Documents in this section
4.1 Comparing Test Results with Limit Values
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Fuel Delivery Quality Specifications
Fuel should be ordered and delivered to one of a number of product quality specifications. ISO 8217 is a typical example of such a specification. The SE specifications are often used incorrectly and the limits applied in an arbitrary fashion. This could be reduced with the help of proper tools for interpretation.
The analyses presented here deal with the ISO 8217:1996 specification and the rules of interpretation. When the reported test results exceed the specification limit, there is often a judgement made, without an understanding of the limitations of the testing, that the fuel is out of specification. Frequently, the claim is unwarranted and the fuel is on spec despite the high test result.
There are at least two significant limitations to the testing of residual fuels - the test method used and the equipment/laboratory itself. As in any measurement, all tests are subject to tolerance factors. The allowable tolerance in a test or technique is referred to as the ‘’statement of precision’’ and some tests are significantly less accurate than others. In recognition of this, ISO 8217:1996 states:
“The test methods specified in clause 6 all contain a statement of precision (repeatability and reproducibility). Attention is drawn to ISO 4259:1992, clauses 9 and 10, which cover the use of precision data in the interpretation of test results, and this method shall be used in cases of dispute.’’ The Process
Fuel should be ordered and delivered to one of a number of product quality specifications. ISO 8217 is a typical example of such a specification. The SE specifications are often used incorrectly and the limits applied in an arbitrary fashion. This could be reduced with the help of proper tools for interpretation.
The analyses presented here deal with the ISO 8217:1996 specification and the rules of interpretation. When the reported test results exceed the specification limit, there is often a judgement made, without an understanding of the limitations of the testing, that the fuel is out of specification. Frequently, the claim is unwarranted and the fuel is on spec despite the high test result.
There are at least two significant limitations to the testing of residual fuels - the test method used and the equipment/laboratory itself. As in any measurement, all tests are subject to tolerance factors. The allowable tolerance in a test or technique is referred to as the ‘’statement of precision’’ and some tests are significantly less accurate than others. In recognition of this, ISO 8217:1996 states:
“The test methods specified in clause 6 all contain a statement of precision (repeatability and reproducibility). Attention is drawn to ISO 4259:1992, clauses 9 and 10, which cover the use of precision data in the interpretation of test results, and this method shall be used in cases of dispute.’’ The Process
- Value specified - on ordering
- Value tested - on delivery
- Precision data - apply test results
- What can be used?
- Debunker if all else fails.
