ISO 844:2014 specifies a method of determining a) the compressive strength and corresponding relative deformation, or b) the compressive stress at 10 % relative deformation, and c) when desired, the compressive modulus of rigid cellular plastics.
There are two procedures:
– Procedure A employs crosshead motion for determination of compressive properties. Procedure A is intended to be used when compressive stress at 10 % relative deformation has to be determined.
– Procedure B employs strain measuring devices mounted on the specimen (contact extensometer) or similar device which measures directly sample deformation. Procedure B is intended to be used when compressive modulus has to be determined.
NOTE : This test method and ASTM D1621 are technically equivalent.