It’s no surprise that rubber seals are among the most popular choices when it comes to ensuring an airtight and watertight fit in a wide variety of industries and applications. From aerospace to the automotive industry, from electronics to engineering, from medicine to mining; regardless of the sector, rubber seals are consistently preferred as a means of creating an impervious connection.
Why is this so? There are many reasons that rubber seals are a good fit (excuse the pun) for a range of situations and circumstances. Here are just a handful of the many benefits that rubber offers over other alternative materials when it comes to creating a gasket or O-ring between two component parts of equipment, machinery or other working apparatus:
- Even at very low temperatures, rubber (especially silicone rubber) retains a high degree of flexibility, meaning it will absorb any pressure placed upon it and mould itself to the contours of the groove (or gland) into which it is placed.
- Temperature resistance. Rubber is capable of withstanding extreme temperatures at both ends of the scale. In particular, silicone rubber can tolerate lows of up to -100°C and highs up to 310°C This makes rubber seals ideal in environments prone to massive swings in temperature.
- Rubber is an incredibly durable material which will absorb pressure applied on it and create an impervious seal that is increases in strength in direct proportion to the forces exerted upon it. It will also maintain this integrity for significant spells and although there are breaking points for both the amount of pressure it can withstand and the length of time that it can do so, its credentials are very impressive in both respects.
- Rubber is a highly malleable substance and can easily be moulded into all kinds of shapes and sizes, making it ideal for use in a variety of different applications and industries. Whether it’s a standard O-ring seal that’s needed or a more bespoke solution, rubber has the versatility to satisfy any situation.
- Depending on the type of rubber, many rubbers are non-toxic materials which won’t corrupt or compromise any substance with which it comes into contact or any environment into which it is placed. Thanks to the fact that it does not impart odours or flavours to surrounding mechanisms, it’s a highly popular choice for the food, pharmaceutical and medical industries.
- Silicone rubber is compatible with a wide range of different sterilisation techniques, including dry heat, electron beams, ethylene oxide, gamma radiation and steam autoclaving. This, coupled with the non-toxic properties mentioned above, allows us to offer medical grade materials.
- Compatibility with other materials. Rubber can easily be mixed with other substances to enhance certain aspects of the seal in question, including its tolerance to extreme temperatures, its compression capabilities and the length of its life.
Choosing the rubber seal that’s right for you
As you can see, there are any number of reasons why rubber seals offer a quality and comprehensive solution to sealing problems in a number of different industries. If you’d like to take advantage of the incredible properties of this versatile material, why not browse our range of rubber seals and gaskets suitable for all kinds of circumstances.
Alternatively, if you’d prefer to hear some advice on which type of seal would best benefit your unique situation, we’re on hand to dispense any guidance and answer any questions we can. Simply get in touch via our online form, give us a call on +44 1909 560 203 or drop us an email at firstname.lastname@example.org and we’ll take things from there. We look forward to hearing from you soon
O-rings are an essential component in machinery across all kinds of industries and have been for well over a century. Despite their importance, the basic design of an O-ring has changed very little over the last 100 years – but the materials used to make them have undergone significant advances. Today, one of the most popular substances used in the manufacture of O-rings is silicone.
Silicone is the name applied to any synthetic compound in which siloxane is a repeating constituent part. When it comes to silicone O-rings, they are impervious to extremes of temperature. The same type of silicone rubber that is used to manufacture O-rings is also employed in a variety of other household items, from kitchen utensils to electronics and insulation to medical devices.
Strengths and weaknesses of silicone O-rings
Perhaps the biggest defining characteristic of silicone O-rings is their resistance to extreme temperatures. Capable of withstanding lows of -100°C and highs of up to 310°C, silicone O-rings can even tolerate even greater extremes for short periods of time.
As well as dealing with extremes, silicone O-rings are also extremely flexible, even in low ambient temperatures. They boast a low compression set as well, making them the perfect choice for compression force sealing and working among high temperatures and pressures. As well as being resistant to heat and cold, silicone O-rings boast tremendous resilience when exposed to ozone, acid, chemicals and oils. What’s more, the colour of the material used does not have any bearing on its effectiveness or capabilities, affording user greater aesthetic control when selecting the design of the O-ring. Silicone can be matched to any RAL or Pantone number.
