的特点，在液体涡轮流量计的安装使用上还必须加以充分注意。 In order to give full play to the characteristics of the liquid turbine flowmeter, full attention must be paid to the installation and use of the liquid turbine flowmeter.
The liquid measured by the liquid turbine flowmeter is generally a low-viscosity (usually less than 15 × l0 -6 m 2 / s) and low-corrosive liquid. Although there are turbine flowmeters for measuring various media,
The measurement of high-viscosity and highly corrosive media still needs to be carefully considered and corresponding measures taken. When the medium viscosity v is greater than 15 × l0-6 m 2 / s, the meter coefficient of the flowmeter must be calibrated in real liquid, otherwise a larger error will occur.
Vapor-liquid two-phase flow, gas-solid two-phase flow, and dense-solid two-phase flow cannot be measured with turbine flow meters.
2. Installation piping requirements
The installation piping of the liquid turbine flowmeter has a great influence on the measurement accuracy of the flowmeter.
(1) Uneven velocity distribution and the existence of secondary flow in the tube are important factors affecting the accuracy of liquid turbine flowmeters. Therefore, the liquid turbine flowmeter has certain requirements for the upstream and downstream straight pipe sections. For industrial measurements,
Generally require straight pipe length of 20D upstream and 5D downstream. To eliminate pulsating flow, it is best to install a rectifier at the upstream end. If the upstream end can guarantee a straight pipe section of about 20D, and a rectifier is installed, the liquid turbine flowmeter can be measured.
Accuracy reaches the accuracy level of calibration.
对流体的清洁度有较高要求，在流量计前须安装过滤器来保证流体的清洁。 (2) Liquid turbine flowmeters have higher requirements for fluid cleanliness. Filters must be installed in front of the flowmeter to ensure the cleanliness of the fluid. The filter can be Y-shaped, its own cleanliness, and the differential pressure change at both ends can be measured
(3) To ensure that the liquid passing through the liquid turbine flowmeter is single-phase, that is, air or vapor cannot be allowed to enter the flowmeter, a deaerator should be installed upstream of the flowmeter if necessary. For easily vaporizable liquids, it must be ensured downstream of the flow meter
Be sure to back pressure. The magnitude of the back pressure may be double the pressure drop of the flow sensor at the maximum flow rate and 1.2 times the vapor pressure of the liquid at the maximum temperature.
3.Signal transmission line
In order to ensure that the display instrument has sufficient sensitivity to the pulse signal output by the turbine flowmeter sensor, it is necessary to improve the signal-to-noise ratio. For this reason, various electrical interference phenomena should be prevented during installation, namely electromagnetic induction, electrostatic and capacitive coupling.
Therefore, you must pay attention to the following points when configuring the signal transmission line:
(1) Limit the maximum length of the signal line. The maximum length of the signal line is L = dV; where V is the effective value of the output voltage of the sensing coil at the minimum flow rate, mV; d is the coefficient, m / mV, and its value Desirable: When V <1000mV,
d = 1.0; d = 2.0 at 1000mV and 5000mV.
(2) Shielded cables should be used for signal transmission lines to prevent induced noise from the outside. The transmission cable is required to be shielded and grounded at the display instrument end. The transmission cable should not be near strong electromagnetic equipment, and it should not be arranged near the power line.
Overview of Liquid Turbine Flowmeters
LWGY series turbine flowmeter is a new generation of turbine flowmeter that has been optimized by absorbing advanced technology from domestic and foreign flow meters. It has simple structure, light weight, high accuracy, good reproducibility, sensitive response, and convenient installation and maintenance.
Gauges are widely used to measure liquids that are not corroded with stainless steel 1Cr18Ni9Ti, 2Cr13, corundum Al2O3, and cemented carbide in closed pipelines, and have no impurities such as fibers and particles. They have a kinematic viscosity of less than 5 × 10-6m2 / s at operating temperature
For liquids with a kinematic viscosity greater than 5 × 10-6m2 / s, the flowmeter can be used for liquid calibration. If it is matched with a display instrument with special functions, it can also perform quantitative control, over-alarm, etc., which is ideal for flow measurement and energy saving.
This product contains pulse output, current signal output, internal lithium battery power supply and other forms to meet the various needs of users. The instrument is low in price, high in integration, and small in size. The product is also suitable for use with secondary display instruments, PLC,
DCS and other computer control systems are used together.
产品特点 Product Features of Liquid Turbine Flowmeter
1. High accuracy, generally up to ± 1% R, ± 0.5% R, high precision type can reach ± 0.2% R;
2. Good repeatability, short-term repeatability can reach 0.05% ~ 0.2%, it is precisely because of good repeatability, such as regular calibration or online calibration can get very high accuracy, is the preferred flowmeter in trade settlement ;
3. Output pulse frequency signal and 4-20MA current signal, suitable for total measurement and connection with computer, no zero drift, strong anti-interference ability;
4. Can get very high frequency signal (3-4kHz), strong signal resolution;
5. Wide range, medium and large caliber can reach 1:20, small caliber can be 1:10;
6. Compact and lightweight structure, convenient installation and maintenance, large circulation capacity;
7. Applicable for high-pressure measurement, there is no need to make holes in the meter body, and it is easy to make high-pressure meters;
8. There are many types of special-purpose sensors, which can be designed into various types of special-purpose sensors according to the special needs of users, such as low-temperature type, two-way type, downhole type, and sand mixing type;
9. Can be made into a plug-in type, suitable for large-caliber measurement, small pressure loss, low price, can be continuously removed, convenient installation and maintenance.