They are the most common type of rotameters which are used extensively not only in industries but also in pilot plants and labs to measure flow rates of wide variety of fluids, both liquids and gases.
One of the advantageous functionality is its ability to purge the fluid if the condition of the system is not proper. It is useful for low flow rate, high pressure and corrosive applications.
It is used in automated systems where the applications require quite opaque liquids at aggressive conditions. It is mostly used in high pressure applications.
Reference:- instrumentationtools , automationforum , bucksales. July 1, May 23, May 22, Rundown Tank Purpose and Working. Gas Turbine Working and Types. Steam Turbine Working and Types. What is Pump Priming? Centrifugal Pump Start up Procedure. Types of Pumps and Applications. Types of Compressors. Different Types of valves. Needle valves Introduction. Deaerator working principle, Types and Process Control. Inst Tools. A rotameter is a device that measures the flow rate of liquid or gas in a closed tube.
It belongs to a class of meters called variable area meters , which measure flow rate by allowing the cross-sectional area the fluid travels through, to vary, causing a measurable effect. The drag force for a given fluid and float cross section is a function of flow speed squared only.
A higher volumetric flow rate through a given area increases flow speed and drag force, so the float will be pushed upwards. Floats are made in many different shapes, with spheres and ellipsoids being the most common. When the fluid enters in the metering tube, the float moves upwards, increasing the flow area of annular orifice. Float is pushed upwards, until, the lifting force produced due to pressure difference across its upper and lower surface becomes equal to weight of float.
Now, if the flow rate increases, the pressure difference and hence, lifting force increases temporarily. Due to this, float moves upward and increases the area of annular orifice, so that, the Increased lifting force will decrease and fluid force will be equal to weight of float. Thus, the pressure difference remains constant by changing the area of annular orifice in proportion to the flow rate.
Every float position corresponds to one particular flow rate for a fluid of given density and viscosity. Calibrated scale marked on the glass tube provides the direct indication of flow rate.
Material used for float: Heavier metals like Stainless steel , Gun metal, Brass etc. Material used for tube: Non-corrosive materials such as Glass, plastic etc. Working Principle of Radiation Pyrometer Radiation pyrometer works on the…. A flow nozzle operates on the principle of variable head type flow meter.
Differential pressure…. Bimetallic thermometers use two fundamental principles: All metals expand or contract with change in temperature. We provide tutoring in Electrical Engineering.
View all posts by Electrical Workbook. Your email address will not be published. A A linear scale is graduated or marked on the outer periphery of glass tube. Working of Rotameter Fluid whose flow is to be measured enters the tube from bottom, then moves upward and escapes through the top. Characteristics of Rotameter Simplicity of construction and low cost.
Possibility of remote indication and record. Essentially a linear scale with most of the meters. Easy to install. Advantages of Rotameter Pressure loss is nearly constant and small. It can handle any corrosive fluid.
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