Contents
How much force does it take to compress an O-ring?
The expected range of force needed to compress an oring 20% with a 0.070” diameter cross section (purple) that is 50 durometer is between 4.5 and 14 pounds per linear inch.
Are O-rings compressible?
Compression set When that force decays entirely, the O-ring will retain its squeezed shape even when it is no longer squeezed. Compression set is a measure of this decay, expressed as a percentage. When compression set reaches 80 percent, most O-rings are in danger of losing their ability to seal.
How much should an O-ring compression?
An O-ring requires almost two and a half times more load force to compress to 40 percent than it does to 25 percent. This level of compressive load could crush or deform lightweight or fragile mating components.
What is O-ring compression set?
The amount of material that fails to return to its original size is called a compression set. This type of failure is common to both static and dynamic seals. Compression set failure produces flat surfaces on both sides of the O-ring’s cross-section, which reduces its sealing potential.
What Viton 75?
VITON® 75 O-Rings BS425 to BS475 Cross Section 6.99mm Fluorocarbon elastomers are highly fluorinated carbon-based polymers used in applications to resist harsh chemical and ozone attack.
How do you choose an O-ring diameter?
Place the O-ring on a clean, flat, level surface. Determine the inside diameter by using a ruler to measure from one inner edge to another. Use a ruler to measure the diameter, from one outer corner of the O-ring to the other outer corner. Finally, measure the cross-section.
Why do O-rings fail?
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.
How do I know what size O ring to buy?
How to Measure O-Rings
- Place the O-ring on a clean, flat, level surface.
- Determine the inside diameter by using a ruler to measure from one inner edge to another.
- Use a ruler to measure the diameter, from one outer corner of the O-ring to the other outer corner.
- Finally, measure the cross-section.
What causes O-ring failure?
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. Improper O-Ring installation. Inadequate O-Ring lubrication.
How do you size an O-ring?
What are the different types of O rings?
Some of the common types of O-ring materials include PTFE, Nitrile (Buna), Neoprene, EPDM Rubber and Fluorocarbon (Viton). Silicone and Kalrez® O-ring materials are also widely used, especially in high temperature applications.
How to calculate the O-ring compression force?
To use the eHandbook chart, you will need to know the O-ring midline circumference in inches, the O-ring cross section in inches, and the durometer. First find the chart for the O-ring cross section size: 0.070”, 0.103”, 0.139”, 0.210” and 0.275”.
Where do I find the O-ring compression band?
Next, locate the O-ring compression or squeeze on the x-axis of the chart. Moving vertically to either the 70 or 90 durometer band, you will find the expected range of load in pounds per linear inch of O-ring.
What’s the best way to compress an O ring?
If you have access to a machine shop make a .060 groove in a block of wood, aluminum, plastic etc. Lay an O Ring in the groove set the whole thing on a bathroom type scale. Force a 1″ wide flat hard object down until it compresses the O-Ring (.010) enough to make full contact.
Which is the correct description of an O-ring?
An O-ring is a doughnut-shaped object or torus. The opposite sides of an O-ring are squeezed between the walls of the cavity or “gland” into which the O-ring is installed. The resulting zero clearance within the gland provides an effective seal, blocking the flow of liquids or gases through the gland’s internal passage.