On the other hand, their tensile strength is not as accomplished as certain other materials and they are prone to suffering damage from tears and abrasions. This makes them more suited to static applications than dynamic ones, since a moving part is more likely to rupture their surface. Similarly, they are not the best choice in situations exposed to naked flames and they do not offer as robust impermeability as some other O-ring materials.
Applications of Silicone O-rings
Thanks to their supreme resistance to extremes of temperature, their unparalleled flexibility and their ability to withstand exposure to all kinds of substances and gases, silicone O-rings are suitable for a wide range of applications in many different industries.
These applications include (but are not limited to) automotive manufacturing, aerospace, electronics, cooling systems, pressure cleaners and water processing equipment. Furthermore, the fact that they do not impart any discernible odour or taste to their immediate surroundings or the substances with which they come into contact makes silicone an ideal choice for O-rings in applications dealing with food production and processing, medical and pharmaceutical purposes and semiconductor systems.
In terms of specific environments, silicone O-rings are particularly useful in environments which experience dry heat, ozone exposure or contact with mineral oils with minimal additives. On the other hand, they do not perform so well in situations where they may encounter concentrated acids, ketones (such as acetone or methyl ethyl ketone [MEK]), fuels, gear lubricants or steam.
Advice from the experts
If you’re still unsure whether a silicone O-ring is the best solution to your particular conundrum, it’s always preferable to seek professional help rather than hazarding a guess and hoping for the best. Our dedicated team of experienced O-ring experts are on hand to answer any questions and offer any advice you might need – simply complete our online form, give us a call on +44 1909 560 203 or drop us an email at email@example.com and we’ll get back to you as soon as we can.
O-rings are a tried and trusted method of sealing two component parts in a wide range of industries that have been relied upon for well over a century. However, just because they are an excellent solution to a universal challenge, that doesn’t mean that they aren’t susceptible to failure on occasion.
There are many different reasons why an O-ring might become damaged and the seal it is protecting become compromised. Here is a quick rundown of the five most common contributing factors to an O-ring failure, as well as advice on how to determine which problem is responsible and how to rectify it.
- Symptoms: O-rings which suffer from abrasion might have a rough or disfigured surface, while in extreme cases there may be ruptures or lacerations in the outer ring.
- Cause: One of the most common forms of O-ring failure, abrasion is caused by too much contact between the O-ring surface and the surrounding architecture. This can happen when not enough lubricant is used or when alien substances infiltrate the gland.
- Solution: Correct use of appropriate lubricant normally solves the problem, while the use of scraper rings may be necessary to prevent contaminants from entering the gland.
- Symptoms: Blisters, discolouration, lacerations and swelling can all be indicative that the O-ring has become exposed to chemicals with which it is not compatible.
- Cause: Exposure to certain chemicals can result in reactions with some type of elastomers. Depending on the O-ring material and the chemical in question, this can lead to reduced flexibility, strength and cross-link density, while swelling often incurs extrusion and seal failure.
- Solution: It’s essential that the right type of O-ring material is used for the right application. Many substances boast high resistance to chemicals; be sure to choose one of these if exposure is a concern.
- Symptoms: Once removed from the gland, an O-ring should return to its original O-ring shape. However, those which have taken on a “set” will retain characteristics of the gland even after use, including flattened surfaces instead of circular ones.
- Cause: O-rings can lose their resilience and ability to return to their original form after exposure to extreme temperatures, through prolonged use or being fitted in incorrect groove geometry.
- Solution: Selecting an O-ring material with a low compression set or a high tolerance to extreme temperatures should ensure that the O-ring has a longer life. Ensuring the correct amount of pressure is being exerted on the O-ring, by using correct groove dimensions, is also key to avoiding compression set.
- Symptoms: The surface edges of the O-ring have a chipped or frilly appearance and it may seem to be peeling away from the material underneath.
- Cause: Prolonged exposure to high amounts of pressure or repeated bursts of intense pressure can force an O-ring into the clearance gap between the two mating surfaces. In dynamic applications, the movement can then erode the O-ring’s surface, resulting in extrusion and nibbling.
- Solution: Using the correct size of O-ring is the most important precaution when avoiding extrusion and nibbling, but minimising the appearance and size of clearance gaps and selecting a hardier material for the O-ring can also help.
