What to Do If the Pointer of a Metal Tube Rotameter Drifts?
A metal tube rotameter is a precision instrument that plays an indispensable role in measuring flow parameters of liquids, gases, and other media. As a high-precision measuring device, its pointer must operate normally to ensure the accuracy of measurement results. However, during the actual use of a metal tube rotameter, issues such as pointer vibration or zero drift may sometimes occur. What are the causes behind this?
When there is no external vibration and the environment is stable, if the pointer of the metal tube rotameter vibrates, it is usually because the float of the flowmeter is contaminated with impurities or has become dirty. When the float is contaminated, the friction between it and the measuring tube of the instrument increases. This prevents the float from promptly displaying the correct measurement results. Nevertheless, due to inertia, the float will suddenly rise under the buoyancy of the fluid, and then quickly fall back due to pressure effects—this is what causes the pointer of the metal tube rotameter to vibrate.
When this situation occurs, the operator should promptly remove the float of the metal tube rotameter, thoroughly clean the impurities on the float and those inside the measuring tube, and only resume operation after the cleaning is completed.
We have now understood the causes of pointer drift in metal tube rotameters. As a high-precision measuring instrument, incorrect operation during its use can significantly affect the displayed results. Therefore, mastering the correct operation method is key to ensuring more accurate measurement results. So, how should it be operated? What are the operating specifications?
Below is an analysis for reference:
Before installing the metal tube rotameter, check whether the pipeline vibrates. Pipeline vibration will affect the movement of the float, leading to inaccurate measurement results.
After confirming that there is no vibration in the pipeline, install the metal tube rotameter vertically on the pipeline. An inclined installation will prevent the rotameter from correctly displaying the floating height of the float; consequently, it will be unable to calculate the space area above the float, resulting in imprecise measurement results.
Identify the type of impurities in the medium. If the medium contains metallic impurities, these impurities will affect the movement of the rotameter’s float during flow (exerting external forces) and may even cause chemical reactions that render the float non-functional. In such cases, a filter with strong magnetism should be installed to remove metal ions. If there are solid particulate impurities in the pipeline, these impurities will collide with the float during flow, altering its movement trajectory and affecting the physical properties of the medium—ultimately leading to measurement inaccuracies.
When measuring the flow of gaseous media, pay attention to the safety of the outlet discharge. High-speed gas flow, if not decelerated, will cause a strong impact on the surrounding environment. Incorrect placement may pose risks to human health or even lead to more serious hazards.
