When choosing a seal for your operation, it’s hard to decide which company has the best. At Real Seal, we routinely put our seals through strenuous ASTM testing to ensure consistent quality. ASTM is an international standards organization that originated in the USA as a way to hold manufacturers to a higher standard of quality and reliability. By employing these standards, Real Seal is able to prove the durability of our seals to a variety of elements. Various tests designed by ASTM to ensure this level of quality include these various properties and more:
Compression Set
Compression set is how deformed a material becomes after a certain amount of force is applied to the material. This is especially important for seals so that as they undergo the various pressures of sealing, they are able retain the shape necessary for sealing the surface they are adhered to.
ASTM D395 is one of the most common methods of testing for compression set. There are two methods under this protocol. Method A tests compression as the percentage of thickness of an object, in this case the seal, after being exposed to a constant force for a set time and temperature, then giving it thirty minutes to recover. In method B, the material is compressed by 25% and then a measurement is taken. Both of these methods allow for the seal to be tested for its ability to reform after being compressed by a force.
Hardness
Another important factor in how durable any given seal is the hardness of the seal. The harder the seal, the more resistant it is to impact, as well as being able to maintain its form better, although harder materials can crack or break.
ASTM D2240 uses a durometer to determine the hardness of rubber and plastic materials used to make o-rings and other seals. This test is done by measuring how much a material is penetrated or “pushed in” by a specified indenting implement. Hardness is drawn from a scale known as Shore hardness; Shore A for softer materials, and Shore D for harder materials.
Heat Resistance
Many industrial applications of seals put the material under the intense strain of heat. Heat can warp and damage the material over time if it isn’t chosen correctly or of the highest quality.
ASTM D573 tests the effects of increased temperature on a seal. The seal is placed in a hot oven or other heating device and then the hardness, elasticity, or other materials are then tested. Any changes in these properties can indicate deterioration of the material. These tests are often specified to the conditions a given application will place upon the seal, ensuring that it won’t degrade too quickly and cause some kind of catastrophic failure.
Tear Strength
Perhaps one of the most important properties for dynamic operations is the tear strength of a material. The tear strength of a material is its ability to resist being torn apart by a force. Damage by heat, friction, and other forces can lower the tear strength of a material, so those aspects are important, as well.
ASTM D624 sets the standards for testing a material’s strength divided by its thickness at resisting forces pulling it apart with a nick to lead the tear. A tensile test machine is clamped to two ends of the material and then pulls. The maximum force required to tear the material is used to determine this property.
Fatigue Limit
Fatigue limit is another important property for dynamic operations with cyclic motion. A material’s fatigue limit is its ability to withstand the stress of undergoing this kind of cyclical strain. This is best tested by applying the same type of force which will be applied to the seal during its operation for a certain number of cycles to see if there are any tears or changes its properties such as tear strength and hardness.
Real Seal’s Commitment
Real Seal is committed to testing and ensuring that a product will withstand the pressures it will undergo during operation. ASTM and ISO guidelines ensure that their seals will be put under the right amount and type of strain to maintain a superior product. To ensure that the seals you use for your operations are durable and of the highest quality, contact Real Seal today!
