The water absorption rate for these o-rings is exceptionally low, at less than 0.01%. This value, typically measured as a percentage of weight gain after 24 hours of water immersion (per ASTM D570), signifies a material that is highly resistant to moisture. Such a low rate is a key indicator of a high-performance elastomer designed for stability in demanding environments.
The core takeaway is that a water absorption rate below 0.01% ensures the o-ring will not swell or change its physical properties when exposed to water. This dimensional stability is critical for maintaining a reliable, long-term seal in wet or humid applications.
What This Value Actually Means
The Standard Measurement
The number "0.01" isn't arbitrary. It's derived from a standardized test, most commonly ASTM D570, where a material sample is weighed, submerged in water for 24 hours, and then weighed again.
The result is expressed as the percentage of weight gained from the absorbed water.
Interpreting "<0.01%"
A value this low is near the measurement limit for many materials. It indicates the o-ring is fundamentally hydrophobic (repels water).
This characteristic is typical of high-performance elastomers like FKM (Viton®), FFKM, or Silicone. The material simply does not allow water molecules to easily penetrate its polymer structure.
The Impact on O-Ring Performance
Dimensional Stability is Key
The primary consequence of water absorption is swelling. An o-ring that swells can increase in volume, leading to seal failure.
A low absorption rate ensures the o-ring will maintain its original dimensions and fit precisely within its designed groove, even after prolonged water exposure. This prevents issues like seal extrusion or increased friction in dynamic applications.
Consistent Mechanical Properties
Water absorbed into a polymer can act as a plasticizer, which can alter its physical properties. This may lead to a decrease in hardness (durometer) or a reduction in tensile strength.
Because this material absorbs virtually no water, its mechanical properties remain stable and predictable throughout its service life.
Resistance to Chemical Breakdown
For certain polymers, water can cause a chemical reaction called hydrolysis, which breaks down the polymer chains and degrades the material. This is especially true at elevated temperatures.
A material with very low water absorption inherently has a much higher resistance to this form of chemical attack.
Understanding the Trade-offs
Material Context is Crucial
This excellent water resistance is a property of specific premium materials. You should not assume all o-rings perform this way.
For example, materials like Nylon or certain Polyurethanes can have significantly higher water absorption rates, making them unsuitable for many wet applications despite other desirable properties.
Temperature and Pressure Effects
While the 24-hour test provides a standard baseline, be aware that absorption rates can increase with higher water temperatures and pressures.
However, for a material starting at less than 0.01%, the effect is typically negligible in all but the most extreme conditions.
One of Many Factors
Water absorption is a critical specification, but it's not the only one. Always evaluate it alongside other key factors for your specific application.
These include chemical compatibility, operating temperature range, and compression set to get a complete picture of the o-ring's suitability.
Making the Right Choice for Your Goal
This o-ring's extremely low water absorption makes it a premier choice for applications where moisture is a factor.
- If your primary focus is high-precision sealing in a wet environment: This o-ring is an excellent candidate due to its exceptional dimensional stability.
- If your primary focus is long-term reliability in fluctuating humidity: The material's resistance to property changes ensures consistent performance over the product's lifespan.
- If you are replacing a failing seal in a wet application: This o-ring's superior water resistance likely solves the root cause of failures caused by material swelling.
Ultimately, selecting a material with this level of water resistance provides confidence that your seal's integrity will not be compromised by moisture.
Summary Table:
| Key Performance Indicator | Specification | Importance |
|---|---|---|
| Water Absorption Rate | < 0.01% (ASTM D570) | Prevents swelling, maintains seal integrity |
| Dimensional Stability | Excellent | Ensures consistent fit and performance |
| Material Type | High-Performance Elastomer (e.g., FKM, FFKM, Silicone) | Provides inherent hydrophobicity and chemical resistance |
| Impact on Properties | Negligible change in hardness or strength | Guarantees predictable performance over time |
Need a Seal That Withstands Moisture?
Your application demands reliability. The exceptional performance of these o-rings—with a water absorption rate of less than 0.01%—is the result of precision engineering and high-quality materials.
KINTEK specializes in manufacturing high-performance PTFE and elastomer components, including custom o-rings, for the most demanding environments in the semiconductor, medical, laboratory, and industrial sectors.
We provide:
- Expert Material Selection: Ensuring chemical compatibility and performance for your specific conditions.
- Custom Fabrication: From prototypes to high-volume orders, tailored to your exact specifications.
- Uncompromising Quality: Precision production that guarantees dimensional stability and long-term seal integrity.
Don't let moisture compromise your seal. Contact our experts today to discuss your application requirements and get a solution you can trust.
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