 Balloon volumetric compliance

Balloon volumetric compliance is the local change in balloon volume per change in a specified pressure difference, with the mechanical state and other conditions defined:It has units of volume per pressure. It differs from diameter response $\mathrm{d}D/\mathrm{d}p$ in a balloon pressure-diameter curve and from a fractional volume response $(1/V)\mathrm{d}V/\mathrm{d}p$.

For an illustrative cylindrical region whose length can also change,The second term vanishes only when length is held fixed. A diameter-only observation does not otherwise determine the whole volume response.

The Nipro chart gives $2.00$ and $2.16\mathrm{mm}$ for its nominal $2.00\mathrm{mm}$ balloon at labeled rows $6$ and $10\mathrm{atm}$.^[ref] Using those diameters in a chosen fixed-length $10\mathrm{mm}$ cylinder gives the finite-interval estimateThe assumed cylinder is not a measured manufacturer balloon volume. The calculation illustrates why a finite volume change differs from substituting one endpoint diameter into a local derivative.

A balloon compliance fixture correction separates the balloon from the measurement apparatus. In a simple quasistatic model where both experience the same pressure increment, measured injected-volume response can be $C_{\mathrm{measured}}=C_{\mathrm{balloon}}+C_{\mathrm{fixture}}$. A blank or independently characterized fixture is needed before assigning the entire response to the balloon.

Pressure reference, external constraint, loading history, temperature and equilibration also belong to the definition. Hysteresis can give different paths on inflation and deflation. Compliance describes a response in the stated regime; it does not alone supply a rupture pressure or a failure probability.