Since it relies on the ability of the fluid or gas to move the float, the scale on a given Glass Tube Rotameter is only accurate for a given substance at a given temperature. The main attribute that is important is the density of the fluid; however, viscosity can also be important. The ideal design of the float is not sensitive to viscosity; however, this can rarely be verified from the manufacturer's specifications. Separate Glass Tube Rotameters of different densities and viscosities can be used, or multiple scales can be used on the same rotameter.

　　Since the operation of the rotameter depends on the gravity of the operation, the rotameter must be oriented vertically. If the direction deviates significantly from the vertical direction, it will cause serious errors.

　　Due to the direct flow indication, the resolution is relatively poor compared to other measurement principles. The reading uncertainty gets worse as it approaches the bottom of the scale. The oscillation of the float and parallax may further increase the uncertainty of the measurement.

　　Since the float must be read through a flowing medium, some fluids may obscure the reading. A sensor may be needed to electronically measure the position of the float.

　　The Glass Tube Rotameter is not easily adapted to machine readings; although a magnetic float that drives the follower outside the tube can be used.

　　The manufacturing size of the Glass Tube Rotameter is usually no more than 6 inches/150 mm, but sometimes a bypass design is used on very large pipes.

　　Panel Flow Meter is also our product, welcome to consult and purchase.