing jobs that involve movement. It is also suited for petroleum oils, silicone fluids and gases, acids, and some halogenated hydrocarbons, like carbon tetrachloride.
· Avoid: Fluorocarbon is not recommended for Skydrol, amines, esters, and ethers with low molecular weight and hot hydrofluoric acids.
· Applications: Fluorocarbon o-rings are very versatile, and features in many different automotive, appliance, and chemical processing industries.
· Temperature range: The neoprene O-ring temperature range is between -65 degrees Fahrenheit and 300 degrees Fahrenheit. Types of O-ring seals.
· Suited for: Neoprene can seal refrigerants in refrigeration and air conditioner units, as well as petroleum oils and mild acid resistance silicate ester lubricants.
· Avoid: Finished neoprene products are often compounded with lead-based agents, which can be hazardous to human health. Additionally, some people are allergic to basic neoprene. In a functional sense, it is not very resistant to petroleum lubricants and oxygen.
· Applications: Neoprene functions well in refrigeration units of air conditioning systems.
· Temperature range: Between -65 degrees Fahrenheit and 212 degrees Fahrenheit.
· Suited for: Polyurethane features abrasion and extrusion resistance, as well as general toughness.
· Avoid: Applications requiring good compression and heat resistance would not be suitable for polyurethane.
· Applications: Polyurethane o-rings are often used for hydraulic fittings, cylinders and valves, pneumatic tools, and firearms.
· Temperature range: Between -120 degrees Fahrenheit and 450 degrees Fahrenheit, although silicone o-rings have been shown to withstand -175 degrees Fahrenheit during short periods of exposure.
· Avoid: Silicone exhibit Spoor tear resistance, abrasion, and tensile strength. The poor abrasion resistance means they are better suited for static applications than dynamic. They do perform well with water, steam or petroleum fluids, either.
· Applications: High-temperature fuel injection ports can use silicone 0-rings.
· Temperature range: Between -100 degrees Fahrenheit and 500 degrees Fahrenheit.
· Suited for: Pure PTFE o-rings are very rigid and hard to apply, but PTFE encapsulated o-rings handle surface wear well, in addition to exhibiting corrosion and abrasion resistance, non-permeability, chemical inertness, and low absorption.
· Avoid: Like silicone, PTFE is rigid and is better suited to static applications.
· Applications: Examples of PTFE o-ring uses include automotive steering devices and paint guns.
· Temperature range: Between 5 degrees Fahrenheit to 625 degrees Fahrenheit.
· Suited for: Applications, where there is a high cost of maintenance or downtime, where high-temperature resistance is needed, where high chemical resistance is needed, or low outgassing is a requirement.
· Avoid: Not suitable for use with molten metals, gaseous alkali metals, or halogenated freons/fluids.
· Applications: Oil & Gas, Life Science and Medical applications, Food & Beverage manufacturing
· Temperature range: Between -65 degrees Fahrenheit to 300 degrees Fahrenheit.
· Suited for: Applications with exposure to sunlight, ozone, weathering, hot water, stream, automotive and aircraft brake fluids, some acids and bases, ketones, alcohols, plumbing applications.
· Avoid: EPDM is not suitable for use with petroleum oils, fuels.
· Applications: Life Science Industry, Pharmaceutical & Medical applications, Food & Beverage manufacturing, Drinking water applications.
· Temperature range: Between -90 degrees Fahrenheit to 350 degrees Fahrenheit.
· Suited for: Applications with exposure to jet fuel, dry heat, some petroleum-based solvents, chlorinated solvents.
· Avoid: Ketones such as MEK, Phosphate esters, some acids, automotive and aircraft brake fluids, ammonia
· Applications: Aerospace, Automotive, and Chemical Industries.
This article reviewed the different types and material options available for o-rings as well as the considerations for their selection. For information on other topics, consult our additional guides or visit the Thomas Supplier Thomas Supplier Discovery Platform where you can locate potential sources of supply for over 70,000 different product and service categories, including over 1,200 suppliers of o-rings.