The NTB-492 is a popular test across Europe and other parts of the world. It is a similar test to a combination of ASTM C1202 and ASTM C1556. ASTM C1202 and NTB-492 will both provide the indication of the quality of your concrete and its ability to prevent chloride penetration. ASTM C1202 is a quicker test and slightly less complicated.  The Perma is not compliant with the NTB 492 because with this equipment you cannot change the applied voltage used in the test.