- Symptoms: Two types of thermal damage can afflict O-rings: degradation and extrusion. The former will exhibit cracks and fissures on the O-ring’s surface, as well as a shinier aspect on occasion. The latter will result in the same symptoms outlined for extrusion and nibbling above.
- Cause: Both thermal degradation and thermal extrusion are caused by elevated temperatures. The former comes about when the temperature exceeds the O-ring elastomer’s upper threshold, while the latter occurs when the O-ring’s tolerance level is higher than the surrounding materials.
- Solution: The gland should be designed to withstand the same temperatures as the O-ring, while selecting the right material for the O-ring itself is also key to circumventing this problem.
The the most common seal used in a multitude of industries is O-rings. From aerospace to chemical processing, food and pharmaceutical industries, O-rings come in a variety of robust materials that offer high-quality and reliable seals for many different fields. Whether it’s heavy plant or agricultural machinery, these donut-shaped rings are suitable for the most demanding of jobs.
As O-rings are used regularly in a number of applications, sometimes you may not even realise they are there until one starts to crack and then leak. One of the reasons this can happen is due to ozone exposure. In manufacturing this can cause aggravation, but out in the field ozone damage can be detrimental and if left unchecked, it can lead to serious injury or even death. This is why it’s important to know how ozone damage can occur and what you can do to prevent it.
Why ozone causes O-ring cracks
O-ring failure can be attributed to a combination of causes, but it’s mainly exposure to oxygen atoms that causes cracks in rubber O-rings. Exposure to oxygen is inevitable as it’s in the air we breathe, but typically oxygen atoms join up in pairs to form dioxygen which is the majority of the oxygen in the atmosphere. Occasionally, oxygen atoms will join in groups of three and this creates the ozone substance.
In the stratosphere, ozone is extremely useful and protects us from the sun’s harmful rays. However, up-close it can cause health problems and even in tiny concentrations it can cause cracking in rubber O-rings. Ozone concentration in the stratosphere is somewhere between two and eight parts per million but in the troposphere concentrations are above 75 parts (per billion).
Most rubbers are polymers which consist of individual units that are bonded together in a long chain. If the polymer chain develops a weak spot because of exposure to ozone, the O-rings can crack and and over time will get bigger until the damage can be seen by the naked eye.
Preventing ozone damage to O-rings
As expert manufacturers and distributors in the UK, NES are a great resource when it comes to knowing how to ensure O-rings have a long life. In industry applications, the main drivers of ozone exposure are electrical arcing, ultraviolet light and electromagnetic fields (the main reason for higher ozone levels in the upper layer). In order to prevent ozone damage, it’s vital to store and install O-rings correctly.
Firstly, inspect your storage area for any ozone-generating equipment that could cause damage to the O-rings. Ensure O-rings are not stored within range of an electric motor, or other potential sources of electrical arcs. O-rings should be stored in a dark room, away from florescent bulbs and direct sunlight. These forms of ultraviolet light can cause damage to the rubber and lead them to crack before they’ve even been used. Try not to store O-rings in a stretched state – ozone damage will typically only occur to stretched O-rings. If you have to store O-rings in a stretched state, keep them in an airtight bag until ready to use.
It’s recommended to install O-rings into the mating part within 24 hours of installing the O-ring fitting. When installing, wet the O-rings with a grease to protect from them from ozone. In applications where long-term exposure is likely, use O-rings made from ozone-resistant materials such as EPDM or fluorocarbon. EPDM O-rings are used for sealing in many industries because of the material’s excellent resistance to ozone and UV as well as heat, steam, mild acidic and oxygenated solvents.
Northern Engineering (Sheffield) Ltd are a leading O-ring suppliers and manufacturers who distribute a range of engineered, elastomeric products across the globe. From food and beverage industry to the pharmaceutical industry we are reputable O-ring suppliers for a variety of businesses across all industry sectors.
NES offers an extensive range of O-rings that can be used for both domestic and more demanding applications. We supply O-rings that are developed to withstand extreme temperatures, are oil and ozone resistant, and even those that can be used for bio-technology and hygiene equipment.
Our vulcanised O-rings are used in many markets across diverse applications due to profile and material versatility. Manufactured in materials such as Silicone, Nitrile, EPDM and Viton™, they are developed to best suit your individual application. We also offer a range of FEP and PFA encapsulated o-rings to suit your applications requirements
For more technical information and to learn more about the O-rings we manufacture and the industries we supply to, you can explore our full product range on our website. Need a sealing solution for your project? Get in touch with us and we’ll tell you more about how we can provide you with O-rings to best suit your needs.
