What is Digital rotameter flow meter
The rotameter and Digital rotameter flow meter are one of the most commonly used instruments for measuring the instantaneous flow of clean fluids such as liquids and gases or vapor; we also call it variable area flow meter.
Local reading Variable area rotameter can only indicate fluids flow rate with flow unit: m3/h, GPM,Nm3/h, kg/h .,etc, it does not need any power supply, while
digital rotmater can not only show flow rate , also total flow and transmit 4-20mA or pulse flow signals for process control.
Digital rotameter flow meter instrument has the advantages of simple structure, convenient maintenance, wide range ratio, small pressure loss, low price, etc. Digital rotameter flow meter is widely used in chemical industry, petroleum, medicine, fertilizer, textile, synthetic fiber, food, sugar, dye, brewing, papermaking and other industries and laboratories. In addition to all the advantages of ordinary local reading rotameters, the digital rotameter flow meter has realized the remote transmission function, which can carry out long-distance measurement of toxic, harmful and dangerous places, output standard 4mA~20mA current signal, and can be connected to the computer to achieve automatic control.
When some rotameters and electric rotameters are used in combination with other instrumentation devices, they can also be used to measure the liquid level and density of the medium and perform composition analysis. The rotameter and electric remote rotameter can measure strong alkali, hydrofluoric acid, liquid, gas, steam and so on.
Compared with other principle flowmeters, the metal tube rotameter flowmeter has a simple structure and is suitable for high temperature and pressure flow measurement. This series of flowmeters include local indication VA flow meter, Digital rotameter flow meter, electric transmission type, rotameter for corrosive liquid or gas, explosion-proof rotameter, etc.
Digital rotameter flow meter working principle
In the vertical tapered metal tube, there is a magnetic float that can move up and down. When the fluid flows through the tapered metal tube from bottom to top, it is throttled by the magnetic float, and a differential pressure is generated between the upstream and downstream of the magnetic float to form a float Lifting force, when the lifting force on the float is greater than the gravity of the float in the fluid, the float will rise. As the float rises, the area of the annular gap between its maximum outer diameter and the tapered tube gradually increases, the fluid flow through the annular gap decreases, and the pressure difference between the upper and lower ends of the float decreases, so that the lifting force acting on the float gradually decreases. when the combined force of the lifting force and the gravity, buoyancy and resistance of the float is zero, the float is in a state of force balance, stable at a certain position, and is coupled with the magnetic steel of the indicator through the magnetic steel in the float. It is passed to the indicator, so that the pointer of the indicator rotates, indicating the size of the flow.
Fluids can be measured by Digital rotameter
Digital rotameter is used to measure below fluids : Water, solvent, diesel, kerosene, hydrochloric acid, sulfuric acid, hydrofluoric acid, steam, air, nitrogen, xylene, methanol, alcohol, naphtha, acetic acid, hydrogen peroxide, edible oil, palm oil, etc.;
Specifications of Digital rotameter flow meter
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(1) Nominal diameter of digital metal tube rotameter: DN 15 dial size, DN 20, DN 25, DN 25, DN 40, DN 50, DN 65, DN 80, DN 100, DNI 25, DNI 50, DN 200, DN 250;3/4”,1”,2”,3 inch, 4inch,6 inch, 8 “,10inch.,etc
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(2)Pressure rating: 1.0MPa, 1.6MPa, 2.5MPa, 4.0MPa, 6.3MPa, I0MPa, 150LB, 300LB, 600LB;
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(3) Accuracy class: 1.5
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(4) Turndown ratio: greater than 5:1, generally 10:1
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(5) Medium temperature: -80℃~400℃.
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(6) Power supply: AC power supply: 220V, 50Hz; DC power supply: 3.6V, I2V, 24V, 36V.
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(7) Load resistance: 350 Ω
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(8) Explosion-proof level: EX(ib)ⅡcT5
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(9) Output signal: 0~10mA, 4~20mA, 1V~5V(DC), 1V~I0V(DC), etc, option with relay outputs;
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(10) Ambient temperature: -25℃~55℃.
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(11) Connection form: flange connection, threaded connection, sanitary tri-clamp rotameter, etc.
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(12) Installation dimension of the flow meter: 250mm (10 inch) between flange and flange surface
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(13) Measuring range: water 1.5L/h~150000L/h; air: 0.05-4000 m3/h.
How to use digital metal tube rotameter
(1) Selection of flowmeter
Since the metal tube rotameter adopts the reference error, its scale gap is small, and the graduation value is large. In order to ensure the accuracy of measurement, the common flow rate should be kept at 70% to 80% of the maximum flow rate.
(2) Pressure loss
The pressure loss of the digital rotameter is relatively large, and the pressure loss of the orifice shape is larger than that of the conical tube shape, which can reach several tens of kPa. The flowmeter should be selected according to the actual situation.
(3) Flow correction
The flowmeter is generally calibrated with water under constant temperature conditions when it leaves the factory. The actual working conditions are often inconsistent with the calibration time. Since the liquid can be considered incompressible under medium and low pressure conditions, only density correction is required.
(4) Verification of metal tube float flowmeter
The metal tube rotameter is calibrated according to JJG 257 "variable area Flowmeter"
Digital rotameter flow meter Price
The price of digital flowmeter is determined by many factors, such as material, flow meter sensor size, function,brand , installation direction, etc.;
The larger the size of the flowmeter, the more expensive the price. For example, the price of 8” digital ratameter is much more expensive than that of 1/2”. The price of 8 inch electronic rotormeter is as high as 2500 US dollars, but the price of 1/2” digital VA flow meter is only 700 US dollars;
The material also has a great influence on the price of the digital VA flowmeter. The 316L flow sensor material is much more expensive than the 304 stainless steel material. 1” 304 SUS wet parts material digital rotameter costs $720, while the 316L SUS wet parts material, 1” electronic digital rotameter costs $850; the PTFE material is used to measure various Corrosive and aggressive medium, the price is more expensive than stainless steel;
Digital Rotameters are generally installed vertically, but with the update and development of instrument technology, the electronic VA flow meter installed horizontally have also made mature progress, which can stably measure various media, suitable for horizontal pipeline installation, and the flow direction can be from left to right, Or from right to left; a horizontally mounted electronic rotameter is more expensive than a vertically mounted variable area flow meter, eg a 2" vertically mounted variable area flow meter is $950, while a vertically mounted rotameter is $1150.
The digital rotameter flow meter can output 4-20mA or pulse. Some customers require RS485 communication, and the RS485 function will increase by 100 US dollars. Some customers want HART protocol, and the hart communication function also costs $80 more.
dwyer rotameter flow meter,yokogawa rotameter,brooks rotameter is world famous rotameter with high price, while a lot Chinese roatmeter manufactures also produce very reliable digital variable area flow meter with perfect and stable working, and the price is low.
