in case of ASTM D 2240, it was specified to use 1kgf for A type, 5kgf for D Type, because the Durometer of rubber can have some individual errors depending on the loads and speed.
his Tester has been produced based on the standards. Therefore, hardness measurement can be accurate.
ASTM D 2240 (load is specified) ISO 7619(speed is specified: Max 3.2m/s)