Different types of O-ring applications
One of the most crucial components of modern industry, the humble O-ring is as versatile as it is reliable. Despite having been first patented in 1896 by Swedish inventor J O Lundberg, the basic design of the O-ring has changed very little in the intervening century. Neither has the function it performs or the valuable service it provides, facilitating an airtight or watertight seal in any number of different applications and industries.
Of course, the materials used to construct O-rings have been developed and improved over the years, meaning that there are now a wide variety of elastomers used in O-ring manufacturing to meet the needs of a range of applications. From O-rings resistant to extreme temperatures to those impervious to chemical damage, there’s sure to be an O-ring to suit your specific situation. However, it’s imperative that before making a purchase, you consider which material would be satisfy your circumstances, since using an O-ring that is too large, too small or made of the wrong material could lead to its failure and potentially jeopardise the equipment it services.
In order to make an educated decision on which O-ring is right for you, this handy guide intends to provide some background on how O-rings work, how they’re made and how they lend themselves to a variety of different applications.
How does an O-ring work?
As the name suggests, O-rings are circular, donut-shaped mountings which are compressed between two different components to form a better, tighter seal. In essence, they are very similar to a standard form of gasket, with the difference being that O-rings are specifically designed for industrial use in applications where they will be subjected to extreme temperatures, pressures or substances. In these cases, a standard gasket made of rubber, cork or metal would not withstand the tension exerted upon it, which is why O-rings are such a simple but effective solution to an age-old problem spanning many industries.
By contrast, O-rings are constructed of more durable elastomers which are capable of withstanding the extreme conditions to which they are subjected. They work by being placed in the channel or groove (known in industrial terms as a gland) between two different parts of machinery, which can be either static or dynamic. When the two components are compressed together, the O-ring is designed so that its shape will mould to fit the unique dimensions of the surfaces pressing against it, thus creating an impermeable seal which won’t allow either water or air to enter. The greater the amount of pressure exerted on the O-ring, the tighter the seal it will create – up to a point. However, it’s essential to ensure that not too much pressure is applied to the O-ring or it will become damaged and the seal itself will become compromised.
Another attractive selling point of O-rings is that once the two compressed parts of the machinery are detached and the pressure being exerted on the O-ring is relaxed, it will return to its original donut shape. While this does mean that O-rings can be reused for several different purposes, it should be remembered that it cannot be recycled indefinitely. Eventually, the pressures exerted upon it will negatively impact the consistency and resiliency of the O-ring and it must be replaced with a fresh one if an adequate seal is to be maintained.
How is an O-ring made?
Due to the fact that the design of O-rings has remained largely unchanged since their inception over a hundred years ago, the manufacturing process also remains relatively simple. The rings can be created through the use of a number of different techniques, including compression moulding, injection moulding, transfer moulding or vulcanisation. Nowadays, modern advances in scientific and technology understanding mean that O-rings can be constructed from a wide variety of materials, including nitrile, silicone and fluorocarbons (among many others). The type of material used will be dependent on the specific purpose and circumstances of the O-ring in question.
Different types of O-ring applications
Whether it’s for use in an industrial power plant, as part of heavy-duty agricultural machinery, underwater in a marine environment or amongst the cogs and pistons of the automotive industry, there’s sure to be an O-ring that’s perfect for every purpose. But with so many materials available to choose from, it can be difficult to know which one is right for you.
Here’s a breakdown of the various kinds of O-ring available, as well as the advantages of each and the possible applications to which they may be suited.
Widely regarded as a general-purpose type of O-ring, Nitrile elastomers (also known as Buna-N or NBR) offer a respectable temperature range of between -50°C and 120°C, with excellent resistance to tears and abrasive treatment. Nitrile also enjoys decent resistance to water, oils and some hydraulic liquids, although it is susceptible to damage from automotive brake fluid, halogenated hydrocarbons, ketones, nitro hydrocarbons or phosphate ester. As such, it’s suitable for use in select purposes in agriculture, the automotive industry, dairy, mining, plumbing and railways.
