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...
- This compression diametrically squeezes the seal, resulting in a...
How do O-ring seals work?
In very basic terms, o-ring seals work by sitting in a groove or channel between two surfaces/components that are going to be mated or pushed together. The o-ring, generally made of some form of elastomer, sits in the join between these two parts, and becomes compressed in order to help form a tight seal.
How does O-ring stretch affect seal compression?
The force required to compress an o-ring is a result of the durometer and cross-section diameter. O-Ring stretch affects the seal compression by reducing the cross-section, which reduces the sealing potential of the o-ring. At zero or very low pressure, the natural resiliency of the rubber compound provides the seal.
What makes an O ring a good sealer?
The design of the O Ring’s groove is fairly straightforward. A dependable and economical seal is acquired by following well-developed principles for groove geometry. The primary reason an O Ring makes a remarkable seal is its proneness to return to its original shape when the cross-section is compressed.
What are the different types of O-ring seals?
In addition to the standard torus-shaped o-rings that are familiar worldwide, they’re also produced in other shapes (square-cut, x-shaped, quad rings, etc) for more specific applications as and when required. What are O-ring seals used for?
What do O-ring seals do?
O-rings seal by mechanical deformation that creates a barrier to a fluid's potential leak path between two closely mated surfaces. O-rings are typically installed in a groove that's machined or molded in one of the surfaces to be sealed.
What makes an O-ring a good seal?
The ring is compressed radially in its groove, with a compression of the cross-section of from 2% to 6%, according to thickness. This ensures good sealing with comparatively long life even with inadequate lubrication.
Are O-rings and seals the same thing?
An O ring is a seal in a circular ring shape. It can be made with a variety of materials, and it is most commonly made by either moulding or extrusion. Generally, this seal has some give and can withstand pressure and vibration.
How do you install an O-ring seal?
Tips for O-Ring InstallationLubricate the threads. As the shaft consists of threading, it's easy for the rubber seal to tear during installation. ... Cover sharp corners. ... Stretch the O-ring evenly. ... Slide, don't roll. ... Assemble so that the female component has a radius around the corner.
How tight should O-rings be?
between 1%-5%To provide an effective seal, the O-ring's inside diameter (I.D.) must be smaller than the piston groove diameter, so that the O-ring is slightly stretched, fitting snugly in the groove. This stretch should be between 1%-5% with 2% as the ideal in most applications.
Are O-rings water tight?
As the name suggests, o-rings are round, ring-shaped sealing devices that sit in a groove between two parts, which are often cylindrical. It is the compression of the two parts that allow the o-ring to form an air or liquid-tight seal. Generally, o-rings can withstand pressure and vibration within their application.
What is the number one cause of O-ring failures?
The most common causes of O-Ring failures include: Improper gland design, allowing for too much or too little compression, not enough for seal expansion and tolerance stack-up. Incorrect O-Ring size. Incompatibility of O-Ring elastomer and environmental elements.
Why are O-rings different colors?
Black o rings were primarily the only coloured o rings around prior to 1987; however, as new materials come onto the market, different colours were required to identify the different materials in use, marking out their visibility and allowing businesses to check their suitability for specific and different applications ...
How much pressure can an O-ring hold?
1,500 psiMost o-rings are designed to operate at pressures up to 1,500 psi. At higher pressures, the material must have enough strength to resist extruding into the clearance gap. The chart shows the recommended combined limits of clearance, gap, material hardness and system pressure differential.
Do O-rings need lubrication?
Lubrication of O-rings is essential for the proper function and full-service life of the seal, but also to ensure the machine, motor, engine, or device in which it is placed does not malfunction from a blown seal. A grease or oil application at assembly helps to protect the O-ring from damage during use.
How do you get rubber O-rings to stay in place?
Using a lubricant helps the O-ring slide easily into place. Ease O-rings Over Threads: O-rings are often mated with threaded parts. The threads can easily tear the rubber O-rings. Covering the threads with masking tape during installation and using an assembly lubricant can help protect the O-ring from nicks and tears.
Can you use petroleum jelly on O-rings?
