  An SPIV experiment using two orthogonal planes simultaneously was performed
in the LML boundary layer facility to specifically measure all of the
derivative moments needed to estimate the dissipation rate of the Turbulence
Kinetic Energy. The Reynolds number was $Re_\theta = 7500$ or $Re_\tau = 2300$.
A detailed analysis of the errors in derivative measurements was carried out,
as well as applying and using consistency checks derived from the continuity
equation. The random noise error was quantified, and used to ``de-noise'' the
derivative moments. A comparison with a DNS channel flow at comparable Reynolds
number demonstrated the capability of the technique. The results were further
validated using the recent theory developed by George and Stanislas 2020. The
resulting data have been extensively used in parts I and II of the present
contribution to study near wall dissipation. An important result of the present
work is the provision of reliable rules for an accurate assessment of the
dissipation in future PIV experiments.