With one of the widest temperature ranges of any O-ring material, silicone O-rings can withstand temperatures of between -100°C and 300°C. Indeed, this hardy material has even be known to tolerate greater extremes (-115°C to 315°C) for a limited time, making it an ideal choice for applications where very high or low temperatures are a factor. It offers great flexibility and performs brilliantly alongside water, steam or petroleum, but is prone to damage from abrasion and tearing. As a result, it’s better suited to static applications rather than dynamic ones.
Also known as FKM O-rings, Viton™ O-rings are made from fluorocarbons and boast resistance to temperatures from -40°C up to 250°C, low gas permeability, superb mechanical characteristics and a low compression set. They are highly suitable for use with acids, halogenated hydrocarbons, petroleum and silicone fluids or gases. However, they should not be used in conjunction with amines, esters, ethers with a low molecular weight, hot hydrofluoric acids or Skydrol. Their incredible versatility makes them popular in a wide range of industries, including the automotive sector, aviation, chemical processing and mechanical engineering plants.
FEP O-rings pair a silicone or fluorocarbon core with a coating of fluorinated ethylene propylene (FEP), which offers users several distinct advantages over a standard PTFE O-ring. Firstly, they are capable of handling temperatures of between -60°C and 260°C for silicone cores and -20°C and 204°C for fluorocarbon cores. Secondly, they also provide superb elasticity and low friction levels in comparison to their PTFE counterparts. Although they are best suited to static applications, they can also be adaptable to dynamic ones where the movement is slow and short. This makes them popular in the chemical, food, petrochemical and pharmaceutical industries.
O-rings which are encapsulated with perfluoroalkoxy (PFA) are an attractive alternative to PTFE or FEP O-rings which offer several advantages over their competitors. In comparison to PTFE, PFA O-rings are a more cost-effective option, while the substance has greater resistance when dealing with temperatures of above 250°C than FEP does. Similarly, it is also better equipped to keep a variety of chemicals from permeating its seal, making it ideal for use within the chemical and petrochemical industries, the food sector and with pharmaceutical organisations.
In this context, USP stands for United States Pharmacopeia and the rubber compounds which have achieved a Class VI certification definitely offer a unique selling point, too. All of the elastomers which receive this accreditation are subjected to rigorous testing procedures, which assess their consistency, purity, quality and strength to ensure they are safe for use in situations where human life is at stake. As such, USP Class VI O-rings are in high demand among the medical and pharmaceutical industries.
While all of the O-rings listed above are created through moulding techniques, Vulcanised O-rings (or Vulc O-rings) are made by treating the parent material with sulphur at very high temperatures and splicing its ends together to create the donut shape. This allows for a much faster creation of the production on a more cost-effective scale, with an average of 90% of the joint strength of the equivalent moulded part. As such, Vulc O-rings are an attractive alternative whose versatility and low compression values make them suitable for a range of industries where the end user wants to avoid the higher tooling costs of moulded O-rings.
As well as the economic advantages of vulcanisation opposed to moulding, the unique method of manufacturing O-rings means that there is no limit on the size to which they can be created. Standard larger O-rings range up to 25.4mm in size, though it is a fairly simple process to manufacture a bespoke O-ring to any specifications required. As with standard Vulc O-rings, dispensing with the need for moulds and expensive tooling equipment not only slashes the cost incurred, but also greatly reduces lead times, making them ideal for applications of all kinds.
Expert advice from the professionals
Still unsure as to which type of O-ring would suit your situation best? Not to worry. Our extensive range of O-rings is guaranteed to have a product that will satisfy your unique circumstances and our friendly team is on hand to provide any guidance you might need in making your choice. Simply fill out our online form, give us a call on +44 1909 560 203 or drop us an email at firstname.lastname@example.org and we’ll be happy to help. We’re waiting to hear from you.
New technology is always being made available, but some innovations seem to stand the test of time. One such product is the O-ring, a simple gadget that has so many applications and has been widely used since it’s conception in 1896. If you’re wondering how do O-rings work, let’s take a delve into the basics of this handy mechanical piece to see what the secrets of its success really are.
What are O-rings?
An O-ring is one of the simplest types of seal available, and despite its basic design, it’s applications and usefulness are unrivalled. Used to prevent leakages, these simple seals can be used in anything from cylinders to pumps, connectors to vacuum seals. They can be manufactured from synthetic rubbers such as nitrile rubber or PTFE, from thermoplastics such as TPU or TPE styrenics, or from specialist materials for chemical compatibility.
