The choice of electromagnetic flowmeter is mainly the correct choice of the transmitter, and the converter only needs to be matched with it.
Choice of caliber and range
The diameter of the transmitter is usually the same as that of the piping system. If the piping system is to be designed, the diameter can be selected according to the flow range and flow rate. For electromagnetic flowmeters, the flow rate is suitable for 2 - 4m / s. In special cases, such as solid particles in the liquid, in consideration of wear, the optional flow rate is ≤ 3m / s, for easy to manage the fluid. Available flow rate ≥ 2m / s. After the flow rate is determined, the transmitter diameter can be determined according to qv= D2.
The range of the transmitter can be selected according to two principles: one is that the full scale of the meter is greater than the expected maximum flow value; the other is that the normal flow is greater than 50% of the full scale of the meter to ensure a certain measurement accuracy.
Temperature and pressure selection
There are certain restrictions on the fluid pressure and temperature that the electromagnetic flowmeter can measure. When used, the pressure used must be lower than the working pressure specified by the flowmeter. At present, the working pressure specifications of domestically produced electromagnetic flowmeters are:
Less than 50mm caliber, working pressure is 1.6MPa; 900 mm caliber, working pressure is 1 MPa;More than 1000mm caliber, working pressure is 0.6MPa.
If there are special requirements on the pressure resistance of the transmitter, you can negotiate with the manufacturer.
The operating temperature of the electromagnetic flowmeter depends on the lining material used, which is generally 5 - 70 ° C. Such as special treatment, can exceed the above range, such as the wear-resistant corrosion-resistant electromagnetic flowmeter produced by Tianjin Automation Instrument No.3. The transmitter allows the measured medium temperature to be -40 to 130 °C.
Selection of lining material and electrode tree material
The lining material and electrode material of the transmitter must be correctly selected according to the physical and chemical properties of the medium. Otherwise, the instrument will be damaged quickly due to the corrosion of the lining and the electrode, and the corrosive medium will easily cause an accident if it leaks. Therefore, the electrode and the lining material must be carefully selected according to the specific measurement medium in the production process.
Advantages of turbine flow meters
The pressure loss is small, and the impeller has anti-corrosion function;
1.Adopt advanced ultra-low power single-chip microcomputer technology, the whole machine has strong functions, low power consumption and superior performance.
2.Intelligent flow display with nonlinear accuracy compensation. Correction formula accuracy is better than ±0.02%
3.The meter factor can be set online by button and can be displayed on the LCD screen. The LCD screen is intuitive and clear, and the reliability is strong.
4.EEPROM is used to accumulate the flow and the meter coefficient is powered down. The protection time is more than 10 years.
5.Using high-performance MCU central processing unit to complete data acquisition and processing display output, cumulative flow instantaneous flow
6.The screen displays a convenient man-machine interface for data transfer in standard 485 format.
7.Fully hard alloy (tungsten carbide) shielded cantilever beam structure bearing, integrating rotary bearing and pressure bearing, greatly improving bearing life and working in medium with a small amount of sediment and dirt.
8.It adopts 1Cr18Ni9Ti all stainless steel structure (the turbine adopts 2Cr13) and has good anti-corrosion performance.
9.Easy to maintain, self-rectifying structure, small and light, simple structure, which can be combined in a short time.
10.Internal cleaning is simple.
11.Strong anti-magnetic interference and vibration capability, reliable performance and long life
12.The lower limit flow rate is low and the measuring range is wide.
13.The on-site display type LCD screen is clear and intuitive, with low power consumption. The 3V lithium battery can be operated continuously for more than 5 years.
Corrosion resistant, suitable for acid and alkali solutions
Executive Standard: JB/T 9248-1999
Nominal diameter: 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800, 3000
Maximum flow rate: 15m/s
Accuracy: DNl5~DN600, indication: ±0.3% (flow rate ≥1m/s); ±3mm/s (flow rate <1m/s)
DN700-DN3000, ±0.5% of the indicated value (flow rate ≥0.8m/S); ±4mm/s (flow rate <0.8m/S)
Fluid conductivity ≥5uS/cm
Nominal pressure:
DNl5～DN: 1504.0MPa, DNl5～DN600: 1.6MPa, DN200～DN1000: 1.0MPa, DN700～DN3000: 0.6MPa, Special order: 6.3, 10MPa
Ambient temperature
Sensor: -25 °C - ten 60 °C
Converter and integrated type: -10 ° C - ten 60 °C
Lining material: PTFE, neoprene, polyurethane, polytetrafluoroethylene (F46), screened PFA
Maximum fluid temperature
- Body type 70 °C
Separate type: Polychloroprene lining 80 ° C; 120 °C (specify when ordering)
Polyurethane lining 80 °C
PTFE lining
Polytetrafluoroethylene propylene (F46) 100 °C; 150 °C (specify when ordering)
Screening PFA
Signal electrode and grounding electrode material: stainless steel 0Crl8Nil2M02Ti, Hastelloy C, Hastelloy B, titanium, tantalum, platinum/rhodium alloy, stainless steel coated tungsten carbide
Electrode scraper mechanism: DN300-DN3000
Connecting flange material: carbon steel
Grounding flange material: stainless steel 1Crl8Ni9Ti
Import protection:
DN65—DNl50: Stainless steel 1Crl8Ni9Ti
Flange material
DN200～DNl600: Carbon steel ten stainless steel 1Crl8Ni9Ti
Shell protection
DNl5～DN3000 separate rubber or polyurethane lining sensor: IP65 or IP68
Other sensors, body flow meters and split converters: IP65
Spacing (separate type): The converter distance sensor generally does not exceed 100m