GOVERNMENT ENGINEERING COLLEGE, BHARUCH. CHEMICAL ENGINEERING, SEMESTER: 5. ENROLLMENT No: Bansari Purohit..(130140105042) Bhakti Patel..(130140105025) Jhanvi Kevadiya..(130140105014)

SUBJECT : INSTRUMENTATION AND PROCESS CONTROL…(IPC) TOPIC : ROTAMETERS GROUP NO: 1

ROTAMETER Rotameter is a variable area meter. Here in variable area meters the pressure drop across the meter is constant and the flow rate is a function of area of constriction / area of flow . Rotameter a variable area meter is described in brief as under:

PRINCIPLE: The pressure drop across the meter is constant and the area through which fluid flows varies with flow rate . OR In other words the pressure drop across the meter is constant and the area through which the flow varies with the flow rate . The area is related to proper calibration , to the flow rate.

CONSTRUCTION:

As shown in the figure it consists of (1) Metering tube ,(2) Float, (3) Rotameter scale, (4) Rotameter installation , (5) Types of rotameter.. All the above terms are explained in detail as under: (1) Metering tube.. It is tapered glass or metal tube set vertically in pipe system with larger end at the top and the smaller end at the bottom . The tube is placed in the metal housing with front side made of glass of observing the scale.

Tubes are made of mandrel and annealed to prevent internal stresses. A float stop is provided at the upper end of the tube to prevent driving out of the float with fluid stream. The meter tube is made of glass for low temperature and pressure fluids . But for high pressure service , metal tubes are used. (2) Float. It is usually made of metals which have density higher than liquid , but they can be made of any corrosion resistsant materials like alluminium,brass,etc.

Float range of rotameter changes with the change in float materials. Ball floats are used in measuring the low flow rates while sharped edge floats are used in measuring relative intensity to viscosity change over a considerable viscosity range. Float is installed in the tube after the meter is mounted in the flow line. It is inserted from the inlet filling and not from outlet filling so as to avoid float damage due to its free fall in the tube

(3) Rotameter scales: Scales are marked on the glass tube or it is mounted close to all metering tube. Scale can be direct reading type or percentage scale is used which show percentage value of actual flow relative to maximum flow. (4)Rotameter installation: Rotameter is installed in the pipe line by means of flanges or threads along with inlet and outlet about 2 geometric degrees so as to center the float in the fluid stream.

(5)Types of rotameter: (a) direct viewing rotameter: In this type , float is viewed directly and its displacement is measured on the scale calibrated in fluid flow rate. This type is used for flowing and clear liquids. (b)magnetically coupled rotameter: In this type float movement is magnetically coupled to the indicating, recording or controlling element . This is also used for ellectrically oe pneumatic transmission of float movement to the remote point.

INDUSTRIAL ROTAMETER

WORKING:

USES: It is widely used in chemical industry for the measurement of flow rates of compressible as well as incompressible fluids. They provide a directing reading of the flow rates. Performance characteristics: 1. Linearity: The volumetric flow rate of fluid through rotameter is proportional to the area. Its scale is nearly linear with the non linearity of about ±5%

ADVANTAGES AND LIMITATIONS: ADVANTAGES: 2. Accuracy: accuracy of rotameter is about ±2% of the full scale reading but longer scale increases the accuracy to ±¼% of the reading. ADVANTAGES AND LIMITATIONS: ADVANTAGES: Rotameter has relatively low constant pressure drop. It can handle almost any corrosive liquid . It can be compensated for changes in fluid density and viscosity. They are relatively cheaper.

limitations: They have good accuracy particularly at low flow rates. It must be vertically mounted in the pipe line. Glass tube rotameters are not so rugged due to presence of glass tube. They are used in limited to relatively low temperature ranges.

Thank you…