Table 1: Basic Requirements for Establishing Type by Temperature

The class is based on the resistance of the material to swelling in IRM 903 oil after immersion for 70 hours, at a temperature called out by the type. Limits for swelling for each class is shown in the table below.

Table 2: Basic Requirements for Establishing Class by Volume Swell

These letter combinations can often indicate the material polymer. ASTM D2000 breaks down the different rubber types using the following material codes.

Table 3: Polymers Most Often Ued in Meeting Material Requirements

In our example, the "HK" indicates a fluorocarbon would likely meet the requirements for the seal.

M4HK710 A1-11 B38 EF31 EO78 Z1

The “7” portion of the ASTM callout describes the shore A hardness of rubber. In our example, the hardness called out for the rubber is 70 durometer, ± 5. 

M4HK710 A1-11 B38 EF31 EO78 Z1

The last part of the ASTM callout describes testing that is required for the materials to meet. The testing types can be broken down into two parts. The letter portion of the suffix for the testing describes the type of tests required for the compound. A list of the testing types is shown below.

The second portion of the suffix, the numbers, indicate the temperature and duration at which the tests must be conducted. Take for example the difference between B37 and B38 testing.

Both are 22 hour compression set tests . However, B37 is set at 175°C, while B38 is set at 200°C. So, tests with the same letter portion as part of the suffix will be the same type of test, but if they have different numbers in the second part of the callout, they will have different temperatures or durations for the testing. 

So, for our example, our compound will have the following compound test requirements:

• A1-11 = Heat resistance test for 70 hours at 275°C
• B38 = Compression set testing for 22 hours at 200°C
• EF31 = Fuel C fluid testing for 70 hours at 23°C
• E078 = Service fluid No.101 fluid testing for 70 hours at 200°C
• Z1 = Could be any special requirement not covered in ASTM D2000, such as the color of the rubber or fluid tests not standard to ASTM D2000.  A common Z callout is to change the durometer from 70 or 80 Type A to 75 ± 5

To summarize, the ASTM callout used as our example will call out for the following type of rubber.

M4HK710 A1-11 B38 EF31 EO78 Z1

This ASTM callout requires a 70 durometer fluorocarbon rubber, with a minimum required tensile strength of 10 MPa. It also requires Grade 4 heat age, compression set, fuel C fluid, and service fluid No 101 testing, with an additional special requirement not covered in ASTM D2000.

Other requirements can be compiled into an ASTM D2000 callout following this standard formula, which can then be easily interpreted by someone familiar with the standard.

For more information about ASTM D2000, or any Parker seals, contact Gallagher Fluid Seals today.