Yes, rotameters are affected by changes in pressure. When the pressure decreases, the rotameter will read a lower flow rate. Similarly, when the pressure increases, the rotameter will read a higher flow rate. This is because the rotameter measures the fluid's velocity, and changes in pressure will affect the fluid's velocity. Therefore, it is important to keep the rotameter's pressure at a constant level if you want to accurately measure the flow rate. Learn more about Flow Rate And Pressure Formula, which may help you calculate mass or volume flow.