Pipelines: What is the difference between critical and non-critical interfaces? : Are AVTUR buffers different from interfaces?
No, they are there to separate one product from another, one of them usually being AVTUR. AVTUR has a high purity specification. Consequently, the buffers are large - 100,000 litres (but only 50,000 litres on Government Pipelines Secure System (GPSS)).
AVTUR is kerosene but is fully rebated. AVTUR is by definition not only a high specification of kerosene, but is delivered as an aircraft fuel. Thus although the product is after the duty point, duty remains to be accounted for on the buffer.
The buffer is either treated as an interface or marked as kerosene (MKO) and the duty accounted for at that rate.