The O-ring itself is pretty self-explanatory; it’s essentially a ‘O’ shaped ring of material which is used as a gasket. It is designed to sit within a groove and to be compressed during assembly between the component parts which then, thanks to the dynamics of the shape of the O-ring, creates a perfect seal.
How do O-rings work to create a seal?
In any type of machinery, you’ll undoubtedly find an O-ring or two. They are inexpensive, reliable and easy to use, which makes them infinitely popular in the design of both static and dynamic processes. The can stand thousands of PSI of pressure, but how do O-rings work to do this?
The mechanics of an O-ring are relatively simple; here’s how they work:
- The O-ring is manufactured alongside (usually) metallic hardware to fit perfectly within the glad of the assembly.
- During assembly, the O-ring is fitted within the glad and is compressed as the second piece of hardware is fitted into place.
- This compression diametrically squeezes the seal, resulting in a force which ensures full contact with both the inner and outer walls of the gland.
- With no pressure, the natural resilience of the O-ring material will create a perfect seal and stop fluid from passing the barrier. When fluid begins to put pressure on the O-ring, the ring is pushed against the wall of the gland on the low-pressure side, therefore increasing the strength of the seal.
- When pressure is released, the properties of the O-ring material allow it to return to its original shape, maintaining the seal and the integrity of the O-ring.
The mechanics of how O-rings work might sound complicated when explained like this, but the result is simple to understand; no leaks. The simplicity of the O-ring is what has contributed to the longevity and popularity of this product.
What would stop an O-ring from working?
When used correctly, O-rings can provide an effective seal and will function perfectly for many years. However, it’s crucial that the correct O-ring is selected for each application. There are a wide variety of elastomers and materials which can be chosen from and selecting the correct hardness and material type is essential for effective functionality. Other factors which can affect the effectiveness of the O-ring include whether the machinery is static or dynamic, how much pressure will be exerted and whether there are occasional pressure spikes in the system.
So, now if someone asks you ‘how do O-rings work’, you’ll be happy to tell them the answer. For more information on O-rings or for advice on the right products for your applications, get in touch with our technical team and they’ll be happy to help
In a world full of acronyms, trade names and technical jargon, it can be hard to know what’s what sometimes. If you’re wondering what the difference is between PTFE and Teflon, and who would win between Teflon vs PTFE, let’s explore these materials and see what makes them unique.
What is PTFE?
Let’s begin our exploration of Teflon vs PTFE with a closer inspection of what PTFE actually is. To give it it’s full title, polytetrafluoroethylene is a synthetic polymer consisting of two simple elements; carbon and fluorine. It is derived from tetrafluoroethylene (TFE) and has some unique properties that make it a useful material in a wide range of applications. For example:
- Very high melting point: With a melting point of around 327°C, there are very few situations where PTFE would be damaged by heat.
- Hydrophobic: It’s resistance to water means it never gets wet, making it useful in cooking, wound dressings and more.
- Chemically inert: The majority of solvents and chemicals will not damage PTFE.
- Low coefficient of friction: The coefficient of friction of PTFE is one of the lowest of any solid in existence, meaning nothing will stick to it.
- High flexural strength: It’s ability to bend and flex, even at low temperatures, means it can be easily applied to a variety of surfaces without losing its integrity.
All these unique properties mean PTFE is a very useful material and is widely used in both domestic and commercial applications. You probably have PTFE in your own home, coating your non-stick cookware or providing stain resistance in your carpets and fabrics. You may also find it in nail polish, wiper blades and hair styling tools.
In other situations, PTFE is a useful product for coating the inside of pipes carrying corrosive chemicals or very hot materials. It has been successfully used in the manufacture of artificial body parts thanks to its inert nature which makes it unlikely to be rejected by the body. It can be used in lubricants and was even used in the Atomic Bomb to seal the gaskets holding the uranium.
What is Teflon?
It’s clear that PTFE is a very useful, unique product, but in order to establish the winner between Teflon vs PTFE, we need also to consider what Teflon is too. Discovered in 1938, Teflon was developed by the DuPont Co and managed by a spin-off of the company known as Chemours. Chemours trademarked the name Teflon in 1945 and began selling products treated with this non-stick, heat resistant material in 1946.
