Choosing the right elastomer seal can be a difficult task when it comes to actuators, pneumatic applications and control valves. The real challenge is choosing the correct elastomer material to withstand dynamic motion without changing the seal’s original shape.
We have put together five top tips and considerations to keep in mind when choosing a sealing solution for actuators and control valves:
1. Do not compromise on quality
Value engineering is a common term that manufacturers tend to dislike. With certain things, it is easy and a good idea to value engineer materials to a cheaper product. Sealing solutions do not fall into this category. The actual cost of seal failure is a lot more expensive than purchasing a high-quality seal in the first place.
Seals that need to be replaced due to failure will incur additional costs during downtime, including lost productivity and clean-up costs if leakage or contamination has occurred.
2. Consider the operating environment
This is one of the most significant factors when selecting a suitable elastomer material for your sealing solution. Seals have an important job to do, and it is essential that the elastomer material is selected based on the operating conditions to provide optimum performance.
We provide over 300 grades of elastomer material, spanning 13 types of rubber polymer, all offering different performance characteristics, for different applications, across different industries.
Considerations such as temperature, pressure, media, stroke length and groove type need to be taken into account, especially in high-risk applications, as failure could have catastrophic consequences.
3. Focus on material selection
Once you have determined the operating environment and fully understand the application, it’s time to select the correct material for the operating environment. Most elastomers have strengths and weaknesses, some perform better than others in certain conditions depending on the chemical media and temperature they’re exposed to.
For example, the most popular elastomer materials for industrial applications, where actuators and pneumatic equipment is regularly used, are:
EPDM - with fair mechanical properties and ability to operate in temperatures from -60°C through to 288°C, they offer a cost effective, versatile solution and are resistant to chemical attack. However, it should be noted that they are not compatible with applications with mineral and synthetic lubricants, and hydrocarbon fuels.
FKM - this rubber material includes copolymer, terpolymer and tetrapolymer versions. An FKM elastomer is a highly fluorinated polymer that provides a broader range of chemical resistance and exhibits very low gas permeability. FKMs can withstand temperature extremes from -50° through to 250°C.
4. Consider the key reasons seals fail and work to minimise that risk
There are several common issues that repeatedly come up when assessing why seals fail. For example:
- Chemical attack - some chemicals will react with certain elastomer types resulting in seals that become soft, tacky, hard or brittle
- Chemical swell - this is caused by the ingress of media into the elastomer
- Abrasion - this is caused by repetitive contact between the seal surface and the housing, causing excessive friction from improper lubrication
- Compression set - physical and chemical changes can occur to an elastomer that prevent it from returning to its original shape, resulting in reduced sealing force
- Extrusion and nibbling - high stresses, usually as a result of increased pressure, can force the seal into the clearance gaps causing damage to the sealing surface
- Improper installation - installation damage covers a wide range of faults, including the seal being cut, pinched, twisted, stretched or improperly lubricated
- Thermal degradation - the temperature of the application has exceeded the maximum temperature capability of the elastomer.
5. Choosing the right manufacturer
There are a lot of things to consider when choosing the right elastomer seal for actuators, pneumatics and control valves. It is important to work with a manufacturer with expertise in the sealing industry. An expert team should be able to guide you through the proper specification of elastomer materials and provide you with relevant technical data.
The main characteristic to look out for in your elastomer seal manufacturer is recognised quality standards and industry-specific certifications. This will ensure you’re working with the right partner with knowledge and expertise related to your industry.