1:082:41Can I Use Vaseline On My O-Rings? - YouTubeYouTubeStart of suggested clipEnd of suggested clipThe petroleum jelly just eats away at the rubber. And it caused them to deteriorate quicker and failMoreThe petroleum jelly just eats away at the rubber. And it caused them to deteriorate quicker and fail. So you want to use something silicone or Teflon base to lubricate the o-rings keep them soft.
How does an O-ring seal work?
How does an O-Ring seal? Seals prevent fluids from escaping through the gaps in mating pieces of hardware. The O-Ring sits in the middle of a gland when it’s at rest, but as pressure begins to rise in the sealing system, the O-Ring shifts to the opposite side of the pressure.
How many pages are there in the O-Rings manual?
To learn more about applications where O-Rings will perform, download our detailed guide to O-Rings. This 36-page document deals with O-Rings’ technical performance characteristics, materials, chemical and temperature compatibility, hardware considerations and failure modes.
What is an O-ring made of?
O-Rings can be made from plastic or metal, but for the purposes of our blog, we’ll focus solely on rubber – or elastomeric -- O-Ring design. An O-Ring, also known as a “torus,” works in tandem with the glands in which they are installed. The gland is normally cut from the metallic hardware, and works with the O-Ring to seal.
When was the O-ring invented?
The Fundamentals. Technology is always moving forward, but some things stand the test of time. One of those things is the O-Ring, which was first patented in 1896.
What is an O-Ring?
An O-ring prevents leaks by creating a durable, moisture-resistant seal that locks pressurized gas and water inside a system. O-rings seal by being compressed between two joined fittings, preventing any air or outside moisture from entering the closed system.
O-Ring Material Types
O-rings are available from a variety of materials, with each suiting specific application types. Common O-ring materials include:
How do you use an o-ring?
Simply put, an o-ring seal is comprised of an elastomeric circular cross-section into a designed o-ring groove, providing an initial compression.
What happens when a ring is extruded?
With increasing pressure, ring deformation will be exaggerated, ultimately extruding a section of the ring into the extrusion gap. If the extrusion gap is too large, the seal will fail after it is completely extruded from the high pressure.
What is diametric squeeze?
The diametrical squeeze provides a frictional force between the o-ring and the groove that holds it in the installed position. Engineered to deform, the rubber compound flows up to the extrusion gap, completely sealing it against leakage, until the pressure applied is sufficient enough to overcome the frictional forces and deform the o-ring into the small extrusion gap (assuming the rubber has reached its limit of flow under pressure, further increase of force will result in failure by shear or extrusion).
How does O-ring stretch affect seal compression?
O-Ring stretch affects the seal compression by reducing the cross-section, which reduces the sealing potential of the o-ring. At zero or very low pressure, the natural resiliency of the rubber compound provides the seal. Seal performance may be improved by increasing the diametrical squeeze.
Why increase groove depth?
At the other end of the temperature scale, it may be advisable to increase the groove depth slightly to avoid excessively squeezing the ring at working temperatures. This effect can be significant at extreme temperatures because the coefficient of thermal expansion of elastomers is higher than that of metals.
What happens when you apply pressure to an O-ring?
When enough force is applied, the o-ring will move toward the low-pressure side until it contacts the side of the groove. Additional pressure or force will deform the o-ring toward the extrusion gap. The o-ring will initially deform into a “D” shape. This deformation will increase the surface contact area 70-80 percent of the initial cross-section. The surface contact area of an o-ring under high pressure is roughly twice that of the original geometry at zero pressure.
What is the initial force of a groove?
The groove is designed to provide an initial force on the seal across one axis in the range of 7-30 percent. This compressive force is usually perpendicular to the force being applied, resulting in free volume in the groove on the other axis.
What is diametrical compression?
The diametrical compression presents a rubbing force amongst the O Ring and the groove that keeps it in the fixed setting. O Rings are designed to deform, the elastomer element runs up to the extrusion gap, entirely sealing it from leakage, until the stress implemented is adequate enough to conquer the rubbing constraints and deform the O Ring into the little extrusion gap (presuming the elastomer has obtained its restraint of flow under stress, additional increase of force will cause collapse by extrusion or trim).