Teflon was actually discovered by accident, by a scientist called Dr. Roy Plunkett. He was working for DuPont in New Jersey trying to develop a new refrigerant, when he noticed that the TFE gas had flowed out of the bottle he was using, but the bottle was not weighing empty. Curious as to what was causing the weight, he investigated the interior of the bottle and found it was coated with a waxy material, slippery and oddly strong, which we now know to be Teflon.
Teflon is a synthetic polymer containing carbon and fluorine called polytetrafluoroethylene. That’s right, Teflon is PTFE but by another name. Teflon is the trademarked brand name for PTFE owned by Chemours, and just as we call our vacuums Hoovers and sticky tape Sellotape, so we’ve come to know PTFE by the name it was given.
Which is better in Teflon vs PTFE?
If you’ve been paying attention so far, you’ll already know what we’re going to say here. There is no winner, no better product and no reason to compare the two substances any further. In conclusion, if you’re wondering about Teflon vs PTFE, wonder no more, because they are, in fact, one and the same thing, different only in name and nothing else.
O-rings are one of the most widely used, reliable and inexpensive components of precision machinery, but they are not completely infallible. Certain issues can lead to O-ring failure, and when this happens, it’s crucial to identify the cause behind the fail so that it doesn’t happen again. Here’s what you need to know about O-ring failure, and the typical reasons why.
Typical causes of O-ring failure
Experience shows us that the most common reasons for O-ring failure include:
- Improper gland design: When the gland allows too much or two little compression, the O-ring can fail.
- Incorrect O-ring size: An improperly sized O-ring can fail under pressure.
- Incorrect O-ring material: Hardness and type of material must be correctly selected to ensure failures don’t occur.
- Improper installation: O-rings must be correctly sited to ensure they can function effectively.
- Improper lubrication: An O-ring requires adequate lubrication to allow it to flex freely under pressure.
- Contamination: Chemicals and other environmental elements that come into contact with the O-ring can cause degradation and failure.
If you’ve experienced O-ring failure, you’ll need to narrow down the cause to prevent another issue further down the line. Sometimes inspecting the failed O-ring can give clues as to why the failure occurred. Let’s take a look at some of the most commonly encountered problems and how you can diagnose the fault.
Abrasion occurs when there is repeated contact between the O-ring and the materials it is housed within. Without proper lubrication, this contact can start to wear away the O-ring, eventually causing failure. You can check for this by inspecting the O-ring and noticing a grazed surface. In more damaged components, there may be deep lacerations and even breaks.
The fix: Use the correct O-ring sealing material when assembling the system and ensure that the metal surface of the housing is correctly finished.
This issue means that the O-ring has lost its elasticity and is unable to return to its original O shape. It can be caused when working with elevated temperatures and is a particular risk when the gland design is faulty. You’ll notice that the O-ring has become flattened and is less circular in shape.
The fix: If you’re working with extreme temperatures, using elastomer materials with higher temperature capabilities or low compression set ratings will extend the life of your O-ring.
Nibbling and extrusion
Under extremes of high pressure, the O-ring can be forced into the gaps in the housing, causing what is known as extrusion. You’ll see evidence of this if the ring has a frilly appearance on the low-pressure side. Cycles of pressure and no pressure can cause the ring to become damaged on this extruded edge, a condition we call nibbling which is evident by chipping and peeling of the O-ring’s edge.
The fix: Using a harder seal can help, as can using secondary O-rings to reduce gaps in the assembly.
O-ring failure can occur if the operating temperature is higher than the temperature limit of the material in use. Two types of damage can occur in this situation. The first is known as thermal degradation, where the temperature has reached such a level that it has interfered with the chemical composition of the O-ring, making it harder and less elastic. You’ll see evidence of this if the surface of your failed O-ring is cracked or shiny. Thermal extrusion occurs when the O-ring extrudes into the gaps on both sides due to temperature elevation. Unlike the extrusion discussed above, this will often occur on both sides of the ring.
The fix: Choosing the right material for your O-ring is essential, so if you know you’ll be working at high temperatures, take advice on which materials will cope. Designing the gland so there is sufficient space to accommodate the expanded O-ring can avoid extrusion too.
There are numerous other reasons for O-ring failure, so if you’ve encountered a problem and cannot diagnose it from our guide, get in touch with our experts and we’ll be happy to help. When used correctly, O-rings are amazingly robust pieces of kit, so take professional advice and ensure you’re getting the right tool for the job.