Metal tube float flowmeter is mainly used for small and medium caliber flow measurement, can measure liquid, gas, steam, etc., and is widely used.
1, metal tube float flow meter working principle:
The flow is measured according to the height of the metal tube float in the conical tube, and the weight of the float is balanced by the pressure difference generated when the fluid passes through the gap between the float and the tube wall. The greater the flow rate, the higher the float is supported, making it have The larger ring gap area, ie, the area of ​​the ring gap changes with the flow rate, is generally referred to as an area method. It is mostly used for the measurement of medium and small flow, and it is equipped with a type of electric remote transmission or gas remote transmission.
2, metal tube float flowmeter classification:
(1) Classification according to the conical tube material: it can be divided into transparent material conical tube and metal conical tube.
1 Transparent Tapered Tube Metal Tube Floater Flowmeter: Transparent conical tube material includes glass tube, transparent engineering plastics such as polystyrene, polycarbonate and plexiglass. Among them, glass tubes are used most often, but they are easily broken; while engineering plastic tubes are not easily broken, and some are also resistant to corrosive media such as acids and alkalis.
The diameter of the transparent conical tube float flowmeter is 15~40mm. The flow rate index is directly engraved on the outer wall of the conical tube, or an indexing ruler is installed beside the conical tube. The conical tube has a smooth surface with a cone and a guiding rib (or plane). ) Two kinds. The float moves freely in the cone or moves under the direction of the ribs of the cone. Larger smooth surfaces are also guided by guide rods.
2 Metal conical tube floater flowmeter: metal tube conical tube floater flowmeter diameter 15 ~ 40mm, through magnetic coupling and other means, the float displacement is transferred to the casing outside the conversion part. Compared with the transparent conical tube float flow meter. Can be used for higher media temperatures and pressures, and is not easily broken.
In addition, there are several other structures of the transparent float flowmeter. For example, the transparent straight tube float flowmeter is a deformed structure of a transparent conical tube float flowmeter, and the flow detection element is composed of an orifice plate and a conical floating plug. Metal tube conical tube float meters have other types or variants. Among them, the direct indication type directly reads the float position through the transparent straight pipe and the floating plug; the horizontal mounting type can be installed in the horizontal pipe; the straight through direction of the straight type and the typical structure is different, and the direction of the flow does not need to be changed, and the vertical pipe can be directly connected and installed. Convenient; The floating orifice plate type replaces the rotor conical tube with a floating orifice plate, and changing the flow specification is more convenient as long as the floating tape with different taper is replaced.
(2) Classification by flowmeter function: It can be divided into on-site instructions, remote transmission of pneumatic signals, output of electric remote transmission signals, and alarms. Transparent tube float flow meters are all on-site instructions. Sometimes equipped with proximity switches, output upper and lower limit alarm signal. The conversion part of the remote signal output type instrument converts the float displacement into current or air pressure analog quantity signal output, which respectively becomes a gas remote transmission float flowmeter and an electric remote transmission float flowmeter .
(3) Classification according to the connection mode with the pipeline: it can be divided into hose connection, flange connection and thread connection. There are three connection methods for transparent pipe float flowmeters, in which the hose connection is commonly used in gauges with a diameter of 10mm or less and places where the working pressure is lower; the thread connection is often used for instruments with a diameter of 40mm or less, and the application range is not wide; the flange connection is used Instrumentation with caliber 15~100mm is the most common application. Metal tube float meters are usually flanged and individual models are threaded.
(4) According to the fluid classification: can be divided into liquid, gas, and steam. Most float meters use the same meter to measure both liquid and gas. Measurement steam can only be used specially designed metal tube float flow meter, or add additional components on the standard instrument, such as adding the liquid damping parts with fins, install the heat sink and other parts of the connection with the instruction conversion part.
(5) According to the purpose of use: can be divided into basic type, jacket insulation type, explosion-proof type, corrosion-resistant type, blow type. The basic type of application is the most extensive. Jacket insulation type is used when the temperature in the piping is significantly higher (or lower) than the ambient temperature. When used with explosive gas or dust, electric remote flowmeters are explosion-proof. At present, there are flameproof design structures and intrinsically safe explosion-proof design structures in China. Corrosion-resistant float flowmeter and medium contact structure and float are made of PTFE and other engineering plastics. Blow-type flow rate is small, the air is 20~3000L/h, the water is 0.3~100L/h, the precision requirement is not high. The blow-flow type float flowmeter is combined with a small-scale self-operated differential pressure regulator to allow the flow rate variation caused by the pressure fluctuation of the power source or the disturbance of the downstream parameter change and self-regulation to maintain a constant flow rate.
(6) According to the way the measured fluid passes: it can be divided into full-flow type and diversion type. Full flow type refers to the flow of all the measured fluid through the float meter. Shunt type refers to only part of the measured fluid flowing through the float and other flow detection parts. The split flowmeter is composed of a standard orifice plate installed in the main pipe and a smaller diameter float flowmeter. It is used for large flow with a diameter greater than 50mm. And as long as the local instruction place.
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