FPF.Preface:16.5.5.2 - Form and interpret the pressure assessment

Keep P17 as the entity the resulting assessment concerns. State the regime and measurement occasion as conditions of its claims. The reference scheme uses kPa, an absolute pressure datum, the relation between gauge and absolute pressure, and the meaning of the stated bounds. The claim content includes the applicable limit, the converted pressure interval and what follows for this comparison. The manual states the limit; the configuration record states its applicability to P17; the measurement record supplies the indication and uncertainty assumptions; the calculation derives the comparison from those premises.

For these readings, absolute pressure equals gauge pressure plus local atmospheric pressure: p_absolute = p_gauge + p_atmosphere. Apply that relation to the stated intervals:

• gauge pressure lies in [190, 200] kPa;
• atmospheric pressure lies in [98, 102] kPa absolute;
• absolute pump pressure therefore lies in [288, 302] kPa.

For a conservative enclosing interval, adding lower endpoints and upper endpoints requires no independence assumption. It does require the stated intervals and addition relation to apply together. The stipulated relation admits the central values, which give 295 kPa absolute. The enclosure’s upper endpoint exceeds the limit while its lower endpoint does not. This enclosure therefore establishes neither compliance nor a violation. Distinguish an enclosure spanning a threshold from two feasible cases with different answers: the enclosure alone leaves the threshold question unresolved, without proving that both outcomes are possible. Comparing only the central value of 295 kPa with 300 kPa would lose the reason the uncertainty matters.

The resulting episteme is a coherent answer: under these inputs, compliance is unresolved. It tells the decision-maker what cannot be concluded and why. It is useful even though it does not authorize operation. A measurement that narrows the pressure interval enough to resolve the comparison, a changed operating regime, or a governing decision that permits reliance under residual uncertainty are different next possibilities. Such a decision must identify the uncertainty it permits and the scope of that permission; this example supplies no authority to make it.