In Plastic Rotameter, the height of the float indicates the flow rate.
Rotameter tubes can be calibrated and indexed with appropriate flow units.
The adjustment ratio of the rotameter is usually as high as 12:1.
The accuracy may reach 1% of the full-scale rating.
The rotameter tube can be made of glass, metal, or plastic.
The pipe diameter ranges from 1/4 to more than 6 in.
In safe applications, such as air or water, the tubes of the rotameter can be made of glass, and in cases where a rupture may cause an unsafe condition, they are equipped with metal tubes.
In addition, for higher pressures and temperatures above the actual range of glass, metal tube rotameters are used.
Solenoid Valve Manufacturer's plastic tube rotameter is a medium-cost rotameter. Moreover, they are very suitable for applications involving corrosive fluids or deionized water.
Almost all rotameters are insensitive to viscosity changes. The most sensitive ones are the extremely small rotameters with spherical floats, while the larger rotameters are less sensitive to the effect of viscosity.
Rotameters including magnetic floats can be used for alarm and signal transmission functions.
Since the flow rate can be directly read on the scale installed next to the pipe, no auxiliary flow reading device is required. However, if necessary, an automatic sensing device can still be used to sense the level of the float and send a flow signal.
For a specific fluid density and viscosity, each float position corresponds to a specific flow rate. Therefore, it is important to determine the size of the rotameter for each application. If the size is appropriate, the flow rate can be determined by matching the position of the float with the calibration ratio outside of the rotameter.
Many rotameters have built-in valves for manual flow adjustment.
Various shapes of floats can be used for various applications. An early float design had grooves, which caused the float to rotate for stability and centering purposes. Because of this rotation of the float, the term rotameter was coined.
Rotameters are usually equipped with calibration data and direct reading scales for air or water or both. In order to determine the size of the rotameter for other services, the actual flow must first be changed to the standard flow. If it is a liquid, the standard flow rate should be the water equivalent in GPM, and when gas is involved, the expected standard flow rate is the airflow rate in standard cubic feet per minute (scfm).
Rotameter manufacturers provide tables listing standard water equivalent GPM and air scfm values. They should also provide usable slide rules, nomograms, or computer software, which are usually required to determine the size of the rotameter.
The main advantages of rotameter are as follows:
Low pressure drop