Vortex flowmeter working principle
The working principle of the vortex flowmeter is to arrange a vortex generator in the fluid, so that the vortex is alternately generated on both sides of the body, and the vortex column is asymmetrically arranged downstream of the vortex generator to generate a certain frequency, by the formula f= St*v/(1-1.27d/D)*d, (St is the Strauhal number, which is a dimensionless number, related to the vortex generator and Reynolds number; v is the flow velocity; d is the incident head width; D is the nominal diameter) to get the flow rate.
In general, the vortex flowmeter output signal (frequency) is not affected by changes in fluid properties and composition, which means that the meter factor is only related to the shape and size of the vortex generator and the Reynolds number. Its advantages are: simple and firm structure, convenient installation and maintenance; suitable for a variety of fluids, liquid, gas, steam and some mixed phases are applicable; high precision, generally up to ± 1% R; flow range is wide, up to 10 : 1 or 20:1 or more; low head loss; no zero drift; relatively cheap price; disadvantage: not suitable for low Reynolds number Re <20000, limited use of high viscosity, low flow rate, small diameter The requirements for the environment are high, and places with vibration should be eliminated as much as possible, and the upstream side needs to have a long straight pipe section; the meter factor is lower, and the larger the diameter, the lower the diameter. The signal resolution is reduced, so the aperture should not be too large, generally used in DN15~DN300mm.
The main technical parameters of ultrasonic external clamp flowmeter:
Measurement accuracy: better than 1%
Repeatability: better than 0.2%
Measurement period: 500ms (2 times per second, 128 sets of data collected per cycle)
Working power: 220VAC/8~36VDC
Maximum flow rate: 64m / s (flow rate resolution 0.001m / s)
Display: 2 × 10 Chinese characters backlit LCD can display instantaneous flow and positive, negative, net cumulative flow, flow rate, etc.
Operation: 4×4 touch keyboard (F4 main unit magnetic 4 button) operation
Signal input: 3 channels of 4-20mA analog input, accuracy 0.1%, can input pressure, liquid level, temperature and other signals
2-way three-wire PT100 platinum resistor
Signal output: 1 isolated RS485 output
1 way 4-20mA or 0-20mA output
1 channel isolated OCT (programmable between pulse width 6~1000ms, default 200ms)
1 relay output (pulse width 200ms)
Data storage: Optional built-in data storage (SD card) can store time, instantaneous flow, accumulated flow, signal status, etc., through special software, can import data into computer for statistical and management
Communication protocol: MODBUS protocol, M-BUS protocol, FUJI extension protocol, and compatible with communication protocols of similar products of other domestic manufacturers
Other functions: automatic memory before 512 days, the first 128 months, the first 10 years of positive / negative / net cumulative flow
Automatically remember the first 30 times of power-on and power-off time and flow rate, and can realize automatic or manual addition of traffic, which can be read by MODBUS protocol.
Programmable batch (quantitative) controller, fault self-diagnosis function
Software upgrade via code file transmitted via E-mail
Protection level: sensor IP68, F4 host IP68, remaining host IP65
Explosion-proof grade: EXdIIBT4 (JN-100F2 type)
Battery powered electromagnetic flowmeter features
1. Micro power consumption design, five 3.6V lithium batteries, continuous operation for 5~10 years, and easy to replace the battery.
2. The display adopts LCD large-screen liquid crystal display, which can display multiple flow parameters such as instantaneous flow rate, flow rate (pipe pressure), cumulative total amount of forward and reverse, and alarm prompt.
3. There are no movable and resistance parts in the measuring tube, no entanglement or clogging phenomenon, almost no pressure loss, and long-term reliable and continuous work.
4. Wide measurement range: The flow rate measurement range can reach 0.05m/s~10m/s.
5. High measurement accuracy: ±0.5% ~ ±1.0%.
6. Measurement stability: The measurement accuracy is not affected by changes in physical parameters such as temperature, pressure, viscosity and density of the measured medium.
7, with pulse output and GSM wireless data remote transmission.
8, with data storage function, up to 1000 groups of traffic data can be saved, and the data storage time can be arbitrarily set and data query.