适用于小口径和低流速介质流量测量； ★ Metal tube float flowmeter is suitable for small diameter and low flow medium flow measurement;
★ Double-line large LCD display, optional on-site instantaneous / cumulative flow display, and single-axis sensitive indication with backlight;
★ Non-contact magnetic coupling transmission;
★ Metal tube float flow meter with all metal structure, suitable for high temperature, high pressure and strong corrosive media;
★ Can be used in flammable and explosive dangerous places;
★ Optional two-wire system, battery, AC power supply mode; multi-parameter calibration function;
★ Reliable work, small maintenance and long life;
★ Metal tube float flowmeters do not have high requirements for straight pipe sections;
★ Wide flow ratio is 10: 1;
★ Metal tube float flow meter with data recovery, data backup and power failure protection functions.
1 Application Overview
Float flowmeters are intuitive flow indicators or field indicators with low measurement accuracy requirements, accounting for more than 90% of the application of float flowmeters, and are widely used in power industry, petrochemical, chemical, metallurgical, pharmaceutical and other process industries and sewage treatment Utilities. Some application sites only need to monitor the flow rate not exceeding or not lower than a certain value. For example, the increase of the cable inert protective gas flow indicates that a new leak point has occurred.
The environmental protection atmospheric sampling and process industry online monitoring and analysis instruments continuously sample, and the sampling flow monitoring is also the bulk service object of the float flowmeter.
As the measurement of liquid level, density and other parameters in the process industry, constant flow measurement and control auxiliary instruments are widely used and also occupy a considerable share. Remote transmission metal float flow meters with signal output are commonly used in process industries for flow control detection instruments or pipeline mixing ratios, such as controlling the ratio of raw water and chemical solution in the water treatment process.
2 Type and structure selection
The main measurement object of the float flow meter is single-phase liquid or gas. Particles in the liquid or droplets in the gas are usually not applicable. Because the float adheres to particles or tiny bubbles in the liquid flow, it will affect the measured value.
If you need to transmit the signal far away for total accumulation or flow control, generally use a metal tube float flowmeter with electrical signal output. If the ambient atmosphere has explosion-proof requirements and there is a gas source for control instruments on the site, remote transmission metal float flow meters are given priority. If electric remote transmission instruments are selected, they must be explosion-proof.
较为普遍。 When measuring opaque liquids, a metal tube float meter is more common.
For measuring high-viscosity liquids with a temperature higher than the ambient temperature and liquids that easily precipitate crystals or solidify when the temperature drops, a jacketed metal tube float flow meter should be used.
Notes on installation and use
1 Instrument installation direction
Most of the float flowmeters must be installed vertically on vibration-free pipes, and there should be no obvious tilt, and the fluid flows through the meter from bottom to top. The angle between the center line and the plumb line of the float flowmeter generally does not exceed 5 degrees. If θ = 12 °, there will be 1% additional error. There is no strict requirement for the length of the upstream straight pipe section, but there are also manufacturers that require (2-5) D length, which is actually not necessary.
2 Installation for dirty fluids
A filter should be installed upstream of the meter. When a magnetically coupled metal tube float flowmeter is used for fluids that may contain magnetic impurities, a magnetic filter should be installed in front of the meter. To keep the float and cone tube clean, especially for small-caliber instruments, the cleanliness of the float significantly affects the measured value.
3 Installation of pulsating flow
The pulsation of the flow itself, if there is a reciprocating pump or regulating valve upstream of the proposed instrument position, or there is a large load change downstream, etc., the measurement position should be changed or the pipeline system should be remedied and improved, such as installing a buffer tank; if the instrument itself oscillates If the gas pressure is too low during measurement, the upstream valve of the instrument is not fully open, and the regulating valve is not installed downstream of the instrument, etc., it should be improved by targeted measures, or a meter with a damping device should be selected instead.
4 Extended range installation
If the measurement requires a wide range of flow, when the range exceeds 10, you can put two floats of different shapes and weights in one meter, take a light float reading when the flow is small, and take a heavy float reading after the float reaches the top. Can be expanded to 50-100.
5 To exhaust the gas in the instrument for liquid
Angle type metal float meter with inlet and outlet not in a straight line. When using liquid, pay attention to whether there is air remaining in the extended sleeve of the externally transmitted float. It must be drained out. If the liquid contains tiny bubbles, it will easily accumulate in the sleeve, and it should be drained regularly gas. This point is more important for small-caliber instruments, otherwise it will significantly affect the flow indication.
6 The flow value should be converted as necessary
If the instrument is not customized according to the medium parameters such as the density and viscosity, the meter for liquid is usually calibrated with water, and the gas meter is calibrated with air. The setting value is in the engineering standard state. When the fluid density, gas pressure and temperature of the operating conditions are inconsistent with the calibration, necessary conversion must be done. Conversion formulas and methods are detailed in each manufacturer's instruction manual.
7 Calibration and Calibration of Float Flowmeter
For float flowmeter calibration and calibration liquids are commonly used standard meter method, volume method and weighing method; gas is commonly used bell jar method, small flow using soap film method. The bulk products of some foreign manufacturers have achieved dry calibration, that is, controlling the size of the conical tube and the weight of the float, and indirectly determining the flow value to reduce costs. Only high-precision instruments are calibrated by solid flow. There are also some domestic manufacturers that strictly control the inner diameter and taper of the starting point of the conical tube and the size of the float. The actual flow verification only serves to check the quality of the inner surface of the conical tube. Gauges, tapered tubes and floats from these manufacturers have been interchanged and do not need to be replaced in sets. 采用标准表法校验是一种高效率方法。 It is a high-efficiency method to verify the standard method of metal float meter .
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