How does elongation affect seal squeeze?
O Ring elongation affects the seal squeeze by lowering the cross-section, that lessens the sealing capacity of the O Ring. At a very little stress, the natural resistance of the elastomer element ensures the seal. Seal productivity may be enhanced by the growth of the diametrical compression.
What happens to an O ring when it is extruded?
If the extrusion gap is too big, the seal will collapse after it is entirely extruded from the high stress. Upon release of the stress, the elasticity of the elastomer element allows an O Ring to go back ...
Why is the diametrical compression of a seal bigger?
This enhances will be even bigger due to a broadening of the elastomer, because of the heat from the liquid being sealed and the conformity of the materials.
How much force does an O ring exert?
While this situation continues, the O Ring will remain to operate routinely and efficiently up to a number of hundred pounds of force, presuming the O Ring chosen is the right size and the groove is engineered to the adequate size.
What direction does the O ring travel?
When sufficient force is exerted, the O Ring will travel in direction of the low-stress side until it reaches the side of the groove. Further force or stress will deform the O Ring in direction of the extrusion gap. The O Ring will primarily deform into a D shape.
Why enhance groove depth?
At the other end of the temperature range, it may be recommended to enhance the groove depth moderately to prevent overly compressing the ring at functioning temperatures. Due to the modulus of thermal broadening of rubbers is higher than that of metals, this effect can be substantial at rigid temperatures.
How do O-ring seals work?
Whether sold individually, in large wholesale batches or - as is increasingly common - as part of a highly flexible range of o-ring kits, the basic form and role of o-rings are generally the same across the board.
What is the strength of an O-ring seal?
One of the key strengths of an O-ring-type seal is that after the parts it joins are disconnected and the compression forces acting on it are removed, it will return to its original shape. Over time, repeating this process will start to have an effect on the resilience and uniformity of the materials and the torus shape of the seal, and ultimately the o-ring will need swapping out for a new one if the seal is to remain tight.
What is an O-ring?
You could argue that the o-ring is a bit of a ‘living fossil’ in terms of manufacturing components. They were first brought to market way back at the dawn of the 20th century - and yet, for all their absolute simplicity and the very basic nature of the role they perform, they’re still incredibly widely used today.
What is the difference between static and dynamic O-ring seals?
A static O-ring is any o-ring designed to contact with two or more surfaces that do not move relative to one another, whereas a dynamic O-ring is one that helps form a seal between moving parts.
Why are O rings unreliable?
O-ring seals for CO2. Carbon dioxide often presents an issue for many types of o-rings, as softer materials have a tendency to absorb the gas over time and swell up. This can lead to an unreliable seal in the short term, and over time the CO2 will actually cause the o-ring to start to break down from within.
What is the process of making O rings?
O-ring manufacture usually relies on techniques like compression, transfer or injection moulding, machining, or extrusion. There are any number of high-performance materials used in the production of o-rings, ranging from nitrile and silicone rubber to fluorocarbons, metals and more.
What material is used for o-rings?
There are a number of popular high-temperature o-ring material choices, including nitrile, hydrogenated nitrile, silicone rubber, polyacrylate and more. Securing the best choice in any given scenario will generally be a balancing act between the specific operating temperature needed, and the most economical material option at that performance point.
The Basics of Backup O-Rings
Backup O-rings are designed to protect against leaks in the event that the main O-rings fail. All backup O-rings are used in conjunction with a main O-ring. They simply serve as a failsafe. If the main O-ring fails, the backup O-ring will ensure that fluid or gas doesn’t leak out of the machine with which it’s used.
How Backup O-Rings Work
All O-rings feature a circular shape, and they are all made of an elastomer that’s able to withstand heat and pressure. Backup O-rings are no exception. The main difference is that backup O-rings will only be exposed to the liquid or gas flowing through the machine if the main O-ring fails.
In Conclusion
For an added level of protection against leaks, you may want to use a backup O-ring. It will give you peace of mind knowing that if the main O-ring fails, the machine won’t leak liquid or gas. The backup O-ring will act as a secondary seal to protect against leaks.
