The parameters are based on the following formulas:
Calculation of Vn
(Δpnom = nominal pressure)
$$V_{n} = \sqrt{\frac{300\ \lbrack Pa\rbrack}{\mathrm{\Delta}p_{\text{nom}}\lbrack Pa\rbrack\ }}$$
300 Pa is the upper limit of the operating range of the differential pressure sensor. The nominal pressure is the differential pressure in the VAV box at a given nominal volume flow, determined by the OEM specification.
Min. and max. volume flows (Vmin / Vmax)
$$V_{\min}\lbrack\%\rbrack = \frac{min.\ \ volume\ flow\ \lbrack\frac{m^{3}}{h}\rbrack}{nom.\ \ volume\ flow\ \lbrack\frac{m^{3}}{h}\rbrack} \bullet 100\%$$
$$V_{\max}\lbrack\%\rbrack = \frac{max.\ \ volume\ flow\ \lbrack\frac{m^{3}}{h}\rbrack}{nom.\ \ volume\ flow\ \lbrack\frac{m^{3}}{h}\rbrack} \bullet 100\%$$
Actual relative flow as function of setpoint and min. / max. limits
$\text{FLW\ }\lbrack\%\rbrack = \frac{\text{Setpoint\ }\lbrack\%\rbrack \bullet \left( V_{\max} - V_{\min} \right)\ \lbrack\%\rbrack}{100\%} + V_{\min}\ \lbrack\%\rbrack$
Actual relative flow as function of differential pressure
$$\text{FLW\ }\lbrack\%\rbrack = 100\% \bullet V_{n} \bullet \sqrt{\frac{\mathrm{\Delta}p\left\lbrack \text{Pa} \right\rbrack}{300\left\lbrack \text{Pa} \right\rbrack}}$$
Actual differential pressure as function of actual flow
$$\mathrm{\Delta}p\left\lbrack \text{Pa} \right\rbrack = 300\ Pa \bullet \left( \frac{\text{FLW}\lbrack\%\rbrack}{100\% \bullet V_{n}} \right)^{2}$$