ORING AS568 AS251
ID 129.77 x CS 3.53
Material : Silicone 70 Shore
Silicone O-Rings are sometimes referred to VMQ O-Rings.
Silicone elastomers are an excellent material due to its outstanding resistance to extreme range of temperature ranging from (-59`C to 232`C) and it has good retention of compression and flexibility.
In addition Silicone perform excellent resistance to ozone, oxygen, moisture and water swell. Last of all, Silicone has and produces very low odour and taste elastomer therefore making it the right material to be used in food and beverage, and medical industry.
Temperature Range (Dry Heat)
Low: -75`F / -59`C High: 450`F / 232`C
Overview on Application Rating for Material Silicone
Oils & Grease - Fair
Tear Strength – Poor
Fuel Resistance - Poor
Heat Ozone & Aging Resistance - Excellent
Water Swell Resistance - Excellent
Abrasion Resistance - Poor
Other than the size and material type, there is one final option that you need to take in consideration. And that is the Durometer. Durometer are being classified as an industry standard to measure the elastomer hardness. Durometer is measured and listed in accordance with “Shore A” scale. Typical standard hardness for the elastomer are 70 shore, 75 shore and 90 shore to choose from depending on the material that you are using. The higher the value of the shore indicates that the material you are using is harder. Durometer is also generally stated and accepted with a “+/- 5” tolerance. Silicone O-Rings the standard nominal durometer is 70 Shore.
O-Rings and rubber seals are generally used for:
· Applications that require resistance to OIL
· Applications that are required to work in low temperatures (-0°C)
· High performance Fuel systems that requires strictly no leakage
· General Industrial Use
Tips for installation of an O-ring
O-rings need to be installed properly for a perfect fit and sealing. It is important that you install the O-ring in a prescribed manner to ensure your application continues to function properly. You will also ensure you increase the life of the application.
So how do you install an O-ring?
The process of installing an O-ring into a male gland is an intricate affair that should be carefully undertaken. Glide it along the shaft so as it reaches the gland. At that point, it should easily snap into place. Simple as it might sound, a number of steps will ensure that the O-ring doesn’t get damaged.
If you want to install an O-ring correctly and within a short time, here are steps to follow:
· Covering and lubricating the threading of the shaft
The threading of the shaft has the potential of tearing the rubber seal. Cover the threads using a masking tape and then lubricate them to allow for easy passage of the O-ring. The aim is to have the O-ring slide through without getting torn.
· Don’t force it over sharp corners
That’s a tip that will save you the stress of a torn O-ring. In fact, running the O-ring over jagged or sharp objects could get it torn. You may not be able to notice some of these tears. That’s why you should ensure you prevent them from occurring in the first place.
· Even stretching
You will have to stretch the O-ring over the shaft. Ensure you do it evenly. Pulling from one side is a no-no. If anything, you should stretch the O-ring as little as possible. You will not just get a tighter grip but added security too.
· Don’t roll it down the shaft
Instead of rolling the O-ring down the shaft, slide it. If you spiral wind or roll an O-ring, it cannot be properly installed. It will also not function optimally and can even end up being damaged. If you have a lubricant, apply it on the O-ring and you will keep it rolling.
· Finishing it off
Place the female component in a manner that allows its radius to go around the corner. This should be done when you are finalizing the installation process. Ensure the lead of this component is inside the chamfer. This is how you will be able to guarantee the safety of the O-ring.
For O-rings to perform optimally, they have to be properly installed. It doesn’t just provide secure sealing but also increases the service life of the component together with the application. Don’t compromise on this process.