^{32}If we know that the plummetâ€™s weight will remain constant, its drag area will remain constant, and that the force
generated by the pressure drop will always be in equilibrium with the plummetâ€™s weight for any steady flow rate, then the
relationship F = PA dictates a constant pressure. Thus, we may classify the rotameter as a constant-pressure,
variable-area flowmeter. This stands in contrast to devices such as orifice plates, which are variable-pressure,
constant-area.