What is a disadvantage of Thope tube flowmeters?

The effect of gravity is indeed a significant disadvantage associated with Thope tube flowmeters. These flowmeters are designed to measure gas flow by relying on a float that rises and falls within a tapered tube as gas flows through it. However, their accuracy can be influenced by the orientation of the device because gravity affects how the float behaves within the tube. When a Thope tube is not perfectly vertical, gravity can cause the float to give inaccurate readings, leading to potential miscalculations of gas flow rates. This susceptibility to the force of gravity makes these devices less reliable in certain positions or setups compared to other flow measurement systems that may be less affected by orientation.

In contrast, while high cost, complex calibration, and fragile construction can be considerations for Thope tube flowmeters, they do not uniquely define a fundamental operational disadvantage as gravity does. Thus, the effect of gravity presents a practical challenge that can directly impact their functional efficacy in varying situations.