a secondary verification material.
11.4 When the CFPP values obtained using a verification
material deviate by more than the test repeatability (see 15.2),
or an unacceptable statistical quality control bias is observed,
check the condition and operation of the apparatus to ensure
conformity with the specification as stated in this test method.
The manufacturer’s instruction manual should provide guidance on ensuring that the apparatus is correctly set up and
calibrated.